Goofy.java

Below is the syntax highlighted version of Goofy.java from §2.5 Sorting Applications.

/******************************************************************************
 *  Compilation:  javac Goofy.java
 *  Execution:    java Goofy N
 *  Dependencies: StdOut.java StdIn.java
 *
 *  Read strings from standard input and sort them using an algorithm
 *  of Jim Huggins.
 *
 ******************************************************************************/


public class Goofy {

    public static void sort(Comparable[] a) {
        sort(a, 0, a.length-1);
    }

    public static void sort(Comparable[] a, int lo, int hi) {
        if (lo >= hi) return;
        sort(a, lo, hi-1);     // first n-1 items
        if (less(a[hi], a[hi-1])) {
            exch(a, hi-1, hi);
            sort(a, lo, hi-1);  // first n-1 items
        }
    }

   /***************************************************************************
    *  Helper sorting functions.
    ***************************************************************************/

    // is v < w ?
    private static boolean less(Comparable v, Comparable w) {
        return v.compareTo(w) < 0;
    }

    // exchange a[i] and a[j]
    private static void exch(Object[] a, int i, int j) {
        Object swap = a[i];
        a[i] = a[j];
        a[j] = swap;
    }


 /***********************************************************************
    *  Check if array is sorted - useful for debugging.
    ***************************************************************************/
    private static boolean isSorted(Comparable[] a) {
        for (int i = 1; i < a.length; i++)
            if (less(a[i], a[i-1])) return false;
        return true;
    }

   // print array to standard output
    private static void show(Comparable[] a) {
        for (int i = 0; i < a.length; i++) {
            StdOut.println(a[i]);
        }
    }

    /**
     * Reads in a sequence of strings from standard input; insertion sorts them;
     * and prints them to standard output in ascending order.
     *
     * @param args the command-line arguments
     */
    public static void main(String[] args) {
        String[] a = StdIn.readAllStrings();
        Goofy.sort(a);
        show(a);
        assert isSorted(a);
    }

}