Java中浅拷贝与深拷贝之间的区别

àì夳堔傛蜴生んèń 2023-10-05 19:24 82阅读 0赞

在深入探讨Java中浅表副本与深表副本之间的差异之前，让我们看看首先进行克隆的是什么。

### 什么是克隆？ ###

**克隆**是在内存中创建现有对象的精确副本的过程。在Java中，**java.lang.Object**类的**clone（）**方法用于克隆过程。此方法创建一个对象的精确副本，并**通过逐字段分配**在其上对其进行调用，并返回该对象的引用。并非Java中的所有对象都适用于克隆过程。实现**Cloneable接口**的对象仅适用于克隆过程。可克隆接口是 [标记器接口][Link 1]，用于为克隆过程提供标记。单击[此处][Link 2]以查看有关Java中clone（）方法的更多信息。

浅拷贝和深拷贝都与此克隆过程有关。默认版本的clone（）方法创建对象的浅表副本。要创建对象的深层副本，您必须重写clone（）方法。让我们看看这些浅拷贝和深拷贝是如何工作的。

### Java中的浅表复制： ###

默认版本的clone（）方法创建对象的浅表副本。对象的浅表副本将具有原始对象所有字段的精确副本。如果原始对象具有对其他对象的任何引用作为字段，则仅将那些对象的引用复制到克隆对象中，而不创建这些对象的副本。这意味着通过克隆对象对这些对象所做的任何更改都将反映在原始对象中，反之亦然。浅拷贝并非与原始对象100％脱离。浅拷贝不是100％独立于原始对象。

下面是创建对象“ **student1** ”的浅表副本的**示例**。

<table> 
 <tbody> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;"> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">1个</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">2</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">3</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">4</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">5</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">6</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">7</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">8</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">9</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">10</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">11</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">12</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">13</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">14</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">15</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">16</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">17</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">18岁</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">19</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">20</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">21</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">22</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">23</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">24</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">25</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">26</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">27</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">28</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">29</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">30</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">31</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">32</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">33</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">34</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">35</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">36</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">37</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">38</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">39</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">40</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">41</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">42</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">43</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">44</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">45</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">46</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">47</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">48</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">49</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">50</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">51</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">52</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">53</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">54</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">55</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">56</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">57</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">58</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">59</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">60</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">61</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">62</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">63</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">64</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">65岁</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">66</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">67</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">68</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">69</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">70</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">71</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">72</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">73</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">74</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">75</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">76</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">77</span></span> 
    </div> </td> 
   <td style="text-align:left;vertical-align:baseline;"> 
    <div style="margin-left:0px;"> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>class</code> <code>Course</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String subject1;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String subject2;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String subject3;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code> <code>Course(String sub1, String sub2, String sub3)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.subject1 = sub1;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.subject2 = sub2;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.subject3 = sub3;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>class</code> <code>Student </code><code>implements</code> <code>Cloneable</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>int</code> <code>id;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String name;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Course course;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code> <code>Student(</code><code>int</code> <code>id, String name, Course course)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.id = id;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.name = name;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.course = course;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>//Default version of clone() method. It creates shallow copy of an object.</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>protected</code> <code>Object clone() </code><code>throws</code> <code>CloneNotSupportedException</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>return</code> <code>super</code><code>.clone();</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>public</code> <code>class</code> <code>ShallowCopyInJava</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code> <code>static</code> <code>void</code> <code>main(String[] args)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Course science = </code><code>new</code> <code>Course(</code><code>"Physics"</code><code>, </code><code>"Chemistry"</code><code>, </code><code>"Biology"</code><code>);</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Student student1 = </code><code>new</code> <code>Student(</code><code>111</code><code>, </code><code>"John"</code><code>, science);</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Student student2 = </code><code>null</code><code>;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>try</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>//Creating a clone of student1 and assigning it to student2</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>student2 = (Student) student1.clone();</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>catch</code> <code>(CloneNotSupportedException e)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>e.printStackTrace();</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>//Printing the subject3 of 'student1'</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(student1.course.subject3);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </code><code>//Output : Biology</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>//Changing the subject3 of 'student2'</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>student2.course.subject3 = </code><code>"Maths"</code><code>;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>//This change will be reflected in original student 'student1'</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(student1.course.subject3);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </code><code>//Output : Maths</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>}</code></span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

在上面的示例中，“ **student1** ”是“ **Student** ”类的对象，它具有三个字段**-id**，**name**和**course**。“**课程**”是指向“**课程**”类型对象的参考变量。“ **student1** ”的克隆是通过调用克隆方法创建的，并将其分配给“ **student2** ”。当克隆方法的默认版本创建浅表副本时，“ **student1** ”和“ **student2** ”的“**课程**”字段将指向相同的“**课程**”对象。因此，通过' **student2**对该对象进行的任何更改将会反映在“ **student1** ”中，反之亦然。

请参阅下面的图片以获得更清晰的了解。

![Java中的浅表复制与深表复制][Java]

### Java深拷贝： ###

对象的深层副本将具有原始对象所有字段的精确副本，就像浅层副本一样。但另外，如果原始对象具有对其他对象的任何引用作为字段，则还可以通过在它们上调用clone（）方法来创建这些对象的副本。这意味着克隆对象和原始对象将是100％不相交的。他们将彼此100％独立。对克隆对象所做的任何更改都不会反映在原始对象中，反之亦然。

