Foo.java

public class Foo implements Cloneable {
  static class Bar {
    public int i;
    public Bar() { }
  }
  static class Qux {
    public int a[];
    public int b;
    public Qux() { }
  }

  public int x;
  public Foo.Bar y;
  public Foo.Qux z;

  /**
   * do not worry about this.
   */
  public Foo clone(){
    try {
      return (Foo)(super.clone());
    } catch (CloneNotSupportedException e){
      System.err.println("go home");
    }
    throw new RuntimeException("go home sally!");
  }  

  /**
   * Question 3.
   */
  public static Foo deepcopy(final Foo original){
    Foo shallowcopy = original.clone();  // don't worry about this line
    
    // -- start here
    Foo deepcopy = new Foo();

    deepcopy.x = shallowcopy.x;

    deepcopy.y = new Bar();
    deepcopy.y.i = shallowcopy.y.i;

    deepcopy.z = new Qux();
    deepcopy.z.a = new int[shallowcopy.z.a.length];
    System.arraycopy(shallowcopy.z.a,0,deepcopy.z.a,0,shallowcopy.z.a.length);
    deepcopy.z.b = shallowcopy.z.b;

    // -- end here

    return deepcopy;

  }

  public String toString()
  {
    StringBuffer s = new StringBuffer();

    s.append("[Foo]\n");

    s.append("\tx = " + this.x + "\n");

    s.append("\ty = ");
    if (y == null) {
      s.append("null");
    }
    else {
      s.append("{\n");
      s.append("\t\ti = " + y.i + ", \n");
      s.append("\t}");
    }
    s.append("\n");

    s.append("\tz = ");
    if (z == null) {
      s.append("null");
    }
    else {
      s.append("{\n");
      s.append("\t\ta = ");
      if (z.a == null) {
        s.append("null");
      }
      else{
        s.append(java.util.Arrays.toString(z.a));
        /*
         * for(int i=0; i < z.a.length; i++){
         *   s.append(z.a[i]+" ");
         * }
         */
      } s.append(", \n");
      s.append("\t\tb = " + z.b + "\n");
      s.append("\t}");
    }
    s.append("\n");

    return s.toString();
  }

  public static void main(String[] args)
  {
    testDeepCopy();
  }
  public static void testDeepCopy(){
    Foo f = new Foo();
    f.x = -1;
    f.y = new Foo.Bar();
    f.y.i = -23523;
    f.z = new Foo.Qux();
    f.z.a = new int[] {1324,12412,2435235,234,123};
    f.z.b = 300;
    System.out.println("Here is f");
    System.out.println(f);

    Foo f_deepcopy = Foo.deepcopy(f);
    System.out.println("\n\nhere is f_deepcopy");
    System.out.println(f_deepcopy);


    System.out.println("\n\nmaking changes to f...");
    f.x = 100;
    f.y.i = 101;
    f.z.a = new int[]{102,100,100,100};
    f.z.b = 103;

    System.out.println("\n\nHere is f");
    System.out.println(f);

    System.out.println("\n\nhere is f_deepcopy");
    System.out.println(f_deepcopy);


  }
  public static void testToString(){
    Foo f = new Foo();
    System.out.println(f);

    f.x = 1;
    f.y = new Foo.Bar();
    f.z = new Foo.Qux();
    System.out.println(f);

    f.z.a = new int[] { 1, 2, 3, 4, 5, 5, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7 };
    System.out.println(f);
  }
}