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Having trouble developing incrementMinutesBy method

I am trying to create a digital clock an am currently trying to fix my incrementMinutesBy method. 
I need this method to increase both the minutes and if necessary the hours. I need the final this.minutes to be the sum of the previous this.minutes and the parameter, modulo the number of minutes in an hour.
I also need the final this.hours to be the sum of the previous this.minutes and the parameter, divided by the number of minutes in an hour. My method so far begins on line 94.
public class DigitalClock
{
private int currentHour;
private int currentMinutes;
public int getHour()
{
return currentHour;
}
public void setHour(int currentHour)
{
this.currentHour = currentHour;
}
public int getMinutes()
{
return currentMinutes;
}
public void setMinutes(int currentMinutes)
{
this.currentMinutes = currentMinutes;
}
public static final int HOUR_MAX = 23; // Refactored hourly max
public static final int HOUR_MIN = 0; // Refactored hourly min
public static final int MINUTES_MAX = 59; // Refactored minute max
public static final int MINUTES_MIN = 0; // Refactored minute min
public static final int TOTAL_NUMBERS_HOURS = 24;
public static final int TOTAL_NUMBERS_MINUTES = 60;
/**
* Creates a new digital clock with the time set at the given
* hours and minutes.
*
* #precondition 0 <= hour <= 23 AND 0 <= minutes <= 59
* #postcondition getHour()==hour AND getMinutes()==minutes
*
* #param hour the hour to set for the time
* #param minutes the minutes to set for the time
*/
public DigitalClock (int hour, int minutes) // 2-parameter constructor (parameters: int hour and int minutes)
{
// enforcing hourly preconditions using appropriate ranges
if (hour >= HOUR_MIN && hour <= HOUR_MAX){
currentHour = hour;
}
else {
currentHour = 0;
//throw an exception on invalid hour's input
throw new IllegalArgumentException("Invalid input for Hours");
}
// enforcing minute preconditions using appropriate ranges
if (minutes >= MINUTES_MIN && minutes <= MINUTES_MAX) {
currentMinutes = minutes;
}
else {
currentMinutes = 0;
//throw an exception on invalid minute's input
throw new IllegalArgumentException("Invalid input for Minutes");
}
}
/**
* Advances the entire clock by the given number of hours.
* If the hours advances past 23 they wrap around.
*
* #precondition hours >= 0
* #postcondition the clock has moved forward
* by the appropriate number of hours
*
* #param hours the number of hours to add
*/
public void incrementHoursBy(int hour)
{
int h = getHour()+hour; {
// if statement enforcing precondition
if(h>HOUR_MAX)
h%=TOTAL_NUMBERS_HOURS;
// increasing this.hours by the parameter
setHour(h);}
// if statement which prevents negative hours from being inputted
if (h<HOUR_MIN) {
throw new IllegalArgumentException("Invalid input. No negative hours");
}
}
public void incrementMinutesBy(int minutes) {
int m = getMinutes()+minutes;
m++;
if (m > MINUTES_MAX) {
m%=TOTAL_NUMBERS_MINUTES;
setMinutes(m);
}
if (m<MINUTES_MIN) {
throw new IllegalArgumentException("Invalid input. No negative minutes");
}
else
{
System.out.println("Minutes are: "+m);
}
}
public static void main(String args[])
{
DigitalClock obj=new DigitalClock(12, 15);
obj.incrementHoursBy(HOUR_MAX);
obj.incrementMinutesBy(MINUTES_MAX);
DigitalClockFormatter();
}
public static void DigitalClockFormatter() {
// method for class DigitalClockFormatter
}
}

