极客教程Java 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，则返回真，否则返回假。
语法
public boolean isEmpty()Java
参数： 该函数不接受任何参数。
返回值： 如果列表为空，该函数返回真，否则返回假。
下面的程序说明了上述函数。
程序1 :
// 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<Integer> ArrLis
= new CopyOnWriteArrayList<Integer>();
// 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");
}
}Java
输出。
CopyOnWriteArrayList: [32, 67, 98, 100]
List is not empty
List is emptyJava
程序2
// 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<String> ArrLis
= new CopyOnWriteArrayList<String>();
// 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");
}
}Java
输出。
CopyOnWriteArrayList: [gopal, gfg, jgec, sudo]
List is not empty
List is emptyJava
参考资料: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArrayList.html#isEmpty-