Java Hashtable equals() Method

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Description

The Java Hashtable equals(Object o) method is used to compare the specified Object with this Hashtable for equality.

Declaration

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

public boolean equals(Object o)

Parameters

o − This is the object to be compared for equality with this Hashtable.

Return Value

The method call returns 'true' if the specified Object is equal to this Hashtable.

Exception

NA

Checking Equality of HashTables of Integer, Integer Pair Example

The following example shows the usage of Java Hashtable equals() method to check if two Hashtable objects are equal or not. We've created two Hashtable objects of Integer,Integer pairs. Then few entries are added to hashtables and then using equals() method, tables are compared.

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<>();
      Hashtable<Integer,Integer> hashtable1 = new Hashtable<>();
	  
      // populate hash table
      hashtable.put(1, 1);
      hashtable.put(2, 2);
      hashtable.put(3, 3); 
	  
	  // populate hash table
      hashtable1.put(1, 1);
      hashtable1.put(2, 2);
      hashtable1.put(3, 3); 

      System.out.println("hashtables are same: " + hashtable.equals(hashtable1));
   }    
}

Output

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

hashtables are same: true

Checking Equality of HashTables of Integer, String Pair Example

The following example shows the usage of Java Hashtable equals() method to check if two Hashtable objects are equal or not. We've created two Hashtable objects of Integer,String pairs. Then few entries are added to hashtables and then using equals() method, tables are compared.

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<>();
      Hashtable<Integer,String> hashtable1 = new Hashtable<>();

      // populate hash table
      hashtable.put(1, "tutorials");
      hashtable.put(2, "point");
      hashtable.put(3, "is best"); 
	  
      hashtable1.put(1, "tutorials");
      hashtable1.put(2, "point");
      hashtable1.put(3, "is best");

      System.out.println("hashtables are same: " + hashtable.equals(hashtable1));
   }    
}

Output

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

hashtables are same: true

Checking Equality of HashTables of Integer, Object Pair Example

The following example shows the usage of Java Hashtable equals() method to check if two Hashtable objects are equal or not. We've created two Hashtable objects of Integer,Student pairs. Then few entries are added to hashtables and then using equals() method, tables are compared.

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<>();
      Hashtable<Integer,Student> hashtable1 = 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"));
	  
      // populate hash table
      hashtable1.put(1, new Student(1, "Julie"));
      hashtable1.put(2, new Student(2, "Robert"));
      hashtable1.put(3, new Student(3, "Adam"));

      System.out.println("hashtables are same: " + hashtable.equals(hashtable1));
   }    
}
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 + " ]";
   }
   
   @Override
   public boolean equals(Object obj) {
      if(obj == null) return false;
      Student s = (Student)obj;
      return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name);
   }

   @Override
   public int hashCode() {
      return rollNo + name.hashCode();
   }
}

Output

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

hashtables are same: true