要创建对象的深层副本，您必须重写clone（）方法，如以下示例所示。

<table> 
 <tbody> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;"> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">1个</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">2</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">3</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">4</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">5</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">6</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">7</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">8</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">9</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">10</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">11</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">12</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">13</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">14</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">15</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">16</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">17</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">18岁</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">19</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">20</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">21</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">22</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">23</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">24</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">25</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">26</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">27</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">28</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">29</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">30</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">31</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">32</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">33</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">34</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">35</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">36</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">37</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">38</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">39</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">40</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">41</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">42</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">43</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">44</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">45</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">46</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">47</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">48</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">49</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">50</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">51</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">52</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">53</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">54</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">55</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">56</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">57</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">58</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">59</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">60</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">61</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">62</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">63</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">64</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">65岁</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">66</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">67</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">68</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">69</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">70</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">71</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">72</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">73</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">74</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">75</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">76</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">77</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">78</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">79</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">80</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">81</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">82</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">83</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">84</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">85</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#000000;"><span style="color:#afafaf;">86</span></span> 
    </div> </td> 
   <td style="text-align:left;vertical-align:baseline;"> 
    <div style="margin-left:0px;"> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>class</code> <code>Course </code><code>implements</code> <code>Cloneable</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String subject1;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String subject2;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String subject3;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code> <code>Course(String sub1, String sub2, String sub3)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.subject1 = sub1;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.subject2 = sub2;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.subject3 = sub3;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>protected</code> <code>Object clone() </code><code>throws</code> <code>CloneNotSupportedException</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>return</code> <code>super</code><code>.clone();</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>class</code> <code>Student </code><code>implements</code> <code>Cloneable</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>int</code> <code>id;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>String name;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Course course;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code> <code>Student(</code><code>int</code> <code>id, String name, Course course)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.id = id;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.name = name;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>this</code><code>.course = course;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>//Overriding clone() method to create a deep copy of an object.</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>protected</code> <code>Object clone() </code><code>throws</code> <code>CloneNotSupportedException</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Student student = (Student) </code><code>super</code><code>.clone();</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>student.course = (Course) course.clone();</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>return</code> <code>student;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>public</code> <code>class</code> <code>DeepCopyInJava</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>public</code> <code>static</code> <code>void</code> <code>main(String[] args)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Course science = </code><code>new</code> <code>Course(</code><code>"Physics"</code><code>, </code><code>"Chemistry"</code><code>, </code><code>"Biology"</code><code>);</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Student student1 = </code><code>new</code> <code>Student(</code><code>111</code><code>, </code><code>"John"</code><code>, science);</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>Student student2 = </code><code>null</code><code>;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>try</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>//Creating a clone of student1 and assigning it to student2</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>student2 = (Student) student1.clone();</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>catch</code> <code>(CloneNotSupportedException e)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>{ </code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>e.printStackTrace();</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>//Printing the subject3 of 'student1'</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(student1.course.subject3);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </code><code>//Output : Biology</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>//Changing the subject3 of 'student2'</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>student2.course.subject3 = </code><code>"Maths"</code><code>;</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>//This change will not be reflected in original student 'student1'</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;">&nbsp;</span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>System.out.println(student1.course.subject3);&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </code><code>//Output : Biology</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#000000;"><code>}</code></span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

下图显示了如何创建“ student1”的深层副本。

![Java中的浅表复制与深表复制][Java 1]

### 浅拷贝与深拷贝在Java中： ###

以下是Java中浅表复制和深表复制之间的差异列表。

<table> 
 <tbody> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;"><strong>浅拷贝</strong></span></td> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;"><strong>深拷贝</strong></span></td> 
  </tr> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;">克隆对象和原始对象不是100％不相交的。</span></td> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;">克隆对象和原始对象是100％不相交的。</span></td> 
  </tr> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;">对克隆对象所做的任何更改都将反映在原始对象中，反之亦然。</span></td> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;">对克隆对象所做的任何更改都不会反映在原始对象中，反之亦然。</span></td> 
  </tr> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;">默认版本的clone方法创建对象的浅表副本。</span></td> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;">要创建对象的深层副本，您必须重写clone方法。</span></td> 
  </tr> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;">如果对象只有原始字段，则首选浅复制。</span></td> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;">如果对象具有对其他对象的引用作为字段，则首选深度复制。</span></td> 
  </tr> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;">浅拷贝速度快，而且价格便宜。</span></td> 
   <td style="text-align:left;vertical-align:baseline;"><span style="color:#000000;">深拷贝很慢，而且非常昂贵。</span></td> 
  </tr> 
 </tbody> 
</table>

[Link 1]: https://javaconceptoftheday.com/marker-interface-java/
[Link 2]: https://javaconceptoftheday.com/clone-method-java-lang-object-class/
[Java]: https://img-blog.csdnimg.cn/img_convert/e18099a936891e09b7ccfe0cc3c77c5e.png
[Java 1]: https://img-blog.csdnimg.cn/img_convert/6aa9ce26a77bb484edd3ccf299f7bce9.png