MyTime.java

public class MyTime implements Cloneable {
  private int value;

  public MyTime(int hour, int min, int sec) {
    if (hour < 0 || min < 0 || min >= 60 || sec < 0 || sec >= 60)
      throw new IllegalArgumentException("illegal time "+hour+":"+min+":"+sec);
    this.value = hour * 3600 + min * 60 + sec;
  }

  public MyTime(int value) {
    if (value < 0)
      throw new IllegalArgumentException("illegal time "+value+" seconds");
    this.value = value;
  }
  
  public int getHour() {
    return value / 3600;
  }

  public int getMin() {
    return (value / 60) % 60;
  }

  public int getSec() {
    return value % 60;
  }

  public int getValue() 
  {
    return value;
  }

  public void increment() {
    value++;
  }

  public MyTime add(MyTime other) {
    value += other.value;
    return this;
  }

  public boolean equals(Object obj) {
    if (obj instanceof MyTime) {
      MyTime other = (MyTime)obj;
      return value==other.value;
    }
    else
      return false;
  }

  public int compareTo(MyTime t) {
    return value - t.value;
  }

  public int hashCode() {
    return value;
  }

  public String toString() {
    return getHour()+":"+getMin()+":"+getSec();
  }

  public Object clone() {
    return new MyTime(value);
  }
}