Timer in Java - few problems with mins/hours decrement

I am developing a Java countdown timer. I am totally new to Java though have done some C++ before so it's not all totally new. I am having problems with this - can anyone easily see what I have done wrong in the logic?

What is happening:

On run, if you enter in for example 23 in hours leave mins blank and put in 5 secs - the 5 secs should count to 0 - the mins should go to 59 and the hours to 22. However once the 5 secs elapses all digits go to zero.

If on the input box I enter though 23 hours 1 in minutes and 5 in secs - when the 5 has elapsed it changes to 22 hours 59 mins 59 secs so I know its nearly there (just hoping I may have missed something silly.

Finally the last problem with the logic - if I for example enter 30 mins 5 secs when the 5 have elapsed the mins go to 29 the secs go to 59 and continue counting down but the hours go to -1. Code below - sorry for long post but wanted to paint the scenarios - Thanks - Colly

Integer sec = new Integer (seconds.getText ());
Integer min = new Integer (minutes.getText ());
Integer hr = new Integer (hours.getText ());
int temp1 = sec.intValue ();
int temp2 = min.intValue ();
int temp3 = hr.intValue();

temp1--;
if (temp1 == -1 )
{
    temp1 = 59;
    temp2--;
    if (temp2 == 0 && temp3 != 0)
    {
        temp2 = 59;
    }
    temp3--;
}
hr = new Integer (temp3);
sec = new Integer (temp1);
min = new Integer (temp2)开发者_StackOverflow中文版;
hours.setText (hr.toString ());
minutes.setText (min.toString ());
seconds.setText (sec.toString ());
if (seconds.getText ().length () == 1)
    seconds.setText ("0" + seconds.getText ());

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Please don't do time counting manually, it is painful to write and painful to read. I don't even mention how it feels to debug it.

The Calendar class may be interesting:

Calendar c = Calendar.getInstance();
c.clear(); // To reset all fields
c.set(Calendar.HOUR_OF_DAY, 23);
c.set(Calendar.MINUTE, 0);
c.set(Calendar.SECOND, 5);

c.add(Calendar.SECOND, -1);

And you don't have to worry about counting.

---

Using Calendar for date/time is (despite its shortcomings) the right thing. There's a simple alternative here: Compute the total seconds like

int total = 3600 * hrs + 60 * min + sec;

decrement and decompose using

int x = total;
hrs = x / 3600;
x = x - 3600 * hrs;
min = x / 60;
x = x - 60 * min;
sec = x;

This is surely less error-prone than working on the parts, especially for more complicated operations. But again, I recommend using Calendar.

---

May it's because you are leaving the minutes text box blank. Can you try with a 0 there?

---

On run, if you enter in for example 23 in hours leave mins blank and put in 5 secs - the 5 secs should count to 0 - the mins should go to 59 and the hours to 22. However once the 5 secs elapses all digits go to zero.

I renamed your vars:

s--;
if (s == -1 )
{
    s = 59;
    m--;
    if (m == 0 && h != 0)
    {
        m = 59;
    }
    h--;
}

If the seconds are 0, you decrement minutes. Then you test something, but without further tests, you always decrement hours.

While the code doesn't do what it should, it doesn't do what you describe. Is this your real code?