Catch Exception and decimal format?

[Jason Beck]

Hi there,
This is a sample program which actually demonstrates the OOP on a time display program:
// Time abstract data type (ADT) definition
public class Time {
private int hour; // 0 - 23 (attributes)
private int minute; // 0 - 59 (attributes)
private int second; // 0 - 59 (attributes)
// Time constructor initializes each data member to zero.
// Ensures all Time objects start in a consistent state.
public Time( ) { hour = 0; minute = 0; second = 0; }
// set a new Time value hour, minute and second
public void setTime(int h, int m, int s)
{ hour = h; minute = m; second = s; }
// Print time in standard format
public void printStandard( ) {
System.out.print( hour + ":" + minute + ":" + second);
if (hour < 12 )
System.out.println(" AM");
else
System.out.println(" PM");
}
// Driver to test simple class Time
public static void main( String args[ ] ) {
Time t = new Time( ); // instantiate object t of class time
System.out.print("\nThe initial standard time is ");
t.printStandard( );
t.setTime(13, 27, 6);
System.out.print("\nStandard time after setTime is ");
t.printStandard( );
t.setTime(99, 99, 99); // attempt invalid settings
System.out.print("\nAfter attempting invalid settings: ");
t.printStandard( );
}
}
My question is:
1.) The setTime method shown above does not check for error. For example hour must be 0-23, minutes must be 0-59 and finally seconds must be 0-59.
I was told that a catch exception method can do the job. However I do not know how to do that. Can anyone please teach me how to do that?
2.) How can I display the time in military format like 9:40:12 am as 094012 and 9:40:12 pm as 214012?
3.) How can I modify the method printStandard to print time in 2 digit format: eg 9:3:5 am should be displayed as 9:03:05 am. I was told that the decimal format method should do the trick.
Can anyone help me out here? You assistance would be greatly appreciated as I need to prepare for my upcoming finals. Thank you.

[Stefan Wagner]

Originally posted by Jason Beck:

public void setTime(int h, int m, int s)
{ hour = h; minute = m; second = s; }

1.) The setTime method shown above does not check for error. For example hour must be 0-23, minutes must be 0-59 and finally seconds must be 0-59.
I was told that a catch exception method can do the job. However I do not know how to do that. Can anyone please teach me how to do that?

public void setTime(int h, int m, int s) throws TimeOutOfRangeException
{ 
   if (h < 0 || h > 23) throw new  TimeOutOfRangeException ("Hour out of range! " + h);
   if (m < 0 || m > 59) throw new  TimeOutOfRangeException ("Minute out of range! " + m);
   // ...
   hour = h; minute = m; second = s; 
}
class TimeOutOfRangeException extends Exception
{ 
    TimeOutOfRangeException (String msg)
    {
         super (msg);
    }
}

2.) How can I display the time in military format like 9:40:12 am as 094012 and 9:40:12 pm as 214012?

// Print time in standard format
public void printStandard( ) 
{
    int h = hour;
    String postfix  = "AM";
    if (hour > 12)
    { 
        h -=12; // your method printed '11 AM' or '23 PM'
        postfix = "PM";
    }
    // your method call started with an int (h), I guess this will fail.
    System.out.print( "" + h + ":" + minute + ":" + second + " "+ postfix);
}

// Print time in mil format
public void print_mil ( ) 
{
    String h = "" + hour;
    if (hour < 10) h = "0" + hour;
    // analog for min, sec
    System.out.print (h + m + s);
}

3.) How can I modify the method printStandard to print time in 2 digit format: eg 9:3:5 am should be displayed as 9:03:05 am. I was told that the decimal format method should do the trick.
Can anyone help me out here? You assistance would be greatly appreciated as I need to prepare for my upcoming finals. Thank you.

I guess in java.text (or was it 'java.util.text'?) there are formatter methods.
Have a look at the api-docs.
Did I do your homework well?