To simplify the implementation, it's beter to save totalMinutes internaly, but not the separate hours and minutes.
public final class DigitalClock {
private static final int MINUTES_PER_HOUR = (int)TimeUnit.HOURS.toMinutes(1);
private static final int MINUTES_PER_DAY = (int)TimeUnit.DAYS.toMinutes(1);
private int totalMinutes;
public DigitalClock(int hour, int minutes) {
setHour(hour);
setMinutes(minutes);
}
public int getHour() {
return totalMinutes / MINUTES_PER_HOUR;
}
public int getMinutes() {
return totalMinutes % MINUTES_PER_HOUR;
}
public void setHour(int hour) {
if (hour < 0 || hour > 23)
throw new IllegalArgumentException("'hour' should be within [0;23]");
totalMinutes = (int)TimeUnit.HOURS.toMinutes(hour) + getMinutes();
}
public void setMinutes(int minutes) {
if (minutes < 0 || minutes > 59)
throw new IllegalArgumentException("'minutes' should be within [0;59]");
totalMinutes = (int)TimeUnit.HOURS.toMinutes(getHour()) + minutes;
}
public void incrementHoursBy(int hour) {
totalMinutes = withinDay((int)TimeUnit.HOURS.toMinutes(hour) + totalMinutes);
}
public void incrementMinutesBy(int minutes) {
totalMinutes = withinDay(totalMinutes + minutes);
}
private static int withinDay(int totalMinutes) {
totalMinutes %= MINUTES_PER_DAY;
if (totalMinutes < 0)
totalMinutes = MINUTES_PER_DAY + totalMinutes;
return totalMinutes;
}
#Override
public String toString() {
return String.format("%02d:%02d", getHour(), getMinutes());
}
}

