Tips for golfing in Java

Question

I know I know, not another tips question. But I'm rather surprised that this question hasn't already been posted. At any rate, are there any useful shortcuts that can be used especially in Java?

As shown below, import already adds at least 17 characters to a program.

import java.io.*;

I understand that the simple solution would be to use another language, but it seems to be a real challenge to shorten Java programs.

Answer 1

I don't know if you would consider this 'pure' Java, but Processing allows you to create programs with little initial setup (completed automatically).

For console output, you can have something as simple as:

println("hi"); //done

for graphical output, a little more:

void setup() {
  size(640,480);
}
void draw() {
  fill(255,0,0); //color used to fill shapes
  rect(50,50,25,25); //25x25 pixel square at x=50,y=50
}

Answer 2

With a static import:

import static java.lang.System.out;

you can save some boilerplate later, but you need multiple invocations to reach a payoff:

public static void main (String[] args) {
    out.println ("foo");    
    out.println ("bar");    
    out.println ("baz");    
}

Answer 3

The argument to main doesn't have to be called args, and you can cut some whitespace:

public static void main(String[]a){}

will do just fine.

Answer 4

If you use enum instead of class, you save one character.

enum NoClass {
    F, G, H;    
    public static void main (String[] args) {

    }
}

But you have to introduce at least one enum instance (F, G, H in this example) which have to payoff themselves.