CopyOnWriteArraySet的isEmpty(E e)方法检查Set是否为空。如果Set为空,则返回true,否则返回false。
用法:
public boolean isEmpty()
返回值:如果Set为空,则该函数返回true,否则返回false。
以下示例程序旨在说明上述函数:
示例1:
// Java Program to illustrate the
// isEmpty() method in Java
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// create object of CopyOnWriteArraySet
CopyOnWriteArraySet<Integer> ArrSet
= new CopyOnWriteArraySet<Integer>();
// Add elements
ArrSet.add(32);
ArrSet.add(67);
ArrSet.add(98);
ArrSet.add(100);
// print CopyOnWriteArraySet
System.out.println("CopyOnWriteArraySet: " + ArrSet);
// check using function
if (ArrSet.isEmpty())
System.out.println("\nSet is empty");
else
System.out.println("\nSet is not empty");
}
}
输出:
CopyOnWriteArraySet: [32, 67, 98, 100] Set is not empty
示例2:
// Java Program to illustrate the
// isEmpty() method in Java
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// create object of CopyOnWriteArraySet
CopyOnWriteArraySet<String> ArrSet
= new CopyOnWriteArraySet<String>();
// print CopyOnWriteArraySet
System.out.println("CopyOnWriteArraySet: "
+ ArrSet);
// check using function
if (ArrSet.isEmpty())
System.out.println("\nSet is empty");
else
System.out.println("\nSet is not empty");
}
}
输出:
CopyOnWriteArraySet: [] Set is empty
参考: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArraySet.html#isEmpty–
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