I believe that your calculations can also be achieved by subtraction. Consider the following example.
If currentHour is 23 and you add two hours, then the result should be 1 (one).
23 + 2 = 25
25 % 24 = 1
25 - 24 = 1
Similarly for currentMinutes. However, for currentMinutes you also need to increment currentHour if the result of the increment (to currentMinutes) is greater than MINUTES_MAX. And when you increment currentHour you also need to check whether the incremented currentHour value is greater than HOUR_MAX. In other words, if currentHour is 23 and currentMinutes is 55 and you incrementMinutesBy(10), then:
55 + 10 = 65
65 - 60 = 5
Therefore currentMinutes is set to 5 and currentHour needs to be incremented. Therefore:
23 + 1 = 24
24 - 24 = 0
So currentHour needs to be set to 0 (zero).
Also, as explained in the book Java by Comparison, methods need to fail fast so the first thing you should do in both method incrementHoursBy and method incrementMInutesBy is to check the value of the method argument – and not the result of the calculation. After all, you wrote in the code comments that the pre-condition is that the method argument not be negative – even though I think it would be logical to be able to set the digital clock backwards. I mean that's what you do when daylight saving ends and the clocks get turned back one hour. But then again, with your [digital] clock, you could achieve the same result by invoking incrementHoursBy(HOUR_MAX)
Consider the following code:
public class DigitalClock {
private int currentHour;
private int currentMinutes;
public int getHour() {
return currentHour;
}
public void setHour(int currentHour) {
this.currentHour = currentHour;
}
public int getMinutes() {
return currentMinutes;
}
public void setMinutes(int currentMinutes) {
this.currentMinutes = currentMinutes;
}
public static final int HOUR_MAX = 23; // Refactored hourly max
public static final int HOUR_MIN = 0; // Refactored hourly min
public static final int MINUTES_MAX = 59; // Refactored minute max
public static final int MINUTES_MIN = 0; // Refactored minute min
public static final int TOTAL_NUMBERS_HOURS = 24;
public static final int TOTAL_NUMBERS_MINUTES = 60;
/**
* Creates a new digital clock with the time set at the given hours and minutes.
*
* #precondition 0 <= hour <= 23 AND 0 <= minutes <= 59
* #postcondition getHour()==hour AND getMinutes()==minutes
*
* #param hour the hour to set for the time
* #param minutes the minutes to set for the time
*/
public DigitalClock(int hour, int minutes) {
// enforcing hourly preconditions using appropriate ranges
if (hour >= HOUR_MIN && hour <= HOUR_MAX) {
currentHour = hour;
}
else {
currentHour = 0;
// throw an exception on invalid hour's input
throw new IllegalArgumentException("Invalid input for Hours");
}
// enforcing minute preconditions using appropriate ranges
if (minutes >= MINUTES_MIN && minutes <= MINUTES_MAX) {
currentMinutes = minutes;
}
else {
currentMinutes = 0;
// throw an exception on invalid minute's input
throw new IllegalArgumentException("Invalid input for Minutes");
}
}
/**
* Advances the entire clock by the given number of hours. If the hours advances
* past 23 they wrap around.
*
* #precondition hours >= 0
* #postcondition the clock has moved forward by the appropriate number of hours
*
* #param hours the number of hours to add
*/
public void incrementHoursBy(int hour) {
// if statement which prevents negative hours from being inputted
if (hour < HOUR_MIN || hour > HOUR_MAX) {
throw new IllegalArgumentException("Invalid input. Between 0 & 23");
}
int h = currentHour + hour;
// if statement enforcing precondition
if (h > HOUR_MAX) {
h -= TOTAL_NUMBERS_HOURS;
}
// increasing this.hours by the parameter
setHour(h);
}
public void incrementMinutesBy(int minutes) {
if (minutes < MINUTES_MIN || minutes > MINUTES_MAX) {
throw new IllegalArgumentException("Invalid input. Between 0 & 59");
}
int m = getMinutes() + minutes;
if (m > MINUTES_MAX) {
incrementHoursBy(1);
m -= TOTAL_NUMBERS_MINUTES;
setMinutes(m);
}
}
public static void main(String args[]) {
DigitalClock obj = new DigitalClock(22, 55);
obj.incrementHoursBy(1);
obj.incrementMinutesBy(10);
DigitalClockFormatter(obj);
}
public static void DigitalClockFormatter(DigitalClock dc) {
System.out.printf("%02d:%02d", dc.getHour(), dc.getMinutes());
}
}
Running above code displays:
00:05
Alternatively, you could use the date-time API.
import java.time.LocalTime;
public class DigiClok {
private LocalTime clock;
public DigiClok(int hour, int minute) {
clock = LocalTime.of(hour, minute); // throws java.time.DateTimeException if invalid arguments
}
public int getHour() {
return clock.getHour();
}
public void setHour(int currentHour) {
// class 'java.time.LocalTime' is immutable.
int minute = clock.getMinute();
clock = LocalTime.of(currentHour, minute);
}
public int getMinutes() {
return clock.getMinute();
}
public void setMinutes(int currentMinutes) {
int hour = clock.getHour();
clock = LocalTime.of(hour, currentMinutes);
}
public boolean equals(Object obj) {
boolean equal = this == obj;
if (!equal) {
if (obj instanceof DigiClok) {
DigiClok other = (DigiClok) obj;
equal = clock.equals(other.clock);
}
}
return equal;
}
public int hashCode() {
return clock.hashCode();
}
public String toString() {
return clock.toString();
}
public void incrementHoursBy(int hour) {
clock = clock.plusHours(hour); // also handles negative 'hour'
}
public void incrementMinutesBy(int minutes) {
clock = clock.plusMinutes(minutes); // also handles negative 'minute'
}
public static void main(String[] args) {
DigiClok obj = new DigiClok(22, 55);
obj.incrementHoursBy(1);
obj.incrementMinutesBy(10);
System.out.println(obj);
}
}

Is there something wrong with the setZone method?

