CODEWITHSUNDEEP
javatimeclock
Pauline Orr
Pauline Orr

Reputation: 123

Java Clock Advancing Time

Struggling with some java homework, why isn't this working? Advance brings in minutes. If its over 59 minutes then it adds to my hourly counter. Then I check to see if hours count over 12 to change the AM/PM status. This needs to repeatedly bring in numbers and continually add. I left out the other code as this is the part I'm supposed to be able to do.

public void advance(int advance) {
   int whichAmPm = 0;
   minute += advance;
   if (minute > 59) {
       hour++;
       minute = (minute - 60);
   }
   if (hour > 12) {
       hour = (hour - 12);
       whichAmPm++;
   }
   if (whichAmPm % 2 == 0) {
        amPm = amPm;
    } else if (whichAmPm % 2 !=0) {
        if (amPm == "AM") {
            amPm = amPm.replaceAll("A", "P");
         } else {
            amPm = amPm.replaceAll("P", "A");
     }
   }
   }

Upvotes: 1

Views: 1904

Answers (3)

Elliott Frisch
Elliott Frisch

Reputation: 201447

You need to loop (instead of using if statements). You can use -= (like x -= y) instead of x = x - y. And you compare Object types (like String) with .equals, == tests reference equality. Finally, you might use a ternary operator. I think you wanted something like,

public void advance(int advance) {
    int whichAmPm = 0;
    minute += advance;
    while (minute > 59) {
        hour++;
        minute -= 60;
        if (hour > 12) { // <-- this is safe because the above increments hour once
            hour -= 12;
            whichAmPm++;
        }
    }
    if (whichAmPm % 2 != 0) {
        amPm = amPm.equals("AM") ? "PM" : "AM";
    }
}

Upvotes: 1

WalterM
WalterM

Reputation: 2706

The problem with your method is that it won't work when you add 120 minutes. This is a simple way to achieve what you want with no if statements. 

public static final int AM = 0, PM = 1;
int hour = 0, minute = 0;
int am_pm = AM;

public void advance(int advance) {
    minute += advance;
    hour += minute / 60;
    minute %= 60;
    am_pm ^= (hour / 12 % 2);
    hour %= 12;
}

Upvotes: 1

MadProgrammer
MadProgrammer

Reputation: 347244

You could simply use some modular mathematics (but one can't discount the simplicity of a loop either)

int hour = 8;
int min  = 30;

int advance = 125;

min += advance % 60;
hour += advance / 60;

I'd also consider simplifying your am/pm decisions from... 

if (hour > 12) {
    hour = (hour - 12);
    whichAmPm++;
}
if (whichAmPm % 2 == 0) {
    amPm = amPm;
} else if (whichAmPm % 2 != 0) {
    if (amPm == "AM") {
        amPm = amPm.replaceAll("A", "P");
    } else {
        amPm = amPm.replaceAll("P", "A");
    }
}

to something more like...

if (hour > 12) {
    hour = (hour - 12);
    amPm = "PM";
} else {
    ampPM = "AM";
}

But that's just me

Upvotes: 1

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