Why can't I liberally use "'==" in Java like other programming languages?

 == tests for reference equality (whether they are the same object).

.equals() tests for value equality (whether they are logically "equal").

Objects.equals() checks for nulls before calling .equals() so you don't have to (available as of JDK7, also available in Guava).

Consequently, if you want to test whether two strings have the same value you will probably want to use Objects.equals().

---

// These two have the same value
new String("test").equals("test") // --> true 

// ... but they are not the same object
new String("test") == "test" // --> false 

// ... neither are these
new String("test") == new String("test") // --> false 

// ... but these are because literals are interned by 
// the compiler and thus refer to the same object
"test" == "test" // --> true 

// ... but you should really just call Objects.equals()
Objects.equals("test", new String("test")) // --> true
Objects.equals(null, "test") // --> false

---

You almost always want to use Objects.equals(). In the rare situation where you know you're dealing with interned strings, you can use ==.

reference permalink: SO Answers

---

example:

 if(Objects.equals(pwd, lm.getEnteredPwd()) &&
                Objects.equals(un, lm.getEnteredUn())){
            lm.allowLogin(v);
        }

---