I'm making a program that extends the clock to feature the names of the time zones. The derived class needs to have a static String array data member with values: EST, CST, MST, PST, EDT, CDT, MDT, PDT, a zone data member, a default constructor, a constructor with parameters, the setZone() method, the getZone() method, the printTime() method, the toString(), the equals() method, a makeCopy() method, and a getCopy() method.
public class Clock {
private int hr;
private int min;
private int sec;
public Clock() {
hr = 0;
min = 0;
sec = 0;
}
public Clock(int hours, int minutes, int seconds) {
if (0 <= hours && hours < 24) {
hr = hours;
}
else {
hr = 0;
}
if (0 <= minutes && minutes < 60) {
min = minutes;
}
else {
min = 0;
}
if (0 <= seconds && seconds < 60) {
sec = seconds;
}
else {
sec = 0;
}
}
public Clock(Clock otherClock) {
hr = otherClock.hr;
min = otherClock.min;
sec = otherClock.sec;
}
public void setTime(int hours, int minutes, int seconds) {
if (0 <= hours && hours < 24) {
hr = hours;
}
else {
hr = 0;
}
if (0 <= minutes && minutes < 60) {
min = minutes;
}
else {
min = 0;
}
if (0 <= seconds && seconds < 60) {
sec = seconds;
}
else {
sec = 0;
}
}
public int getHours() {
return hr;
}
public int getMinutes() {
return min;
}
public int getSeconds() {
return sec;
}
public void printTime() {
if (hr < 10) {
System.out.print("0");
}
System.out.print(hr + ":");
if (min < 10) {
System.out.print("0");
}
System.out.print(min + ":");
if (sec < 10) {
System.out.print("0");
}
System.out.print(sec);
}
public void incrementHours() {
hr++;
if (hr > 23) {
hr = 0;
}
}
public void incrementMinutes() {
min++;
if (min > 59) {
min = 0;
incrementHours();
}
}
public void incrementSeconds() {
sec++;
if (sec > 59) {
sec = 0;
incrementMinutes();
}
}
public boolean equals(Clock otherClock) {
return (hr == otherClock.hr && min == otherClock.min && sec == otherClock.sec);
}
public void makeCopy(Clock otherClock) {
hr = otherClock.hr;
min = otherClock.min;
sec = otherClock.sec;
}
public Clock getCopy() {
Clock temp = new Clock();
temp.hr = hr;
temp.min = min;
temp.sec = sec;
return temp;
}
public String toString() {
String str = "";
if (hr < 10) {
str = "0";
}
str += hr + ":";
if (min < 10) {
str += "0";
}
str += min + ":";
if (sec < 10) {
str += "0";
}
str += sec;
return str;
}
}
class ExtClock extends Clock {
static String[] timeZone = {"EST", "CST", "MST", "PST", "EDT", "CDT", "MDT", "PDT"};
private String zone;
public ExtClock() {
super();
zone = "";
}
public ExtClock(int hours, int minutes, int seconds, String tz) {
super(hours, minutes, seconds);
zone = tz;
}
public void setZone(int hours, int minutes, int seconds, String tz) {
setTime(hours, minutes, seconds);
zone = tz;
}
public String getZone() {
return zone;
}
public void printTime() {
super.printTime();
System.out.println(" " + zone);
}
public String toString() {
return super.toString() + " " + zone;
}
public boolean equals(ExtClock otherClock) {
return super.equals(otherClock) && zone.equalsIgnoreCase(otherClock.zone);
}
}
public class ExtClockTest {
public static void main(String[] args) {
ExtClock myExtClock = new ExtClock(5,4,30,"EST");
ExtClock yourExtClock = new ExtClock(0,0,0,"");
setZone.yourExtClock(5,45,16,"CDT");
}
}
The derived class compiles fine, but the ExtClockTest program wouldn't compile because it says that it cannot find the symbol. Am I doing something wrong?

You have put the method before the object.
setZone.yourExtClock(5,45,16,"CDT");
It should be:
Obj.method()
yourExtClock.setZone(5,45,16,"CDT");

How do I call one constructor from another in Java? (beginner example)

