Java IdentityHashMap get() Method

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Description

The Java IdentityHashMap get(Object key) method is used to get the value to which the specified key is mapped in this identity hash map, or null if the map contains no mapping for this key.

Declaration

Following is the declaration for java.util.IdentityHashMap.get() method.

public V get(Object key)

Parameters

key − This is the key whose associated value is to be returned.

Return Value

The method call returns 'true' if the value to which this map maps the specified key, or null if the map contains no mapping for this key.

Exception

NA

Getting a Value from an IdentityHashMap of Integer, Integer Pair Example

The following example shows the usage of Java IdentityHashMap get() method to get a value based on a key from a Map. We've created a Map object of Integer,Integer pairs. Then few entries are added, map is printed. Using get() method, a value is retrieved and printed.

package com.tutorialspoint;

import java.util.IdentityHashMap;

public class IdentityHashMapDemo {
   public static void main(String args[]) {
      
      // create hash map
      IdentityHashMap<Integer,Integer> newmap = new IdentityHashMap<>();

      // populate hash map
      newmap.put(1, 1);
      newmap.put(2, 2);
      newmap.put(3, 3); 

      System.out.println("Initial map elements: " + newmap);

      System.out.println("Value: " + newmap.get(1));
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

Initial map elements: {2=2, 3=3, 1=1}
Value: 1

Getting a Value from an IdentityHashMap of Integer, String Pair Example

The following example shows the usage of Java IdentityHashMap get() method to get a value based on a key from a Map. We've created a Map object of Integer,String pairs. Then few entries are added, map is printed. Using get() method, a value is retrieved and printed.

package com.tutorialspoint;

import java.util.IdentityHashMap;

public class IdentityHashMapDemo {
   public static void main(String args[]) {
      
      // create hash map
      IdentityHashMap<Integer,String> newmap = new IdentityHashMap<>();

      // populate hash map
      newmap.put(1, "tutorials");
      newmap.put(2, "point");
      newmap.put(3, "is best"); 

      System.out.println("Initial map elements: " + newmap);

      System.out.println("Value: " + newmap.get(1));
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

Initial map elements: {2=point, 3=is best, 1=tutorials}
Value: tutorials

Getting a Value from an IdentityHashMap of Integer, Object Pair Example

The following example shows the usage of Java IdentityHashMap get() method to get a value based on a key from a Map. We've created a Map object of Integer,Student pairs. Then few entries are added, map is printed. Using get() method, a value is retrieved and printed.

package com.tutorialspoint;

import java.util.IdentityHashMap;

public class IdentityHashMapDemo {
   public static void main(String args[]) {
      
      // create hash map
      IdentityHashMap<Integer,Student> newmap = new IdentityHashMap<>();

      // populate hash map
      newmap.put(1, new Student(1, "Julie"));
      newmap.put(2, new Student(2, "Robert"));
      newmap.put(3, new Student(3, "Adam"));

      System.out.println("Initial map elements: " + newmap);

      System.out.println("Value: " + newmap.get(1));
   }    
}
class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
}

Output

Let us compile and run the above program, this will produce the following result.

Initial map elements: {1=[ 1, Julie ], 3=[ 3, Adam ], 2=[ 2, Robert ]}
Value: [ 1, Julie ]