String.equals versus == [duplicate]

Question

This code separates a string into tokens and stores them in an array of strings, and then compares a variable with the first home ... why isn't it working?

public static void main(String...aArguments) throws IOException {      String usuario = "Jorman";     String password = "14988611";      String strDatos = "Jorman 14988611";     StringTokenizer tokens = new StringTokenizer(strDatos, " ");     int nDatos = tokens.countTokens();     String[] datos = new String[nDatos];     int i = 0;      while (tokens.hasMoreTokens()) {         String str = tokens.nextToken();         datos[i] = str;         i++;     }      //System.out.println (usuario);      if ((datos[0] == usuario)) {         System.out.println("WORKING");     } } 

Answer 1

Use the string.equals(Object other) function to compare strings, not the == operator.

The function checks the actual contents of the string, the == operator checks whether the references to the objects are equal. Note that string constants are usually "interned" such that two constants with the same value can actually be compared with ==, but it's better not to rely on that.

if (usuario.equals(datos[0])) {     ... } 

NB: the compare is done on 'usuario' because that's guaranteed non-null in your code, although you should still check that you've actually got some tokens in the datos array otherwise you'll get an array-out-of-bounds exception.