Difference between == and .equals() method in Java

In general both equals() and “==” operator in Java are used to compare objects to check equality but here are some of the differences between the two:

1. Main difference between .equals() method and == operator is that one is method and other is operator.
2. We can use == operators for reference comparison (address comparison) and .equals() method for content comparison. In simple words, == checks if both objects point to the same memory location whereas .equals() evaluates to the comparison of values in the objects.
3. If a class does not override the equals method, then by default it uses equals(Object o) method of the closest parent class that has overridden this method. See this for detail
4. Coding Example:
   filter_none

   edit
   close

   play_arrow

   link
   brightness_4
   code

   // Java program to understand  // the concept of == operator public class Test {     public static void main(String[] args)     {         String s1 = new String("HELLO");         String s2 = new String("HELLO");         System.out.println(s1 == s2);         System.out.println(s1.equals(s2));     } }

   chevron_right

   filter_none

   Output:

   false
   true
   

   Explanation: Here we are creating two objects namely s1 and s2.

   • Both s1 and s2 refers to different objects.
   • When we use == operator for s1 and s2 comparison then the result is false as both have different addresses in memory.
   • Using equals, the result is true because its only comparing the values given in s1 and s2.

Let us understand both the operators in detail:

Equality operator(==)

We can apply equality operators for every primitive types including boolean type. we can also apply equality operators for object types.

Output:

false
false
true
true

If we apply == for object types then, there should be compatibility between arguments types (either child to parent or parent to child or same type). Otherwise we will get compile time error.

Output:

false
false
// error: incomparable types: Thread and String

.equals()

In Java, string equals() method compares the two given strings based on the data/content of the string. If all the contents of both the strings are same then it returns true. If all characters are not matched then it returns false.

Output:

true
false
false
false
true

Explanation: Here we are using .equals method to check whether two objects contains the same data or not.

• In the above example, we are creating 3 Thread objects and 2 String objects.
• In the first comparison, we are checking that t1 == t3 or not. As we know that both t1 and t3 pointing to same object that’s why it returns true.
• In second comparison, we are using operator “==” for comparing the String Objects and not the contents of the objects. Here, both the objects are different and hence the outcome of this comparison is “False”
• When we are comparing 2 String objects by .equals() operator then we are checking that is both objects contains the same data or not.
• Both the objects contains the same String i.e. GEEKS that’s why it returns true.

This article is contributed by Bishal Kumar Dubey. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

Attention reader! Don’t stop learning now. Get hold of all the important Java and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready.