Java HashMap get() Method

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Description

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

Declaration

Following is the declaration for java.util.HashMap.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 the value to which the specified key is mapped, or null if this map contains no mapping for the key.

Exception

NA

Getting a Value for a Key from a Map of Integer, Integer Pair Example

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

package com.tutorialspoint;

import java.util.HashMap;

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

      // 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));
   }
}

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

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

Getting a Value for a Key from a Map of Integer, String Pair Example

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

package com.tutorialspoint;

import java.util.HashMap;

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

      // 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));
   }
}

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

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

Getting a Value for a Key from a Map of Integer, Student Pair Example

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

package com.tutorialspoint;

import java.util.HashMap;

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

      // 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 + " ]";
   }
}

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

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