A string cannot be compared with == operator. It is always compared with equals() function.

Compare string:

class Replace 
{
    public static void main(String[] args) 
    {
        String s1 = "Hello";
        if(s1.replace('H','H').equals( "Hello")){
            System.out.println("yes"); 
        }
        else {
            System.out.println("No");
        }
        if(s1.replace("H", "H").equals("Hello")){
            System.out.println("yes");
        }
        else{
            System.out.println("No");
        }
    }
}