RandomPointInCircle.java

Below is the syntax highlighted version of RandomPointInCircle.java from §1.3 Conditionals and Loops.

/******************************************************************************
 *  Compilation:  javac RandomPointInCircle.java
 *  Execution:    java RandomPointInCircle
 *
 *  Prints a point chosen uniformly at random inside the circle centered
 *  at (0, 0) and of radius 1.
 *
 *  Uses rejection sampling and a do-while loop.
 *
 *  %  java RandomPointInCircle
 *  (0.14539046532309108,0.8977797581170848)
 *
 *  % java RandomPointInCircle
 *  (-0.6333174979488703,-0.49591305165817845)
 *
 ******************************************************************************/

public class RandomPointInCircle {

    public static void main(String[] args) {
        double x, y;
        do {
            // Scale x and y to be random in (-1, 1).
            x = 2.0 * Math.random() - 1.0;
            y = 2.0 * Math.random() - 1.0;
        } while (x*x + y*y > 1.0);

        // print (x, y)
        System.out.println("(" + x + "," + y + ")");
    }
}