First of all, I have read this question which i am aware is dealing with the same fundamental problem I am having.
Nevertheless, I am unable to apply the solution to my own particular problem.
in the following example i have a few overloaded Clock constructors. The error occurs in the case where I am trying to create a Clock from string input.
Does anyone have any tips for the correct implementation of the constructor call?
Code:
public class Clock
{
public static void main(String[] args)
{
Clock testClock = new Clock(153, 26);
System.out.println("Input: Clock(153, 26)");
System.out.println(testClock.toString());
Clock testClock2 = new Clock(9000);
System.out.println("Input: Clock(9000)");
System.out.println(testClock2.toString());
Clock testClock3 = new Clock(23:59);
System.out.println("Input: Clock(23:59)");
System.out.println(testClock3.toString());
System.out.println("Input: testClock2.add(20)");
System.out.println(testClock2.add(20));
System.out.println("input: testClock.add(testClock2)");
System.out.println(testClock.add(testClock2).toString());
}
// Constructors
public Clock(int min, int h)
{
this.min += min%60;
h += min/60;
this.h += h%24;
}
public Clock(int min)
{
this.min += min%60;
this.h += (min/60)%24;
}
public Clock (String theTime)
{
int minutes = Integer.parseInt(theTime.substring(0,1));
int hours = Integer.parseInt(theTime.substring(3,4));
Clock stringClock = new Clock(minutes, hours);
return stringClock; //error occurs *********************
}
private int h;
private int min;
public int getMin() {
return min;
}
public int getH() {
return h;
}
public Clock add(int min)
{
int newMin = this.min + min;
int newH = this.h;
Clock newClock = new Clock(newMin, newH);
return newClock;
}
public Clock add(Clock c)
{
int newMin = this.min + c.min;
int newH = this.h + c.h;
Clock newClock = new Clock(newMin, newH);
return newClock;
}
public String toString()
{
String theTime = "";
if (this.h < 10)
{
theTime += "0" + this.h;
}
else
{
theTime += this.h;
}
theTime += ":";
if (this.min < 10)
{
theTime += "0" + this.min;
}
else
{
theTime += this.min;
}
return theTime;
}
}

You could call this but it should be very first statement such as:
public Clock (String theTime)
{
this(
Integer.parseInt(theTime.substring(0,1)),
Integer.parseInt(theTime.substring(3,4))
);
}
Alternatively you could use a static factory method:
public static Clock parseHHMM(String theTime)
{
int hh = Integer.parseInt(theTime.substring(0,1));
int mm = Integer.parseInt(theTime.substring(3,4));
return new Clock(hh, mm);
}
I prefer the latter, it is common approach in Java, e.g. here.

There is also a problem with that line:
Clock testClock3 = new Clock(23:59);
If you want the argument to be treated as String, you should surround the value passed as argument with quotes, like this:
Clock testClock3 = new Clock("23:59");
, because when you don't change the look of parameter passed, it won't compile.

You could consider splitting theTime at the semicolon":" so as to obtain an array of two integers, the first being the hour and the second being the minutes. Take a look
public Clock (String theTime)
{
this(Integer.parseInt(theTime.split(":")[1],
Integer.parseInt(theTime.split(":")[0]);
}
hope this helps

