Converting Military Time To Standard Time?

I have two classes. time_runner is used for testing my code.

This is what I'm using to test my code:
 
class time_runner
{
 public static void main(String str[]) throws IOException {
 Time time1 = new Time(14, 56);
System.out.println("time1: " + time1);
System.out.println("convert time1 to standard time: " + time1.convert());
System.out.println("time1: " + time1);
System.out.print("increment time1 five times: ");
time1.increment();

[code]....

The two constructors are "Time()", which is the default constructor that sets the time to 1200, and "Time(int h, int m)" Which says If h is between 1 and 23 inclusive, set the hour to h. Otherwise, set the hour to 0. If m is between 0 and 59 inclusive, set the minutes to m. Otherwise, set the minutes to 0. Those are my two constructors that I pretty much have down. The three methods however I'm having trouble with. The "String toString()" Returns the time as a String of length 4. The "String convert()" Returns the time as a String converted from military time to standard time. The "void increment()" Advances the time by one minute.

public class Time {
private int hour;
private int minute;
  public Time(int h, int m) {
if(h > 1 && h < 23)
hour = h;

[code]....