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Java WeakHashMap containsKey() Method with Example

WeakHashMap Class containsKey() method: Here, we are going to learn about the containsKey() method of WeakHashMap Class with its syntax and example.
Submitted by Preeti Jain, on February 23, 2020

WeakHashMap Class containsKey() method

• containsKey() method is available in java.util package.
• containsKey() method is used to check whether this map object contains a mapping 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 existence of the given object.

Syntax:

    public boolean containsKey(Object key_ele);

Parameter(s):

• Object key_ele – represents the key element (key_ele) whose existence is to be checked in this map.

Return value:

The return type of the method is boolean, it returns true when mapping exists 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 WeakHashMap 

import java.util.*;

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

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

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

        // By using containsKey() method is
        // to check whether this map associates
        // any value for the given key element
        // of this WeakHashMap
        boolean status = map.containsKey(30);

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

Output

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