Java IdentityHashMap remove() method

The remove(Object key) method of the Java IdentityHashMap class is used remove the linkage of the specified key, from the calling IdentityHashMap, if present.

Syntax

Parameters

key - Key whose linkage is to be removed.

Return

The previous value linked with the specified key, or null if there was no linkage.

Example 1

import java.util.IdentityHashMap;

public class IdentityHashMapRemoveExample1 {
     public static void main(String[] args) {
   //Creating an object of IdentityHashMap class
   IdentityHashMap<String,Integer> map1 = new IdentityHashMap<String,Integer>(6);
      
   //Putting key-value pairs inside map1
   map1.put("Java", 1);
   map1.put("is", 2);
   map1.put("the", 3);
   map1.put("best", 4);
   map1.put("programming", 5);
   map1.put("language", 6);
   
   //Displaying elements of map1
   System.out.println(map1);
   
   //Removing some linkage from the map
   System.out.println(map1.remove("the"));
   System.out.println(map1.remove("best"));
   
   //Displaying elements of map1 after removing some elements
   System.out.println(map1);
         
}
}

Output:

{Java=1, the=3, language=6, programming=5, best=4, is=2}
3
4
{Java=1, language=6, programming=5, is=2}

Example 2

import java.util.IdentityHashMap;

class Student{
    private int roll;
    private String name;
    private int standard;
    
    public Student(int roll,String name,int standard){
        this.roll = roll;
        this.name = name;
        this.standard = standard;
    }
    
    public String disp(){
        return roll+" "+name+" "+standard;
    }
}

public class IdentityHashMapRemoveExample2 {
    public static void main(String[] args) {
        
        //Creating Objects of Student class
        Student stud1 = new Student(1 ,"Ram ",10);
        Student stud2 = new Student(2 ,"Shyam ",10);
        Student stud3 = new Student(3 ,"Aman ",12);
        Student stud4 = new Student(4 ,"Harsh ",12);
        Student stud5 = new Student(5 ,"Shivam",11);
        
        //Creating an instance of IdentityHashMap
        IdentityHashMap<Integer,Student> map1 = new IdentityHashMap<Integer,Student>(5);
                
        //Inserting the Student class objects into IdentityHashMap
        map1.put(1,stud1);
        map1.put(2,stud2);
        map1.put(3,stud3);
        map1.put(4,stud4);
        
        //Displaying elements of map1
        System.out.println(map1);
        
        //Removing elements from map1
        System.out.println(map1.remove(2));
        System.out.println(map1.remove(3));
        
        //Displaying elements of map1 after removing some elements
        System.out.println(map1);
}
}

Output:

{[email protected], [email protected], [email protected], [email protected]}
[email protected]
[email protected]
{[email protected], [email protected]}

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