Elegant and Concise code

Do it short but do it right !

1. Check the nullity

String color = "green";
if  ( color!=null && color.equals("red") ) {
    System.out.println("Sorry, red is forbidden !");
}

It is important to testing the nullity of an object before invoking a method on it. Null pointer exceptions (NPEs) are indeed among the most common (and irritating) faults raised in the code of object-oriented languages.

As a workaround, there exists a trick for rewriting the condition without having to test for nullity. Remember, the equals() method is symmetric (if a=b then b=a).

if ( "red".equals(color) ) {
    System.out.println("Sorry, red is forbidden !");
}

2. Shorten the condition

if ("red".equals(color) ||"yellow".equals(color) ||"blue".equals(color)) {

    System.out.println("This is a primary color");

}

I have sometimes met more experienced Java programmers shortening such long if statement with:

if ( "red|yellow|blue".indexOf(color)>= 0 ) {
    System.out.println("This is a primary color");
}