equals method in math class and string class java code example

Example: java == vs equals

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) .equals() and == is that one is a method and other is operator.
2) We can use == operator for reference comparison (address comparison) 
and .equals() method for content comparison. 
 -> == checks if both objects point to the same memory location 
 -> .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.

// 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)); 
    } 
} 
Output:
false
true
  
Explanation: Here we are creating two (String) 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.