Java中的HashSet contains() 方法

Java.util.HashSet.contains() 方法用于检查HashSet中是否存在特定元素。所以基本上它是用来检查Set是否包含任何特定元素。

语法:

HashSet.contains(Object element)

参数: 参数element是HashSet类型的。这是需要测试是否存在于Set中的元素。

返回值: 如果元素在集合中，则该方法返回true，否则返回False。

下面的程序说明了Java.util.HashSet.contains()方法：

// Java code to illustrate HashSet.contains() method
import java.io.*;
import java.util.HashSet;
  
public class HashSetDemo {
    public static void main(String args[])
    {
        // Creating an empty HashSet
        HashSet<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 HashSet
        System.out.println("HashSet: " + 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"));
    }
}

HashSet: [4, Geeks, Welcome, To]
Does the Set contains 'Geeks'? true
Does the Set contains '4'? true
Does the Set contains 'No'? false