why if statement always return false

Question

I want to check it the first input argument is operator "+"

below is the code

if (args[0] == "+") {
    System.out.println("good");
} else {
    System.out.println("invalid expression");
}

but it always return false. something wrong with the code?

Answer 1

You should compare strings using str.equals(..) method and not ==, which compares object adresses.

if (args[0].equals("+")) {
  :
}