Difference Between == Operator and equals() Method in Java (original) (raw)

Last Updated : 4 Jan, 2025

In Java, the equals() method and the == operator are used to compare objects. The main difference is that **string equals() method compares the _content equality of two strings while the **== operator compares the reference or memory location of objects in a heap, whether they point to the same location or not.

**Example:

Java `

// the concept of .equals() and == operator public class Geeks { public static void main(String[] args) {

    String s1 = "HELLO";
    String s2 = "HELLO";
    String s3 =  new String("HELLO");

    System.out.println(s1 == s2);
    System.out.println(s1 == s3); 
    System.out.println(s1.equals(s2));
    System.out.println(s1.equals(s3)); 
}

}

`

Output

true false true true

**Explanation: When we use the == operator for s1 and s2 comparison, the result is true as both have the same addresses in the String constant pool.

.equals() Method vs == in Java

Equality Operator(==)

The == operator checks **reference equality for objects and **value equality for primitives.

**Example 1:

Java `

// == operator for compatible data types class Geeks { public static void main(String[] args) {

      // integer-type
    System.out.println(10 == 20);

    // char-type
    System.out.println('a' == 'b');

    // char and double type
    System.out.println('a' == 97.0);

    // boolean type
    System.out.println(true == true);
}

}

`

Output

false false true true

**Example 2: If we apply == for object types then, there **should be compatibility between argument types (either child to parent or parent to child or same type). Otherwise, we will get a compile-time error.

Java `

// == operator for incompatible data types class Geeks { public static void main(String[] args) {

    Thread t = new Thread();
    Object o = new Object();
    String s = new String("GEEKS");

    System.out.println(t == o);
    System.out.println(o == s);
  
    // uncomment the below print 
    // statement to see the error.
   // System.out.println(t==s);  
}

}

`

**Output:

./Test.java:15: error: incomparable types: Thread and String
System.out.println(t==s);
^
1 error

String equals() Method

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

**Example:

Java `

public class Geeks { public static void main(String[] args) {

      // Create two new Thread objects
    Thread t1 = new Thread();
    Thread t2 = new Thread();
    
      // Assign t3 to reference same
      // Thread object as t1
    Thread t3 = t1;

    // Create two String Objects with
      // Same content
    String s1 = new String("GEEKS");
    String s2 = new String("GEEKS");

    System.out.println(t1 == t3);
    System.out.println(t1 == t2);
    System.out.println(s1 == s2);

    System.out.println(t1.equals(t2));
    System.out.println(s1.equals(s2));
}

}

`

Output

true false false false true

**Java String Pool and Memory

• **String Pool: When two strings have the same content and are created without the new keyword, they point to the same memory location in the pool.
• Heap: Strings created using the new keyword always allocate new memory.

String s1 = "HELLO"; // String pool

String s2 = new String("HELLO"); // Heap