hashmap示例_Java HashMap isEmpty（）方法与示例

朱雀 2023-03-05 13:29 122阅读 0赞

hashmap示例

## HashMap类isEmpty()方法 **(**HashMap Class isEmpty() method**)** ##

*  **isEmpty() method** is available in java.util package.
    
    **isEmpty()方法**在java.util包中可用。
 *  **isEmpty() method** is used to check whether this HashMap is "empty" (i.e. No key-value pairs exist) or "not empty".
    
    **isEmpty()方法**用于检查此HashMap是“空”(即不存在键值对)还是“不为空”。
 *  **isEmpty() method** is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
    
    **isEmpty()方法**是一个非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。
 *  **isEmpty() method** does not throw an exception at the time of checking the empty status of this HashMap.
    
    在检查此HashMap的空白状态时， **isEmpty()方法**不会引发异常。

**Syntax:**

**句法：**

public boolean isEmpty();

**Parameter(s):**

**参数：**

*  It does not accept any parameter.
    
    它不接受任何参数。

**Return value:**

**返回值：**

The return type of the method is boolean, it returns true when this HashMap is empty otherwise it returns false.

方法的返回类型为boolean ，如果此HashMap为空，则返回true，否则返回false。

**Example:**

**例：**

// Java program to demonstrate the example 
    // of boolean isEmpty() method of HashMap 
    
    import java.util.*;
    
    public class IsEmptyOfHashMap {
        
        public static void main(String[] args) {
        
            // Instantiates a HashMap object
            Map < Integer, String > map = new HashMap < Integer, String > ();
    
            // By using put() method is to add
            // key-value pairs in a HashMap
            map.put(10, "C");
            map.put(20, "C++");
            map.put(50, "JAVA");
            map.put(40, "PHP");
            map.put(30, "SFDC");
    
            // Display HashMap
            System.out.println("HashMap: " + map);
    
            // By using isEmpty() method is to
            // check whether this HashMap is
            // empty or not
            boolean status = map.isEmpty();
    
            // Display status
            System.out.print("map.isEmpty(): ");
            System.out.println(status);
        }
    }

**Output**

**输出量**

HashMap: {50=JAVA, 20=C++, 40=PHP, 10=C, 30=SFDC}
    map.isEmpty(): false

> 翻译自: [https://www.includehelp.com/java/hashmap-isempty-method-with-example.aspx][https_www.includehelp.com_java_hashmap-isempty-method-with-example.aspx]

hashmap示例

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