Java ConcurrentHashMap keys() Method

The keys() method of ConcurrentHashMap class returns an enumeration of the keys in this table.

Syntax

Parameter

No parameter is passed.

Returns

an enumeration of the keys in this table

Throws

No exception is thrown.

Example 1

import java.util.*; 
import java.util.concurrent.*; 
  
public class ConcurrentHashMapKeysExample1 { 
    public static void main(String[] args) 
    { 
        ConcurrentHashMap<Integer, String>  conmap = new ConcurrentHashMap<Integer, String>(); 
        conmap.put(10, "Java"); 
        conmap.put(11, ".net"); 
        conmap.put(20, "php"); 
        conmap.put(12, "C"); 
        conmap.put(30, "C++"); 
        // print statement
        System.out.println(" Map : " + conmap); 
        Enumeration enumr = conmap.keys(); 
        System.out.println(" enumeration of keys are:"); 
        while (enumr.hasMoreElements()) { 
            System.out.println(enumr.nextElement()); 
        } 
    } 
}

Test it Now

Output:

enumeration of keys are:
20
10
11
12
30

Example 2

import java.util.*; 
import java.util.concurrent.*; 
  
public class ConcurrentHashMapKeysExample2 { 
    public static void main(String[] args) 
    { 
        ConcurrentHashMap<String , String>  conmap = new ConcurrentHashMap<String, String>(); 
        conmap.put("A", "Java"); 
        conmap.put("B", ".net"); 
        conmap.put("C", "php"); 
        conmap.put("D", "C"); 
        conmap.put("E", "C++"); 
       // print statement
        System.out.println(" Map : " + conmap); 
        Enumeration enumr = conmap.keys(); 
        System.out.println(" enumeration of keys are:"); 
        while (enumr.hasMoreElements()) { 
            System.out.println(enumr.nextElement()); 
        } 
    } 
}

Test it Now

Output: