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Java HashMap containsKey() Method with Example

HashMap Class containsKey() method: Here, we are going to learn about the containsKey() method of HashMap Class with its syntax and example.
Submitted by Preeti Jain, on March 04, 2020

HashMap Class containsKey() method

• containsKey() method is available in java.util package.
• containsKey() method is used to check whether this HashMap associates any value for the given key element (key_ele) or not.
• containsKey() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• containsKey() method does not throw an exception at the time of checking the given key element.

Syntax:

    public boolean containsKey(Object key_ele);

Parameter(s):

• Object key_ele – represents the key element to test the existence of its associated value.

Return value:

The return type of the method is boolean, it returns true when this HashMap hold at least one value element for the given key element (key_ele) otherwise it returns false.

Example:

// Java program to demonstrate the example 
// of boolean containsKey(Object key_ele)
// method of HashMap 

import java.util.*;

public class ContainsKeyOfHashMap {
    public static void main(String[] args) {
        // Instantiates a HashMap object
        Map < Integer, String > map = new HashMap < Integer, String > ();

        // By using put() method is to add
        // key-value pairs in a HashMap
        map.put(10, "C");
        map.put(20, "C++");
        map.put(50, "JAVA");
        map.put(40, "PHP");
        map.put(30, "SFDC");

        // Display HashMap
        System.out.println("HashMap: " + map);

        // By using containsKey() method is
        // to check whether this map associates
        // any value for the given key element or not
        // in this HashMap
        boolean status = map.containsKey(30);

        System.out.print("map.containsKey(30): ");
        System.out.println(status);
    }
}

Output

HashMap: {50=JAVA, 20=C++, 40=PHP, 10=C, 30=SFDC}
map.containsKey(30): true