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Java Set contains()用法及代码示例


Java.util.Set.contains()方法用于检查Set中是否存在特定元素。因此,本质上,它用于检查Set是否包含任何特定元素。

用法:

boolean contains(Object element)

参数:参数element 是Set类型的。无论是否存在于集合中,这都是需要测试的元素。


返回值:如果元素存在于集合中,则该方法返回true,否则返回False。

以下示例程序旨在说明Java.util.Set.contains()方法:

// Java code to illustrate Set.contains() method 
import java.io.*; 
import java.util.*; 
  
public class HashSetDemo { 
    public static void main(String args[]) 
    { 
        // Creating an empty Set 
        Set<String> set = new HashSet<String>(); 
  
        // Using add() method to add elements into the Set 
        set.add("Welcome"); 
        set.add("To"); 
        set.add("Geeks"); 
        set.add("4"); 
        set.add("Geeks"); 
  
        // Displaying the Set 
        System.out.println("Set: " + set); 
  
        // Check for "Geeks" in the set 
        System.out.println("Does the Set contains 'Geeks'? "
                           + set.contains("Geeks")); 
  
        // Check for "4" in the set 
        System.out.println("Does the Set contains '4'? "
                           + set.contains("4")); 
  
        // Check if the Set contains "No" 
        System.out.println("Does the Set contains 'No'? "
                           + set.contains("No")); 
    } 
}
输出:
Set: [4, Geeks, Welcome, To]
Does the Set contains 'Geeks'? true
Does the Set contains '4'? true
Does the Set contains 'No'? false

参考: https://docs.oracle.com/javase/7/docs/api/java/util/Set.html#contains(java.lang.Object)



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注:本文由纯净天空筛选整理自gopaldave大神的英文原创作品 Set contains() method in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。