Java: How to compare Strings correctly

Yes, you have to take something into account. That is the difference between comparing with == and comparing with .equals().

• With == you are checking for the same reference, that is for example that two variables are pointing to the same object.
• With .equals() you are checking for the same value, that is for example whether two strings have the same content, independent from whether the object is also the same or not.

So, if you are in your case only interested in comparing the content or value of a string, you have to use .equals() instead of "==".

Your observation that "==" is sometimes working and sometimes not is probably because you have from time to time indeed compared strings having the same reference. However, if the string value is the same, but not the reference, the result of the == comparison was accordingly false.

Here is a small example demonstrating the difference:

String a = new String("abc");
String b = new String("abc");
String c = a;

if (a == b) {
  // FALSE because reference is not equal
}

if (a == c) {
  // TRUE because reference is the same
}

if (a.equals(b)) {
  // TRUE because content is the same
}

By the way, with .equals() you are always also checking for an identical uppercase and lowercase writing. If you do not want to consider the writing, you can use .equalsIgnoreCase() instead.
2016-07-11 at 17:29