Java Hashtable get() Method

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Description

The Java Hashtable get(Object key) method is used to get the value to which the specified key is mapped in this hashtable.

Declaration

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

public V get(Object key)

Parameters

key − This is the key in the hashtable.

Return Value

The method call returns the value to which the key is mapped in this hashtable.

Exception

NullPointerException − This is thrown if the key is null.

Getting a Value From a HashTable of Integer, Integer Pair Example

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

package com.tutorialspoint;

import java.util.Hashtable;

public class HashtableDemo {
   public static void main(String args[]) {
      
      // create hash table
      Hashtable<Integer,Integer> hashtable = new Hashtable<>();

      // populate hash table
      hashtable.put(1, 1);
      hashtable.put(2, 2);
      hashtable.put(3, 3); 

      System.out.println("Initial table elements: " + hashtable);

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

Output

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

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

Getting a Value From a HashTable of Integer, String Pair Example

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

package com.tutorialspoint;

import java.util.Hashtable;

public class HashtableDemo {
   public static void main(String args[]) {
      
      // create hash table
      Hashtable<Integer,String> hashtable = new Hashtable<>();

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

      System.out.println("Initial table elements: " + hashtable);

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

Output

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

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

Getting a Value From a HashTable of Integer, Object Pair Example

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

package com.tutorialspoint;

import java.util.Hashtable;

public class HashtableDemo {
   public static void main(String args[]) {
      
      // create hash table
      Hashtable<Integer,Student> hashtable = new Hashtable<>();

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

      System.out.println("Initial table elements: " + hashtable);

      System.out.println("Value: " + hashtable.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 table elements: {3=[ 3, Adam ], 2=[ 2, Robert ], 1=[ 1, Julie ]}
Value: [ 1, Julie ]