Java 中的 CopyOnWriteArrayList isEmpty()方法
原文:https://www . geeksforgeeks . org/copy onwriterarraylist-isempty-method-in-Java/
是 的空方法 检查列表是否为空。如果列表为空，则返回 true，否则返回 false。
语法:
public boolean isEmpty()
参数:函数不接受任何参数。
返回值:如果列表为空，则函数返回真，否则返回假。
以下程序说明了上述功能:
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");
}
}
输出:
CopyOnWriteArrayList: [32, 67, 98, 100]
List is not empty
List is empty
程序二:
// 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<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");
}
}
输出:
CopyOnWriteArrayList: [gopal, gfg, jgec, sudo]
List is not empty
List is empty
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