Java中的 CopyOnWriteArrayList isEmpty() 方法

CopyOnWriteArrayList的isEmpty(E e)方法检查列表是否为空。如果列表为空，则返回 true，否则返回 false。

句法：

public boolean isEmpty()

参数：该函数不接受任何参数。

返回值：如果列表为空，该函数返回true ，否则返回false。

下面的程序说明了上述函数：

方案一：

// Java Program to illustrate the 
// isEmpty() method in Java
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create object of CopyOnWriteArrayList
        CopyOnWriteArrayList ArrLis
            = new CopyOnWriteArrayList();
  
        // Add elements
        ArrLis.add(32);
        ArrLis.add(67);
        ArrLis.add(98);
        ArrLis.add(100);
  
        // print CopyOnWriteArrayList
        System.out.println("CopyOnWriteArrayList: " + ArrLis);
  
        // check using function
        if (ArrLis.isEmpty())
            System.out.println("List is empty");
        else
            System.out.println("List is not empty");
  
        ArrLis.clear();
  
        // check using function
        if (ArrLis.isEmpty())
            System.out.println("List is empty");
        else
            System.out.println("List is not empty");
    }
}

输出：

CopyOnWriteArrayList: [32, 67, 98, 100]
List is not empty
List is empty

方案二：

// Java Program to illustrate the 
// isEmpty() method in Java
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create object of CopyOnWriteArrayList
        CopyOnWriteArrayList ArrLis
            = new CopyOnWriteArrayList();
  
        // Add elements
        ArrLis.add("gopal");
        ArrLis.add("gfg");
        ArrLis.add("jgec");
        ArrLis.add("sudo");
  
        // print CopyOnWriteArrayList
        System.out.println("CopyOnWriteArrayList: " + ArrLis);
  
        // check using function
        if (ArrLis.isEmpty())
            System.out.println("List is empty");
        else
            System.out.println("List is not empty");
  
        ArrLis.clear();
  
        // check using function
        if (ArrLis.isEmpty())
            System.out.println("List is empty");
        else
            System.out.println("List is not empty");
    }
}

输出：

CopyOnWriteArrayList: [gopal, gfg, jgec, sudo]
List is not empty
List is empty

参考： https: Java/util/concurrent/CopyOnWriteArrayList.html#isEmpty–