Question

Let’s say I have a class that makes a ball. In the constructor, it accepts a String to indicate the kind of ball, but I only want it to accept certain values like: "FOOTBALL", "BASEBALL", or "SOCCERBALL", so that if I pass my class to another developer and they go to use it in Eclipse it prompts them as to the accepted value. How would I do that? I have no idea if there’s a general technique I could use or what it might be called, so pointers to a tutorial or example would be welcome.

public class Ball {
    public Ball(String type){
        …
    }
}

Answer 1

Here’s a Ball class that defaults to FOOTBALL unless otherwise specified:

public class Ball {

    public static final int FOOTBALL = 0;
    public static final int BASEBALL = 1;
    public static final int SOCCERBALL = 2;

    int ball;

     public Ball(){
        this.ball = Ball.FOOTBALL;
     }// end constructor

    /**
     *  Class constructor.
     *
     * @param ball sets the ball value.<p>
     * <b>ball</b> must be one of the following: Ball.FOOTBALL, Ball.BASEBALL,
     *             Ball.SOCCERBALL.
     */
     public Ball(int ball){          
        setBall(ball);       
     }// end constructor

     public int getBall(){
         return ball;
     }// end getBall()

     public void setBall(int ball){          
         switch(ball){           
         case 1:
             this.ball = Ball.BASEBALL;
             break;
         case 2:
             this.ball = Ball.SOCCERBALL;
             break;
         default:
             this.ball = Ball.FOOTBALL;
             break;          
         }// end switch          
     }// end setBall()       
}// end class Ball

Edit:

I added doc comments for javadoc which I think is what you are looking for. Check this link out: How to Write Doc Comments for the Javadoc Tool