IdentityHashMap类isEmpty()方法 (IdentityHashMap 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 IdentityHashMap is "empty" or "not empty".

  isEmpty()方法用于检查此IdentityHashMap是“空”还是“非空”。

• 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 IdentityHashMap.

  在检查此IdentityHashMap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 IdentityHashMap is "empty" or "non-empty".

该方法的返回类型为boolean ，如果此IdentityHashMap为“空”或“非空”，则返回true。

Example:

例：

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

Output

输出量

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

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