if Tips

• Don't end the if part with a semi-colon. For example:

  if (x == 0);
      y = 0;
  

  will always execute the assignment statement and set y to 0.
  
  
• Remember to use the double equals sign (==), not just an equals sign.
  

• If you use =, the expression evaluates to the value that is assigned (the rvalue). For instance:

  if (x = false)
  

  assigns false to x, and will always evaluate to be false, and:

  if (x = true)
  

  will assign true to x, and will always evaluate to true.
  
  
• Remember, whitespace is for readability, so just because you have it indented properly does not mean it works that way. For instance:

  if (x >= 18)
      stringObj="more than 18";
      rc = 18;
  

  will always execute the assignment statement and set rc to 18.

• Remember, do NOT use relational operators with Objects; by this I mean class-objects that can be instantiated with new. Instead call methods, for instance equals().
• The == and != operators compare references (do they refer to the same object?), and does NOT compare their values (do they have the same values?); in most cases is not what you want.