Java CopyOnWriteArraySet contains()用法及代碼示例

CopyOnWriteArraySet的contains(E e)方法檢查Set中是否存在給定元素。

用法:

public boolean contains(Object o)

參數：該函數接受單個強製參數，該參數指定要在Set中檢查其外觀的元素。

返回值：如果該元素存在，則該函數返回true，否則返回false。

以下示例程序旨在說明上述函數：

示例1:

// Java Program to illustrate the CopyOnWriteArraySet 
// contains() 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(67); 
        ArrSet.add(100); 
  
        // print CopyOnWriteArraySet 
        System.out.println("CopyOnWriteArraySet: "
                           + ArrSet); 
  
        // check if 100 is present 
        // using contains() function 
        if (ArrSet.contains(100)) 
            System.out.println("100 is "
                               + "present in the Set"); 
        else
            System.out.println("100 is "
                               + "not present in the Set"); 
  
        // check if 20 is present 
        // using contains() function 
        if (ArrSet.contains(20)) 
            System.out.println("20 is "
                               + "present in the Set"); 
        else
            System.out.println("20 is "
                               + "not present in the Set"); 
    } 
}

輸出：

CopyOnWriteArraySet: [32, 67, 100]
100 is present in the Set
20 is not present in the Set

示例2:

// Java Program to illustrate the CopyOnWriteArraySet 
// contains() 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>(); 
  
        // Add elements 
        ArrSet.add("geeks"); 
        ArrSet.add("gfg"); 
        ArrSet.add("jgec"); 
        ArrSet.add("sudo"); 
  
        // print CopyOnWriteArraySet 
        System.out.println("CopyOnWriteArraySet: "
                           + ArrSet); 
  
        // check using contains() function 
        if (ArrSet.contains("gfg")) 
            System.out.println("gfg is "
                               + "present in the Set"); 
        else
            System.out.println("gfg is "
                               + "not present in the Set"); 
  
        // check using contains() function 
        if (ArrSet.contains("best")) 
            System.out.println("best is "
                               + "present in the Set"); 
        else
            System.out.println("best is "
                               + "not present in the Set"); 
    } 
}

輸出：

CopyOnWriteArraySet: [geeks, gfg, jgec, sudo]
gfg is present in the Set
best is not present in the Set

參考： https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArraySet.html#contains-java.lang.Object-

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