类的继承和重写方法

以你之姓@ 2024-03-24 15:12 100阅读 0赞

**1** **问题**

子类中如何继承父类的方法，或者如何重写方法。

**2** **方法**

![561065b572a5a86e16cee42b558fb964.png][]首先得在父类中创建一个方法，利用创建的方法的格式void+方法名()\{\},然后在子类中调用这个方法：直接输入方法名，再按enter，便会出现super.方法名(),表示调用该方法。当不想调用父类的方法时可直接删除super的调用，然后在方法中重新写。

例题：4、 请设计2个类，分别是学生类Student，本科生类Undergraduate，，其中Student类是一个抽象类，它包含一些基本的学生信息，如姓名、类别（本科生还是研究生）、所学课程（这里假定为3门课，用一维数组表示）成绩和成绩等级等，而Undergraduate类是Student类的子类.

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 <td>package lab02; public class Student { &nbsp; &nbsp;//属性 &nbsp; &nbsp;String name; &nbsp; &nbsp;String type;//类别 &nbsp; &nbsp;int[] courseScores;//三门课的成绩数组 &nbsp; &nbsp;String grade;//平均成绩等级 &nbsp; &nbsp;Student(){} &nbsp; &nbsp;Student(String name,String type,int[] courseScores){ &nbsp; &nbsp; &nbsp; &nbsp;this.name=name; &nbsp; &nbsp; &nbsp; &nbsp;this.type=type; &nbsp; &nbsp; &nbsp; &nbsp;this.courseScores=courseScores; &nbsp; &nbsp;} &nbsp; &nbsp;void computeGrade(){ &nbsp; &nbsp; &nbsp; &nbsp;System.out.println("Student:compute"); } package lab02; public class Undergraduate extends Student{ &nbsp; &nbsp;Undergraduate(){} &nbsp; &nbsp;Undergraduate(String name,String type,int[] courseScores){ &nbsp; &nbsp; &nbsp; &nbsp;super(name,type,courseScores); &nbsp; &nbsp;} &nbsp; &nbsp;@Override//该方法来自于父类，然后不适合子类（是直接写函数名再enter回车直接得来的） &nbsp; &nbsp;void computeGrade() { // &nbsp; &nbsp; &nbsp; &nbsp;super.computeGrade();//super表示执行父类方法 &nbsp; &nbsp; &nbsp; &nbsp;System.out.println("Undergraduate:compute"); &nbsp; &nbsp; &nbsp; &nbsp;Int avg=(this.courseScores[0]+this.courseScores[1]+this.courseScores[2])/3; &nbsp; &nbsp; &nbsp; &nbsp;if(avg&gt;80){ &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;this.grade="优秀"; &nbsp; &nbsp; &nbsp; &nbsp;}else if(avg&gt;60){ &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;this.grade="良好"; &nbsp; &nbsp; &nbsp; &nbsp;}else if(avg&lt;60){ &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;this.grade="差"; &nbsp; &nbsp; &nbsp; &nbsp;} &nbsp; &nbsp;} } package lab02; public class Test04 { &nbsp; &nbsp;public static void main(String[] args) { &nbsp; &nbsp; &nbsp; &nbsp;Undergraduate zhang=new Undergraduate("张三","本科生",new int[]{90,95,100}); &nbsp; &nbsp; &nbsp; &nbsp;zhang.computeGrade(); &nbsp; &nbsp; &nbsp; &nbsp;System.out.println("等级："+zhang.grade);</td> 
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**3** **结语**

针对继承父类的方法和重写方法的问题，我们的重点是理解如何调用函数的，如何在子类中使用该方法，要使用的父类的方法名加enter即可，当不想执行父类方法去掉super,自己重写方法即可。

[561065b572a5a86e16cee42b558fb964.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/24/9ba3bd3742544544b4a2fd0e80c30680.png