having trouble picking the right formal parameter for a boolean method

Under the comment version 4, i am trying to create a method named equals that will test the hours, minutes, and seconds. The formal parameter is used again in the return statement. I know i should have it in the ______.hours format, hours being the instance variable used to test and produce the true or false, but i don't know what should go before the period as the formal parameter. Any suggestions/explanations would be appreciated greatly.
public class Clock
{
private static final byte DEFAULT_HOUR = 0,
DEFAULT_MIN = 0,
DEFAULT_SEC = 0,
MAX_HOURS = 24,
MAX_MINUTES = 60,
MAX_SECONDS = 60;
// ------------------
// Instance variables
// ------------------
private byte seconds,
minutes,
hours;
public Clock (byte hours , byte minutes , byte seconds )
{
setTime(hours, minutes, seconds);
}
public Clock ( )
{
setTime(DEFAULT_HOUR, DEFAULT_MIN, DEFAULT_SEC);
}
public void setTime ( byte hours, byte minutes, byte seconds )
{
this.hours = hours;
this.minutes = minutes;
this.seconds = seconds;
// hours
if (DEFAULT_HOUR >= 0 && DEFAULT_HOUR <= 29)
{
}
else
{
hours = DEFAULT_HOUR;
}
// minutes
if (DEFAULT_MIN >= 0 && DEFAULT_MIN <= 59)
{
}
else
{
minutes = DEFAULT_MIN;
}
// seconds
if (DEFAULT_SEC >= 0 && DEFAULT_SEC <= 59)
{
}
else
{
seconds = DEFAULT_SEC;
}
}
//--------------------------
// Version 3 mutator methods
//--------------------------
public void incrementSeconds()
{
seconds += 1;
if (seconds >= 59)
{
seconds = DEFAULT_SEC;
incrementMinutes();
}
}
public void incrementMinutes()
{
minutes += 1;
if (minutes >= 59)
{
minutes = DEFAULT_MIN;
incrementHours();
}
}
public void incrementHours()
{
hours += 1;
if (hours >= 23)
{
hours = DEFAULT_HOUR;
}
}
//----------
// Version 4
//----------
public boolean equals(Clock your_clock)
{
return boolean your_clock.hours;
}
//----------
// Version 2
//----------
public String toString()
{
final byte MIN_2DIGITS = 10;
String str = "";
// my input
if (hours < MIN_2DIGITS)
{
str += "0" + hours + ":" ;
}
else
str += hours + ":";
if (minutes < MIN_2DIGITS)
{
str += "0" + minutes + ":" ;
}
else
str += minutes + ":";
if (seconds < MIN_2DIGITS)
{
str += "0" + seconds;
}
else
str += seconds;
//end of my input
return str;
}
} // End of class definition

If you're trying to find equality between the parameter Clock and the caller Clock, I would do the following
public boolean equals(Clock another_clock) {
// Check if 'this' is equal to 'another_clock'
// 1. If you're checking if the pointer is the same
return another_clock.equals(this);
// 2. If you're checking if time is the same (You probably need to create getter/setter methods or change privacy for these fields)
return another_clock.hours == this.hours &&
another_clock.minutes == this.minutes &&
another_clock.seconds == this.seconds;
}
Or something along those lines.

Java PriorityQueue not working?

I have an Event class which uses the PriorityQueue and a Time class that I defined myself to use with the Event class.
static class Event implements Comparable<Event>{
Customer customer;
Time eventTime;
char eventType;
public int compareTo(Event e){
int n = e.eventTime.compareTo(eventTime);
int compare = 0;
if(n < 0){
compare = -1;
}
else if(n == 0){
compare = 0;
}
else if(n > 0){
compare = 1;
}
return compare;
}
}
class Time{
private int hour;
private int minute;
private boolean isMorning;
public Time(){
hour = 0;
minute = 0;
isMorning = true;
}
public Time(int h, int m, boolean morning){
hour = h;
minute = m;
isMorning = morning;
}
public void setTime(int h, int m, boolean morning){
hour = h;
minute = m;
isMorning = morning;
}
public int getHour(){
return hour;
}
public int getMinute(){
return minute;
}
public boolean isAM(){
return isMorning;
}
public String toString(){
String AM = "";
String min = "";
if(minute < 10){
min = ("0" + minute);
}
else{
min = ("" + minute);
}
if(isMorning){
AM = "AM";
}
else{
AM = "PM";
}
return ("" + hour + ":" + min + " " + AM);
}
public Time plus(int n){
Time newTime = new Time();
boolean newMorning = false;
int minutes = minute + n;
int newHour = minutes/60;
int newMinutes = minutes%60;
hour = hour + newHour;
if(hour > 12){
hour = hour - 12;
if(isMorning){
newMorning = false;
}
else{
newMorning = true;
}
}
newTime.setTime(hour, newMinutes, newMorning);
return newTime;
}
public int timeDifference(Time t){
int n = totalMinutes();
int m = t.totalMinutes();
return m - n;
}
public int compareTo(Time t){
int n = totalMinutes();
int m = t.totalMinutes();
int compare = 0;
if(n < m){
compare = -1;
}
else if(n == m){
compare = 0;
}
else if(n > m){
compare = 1;
}
return compare;
}
private int totalMinutes(){
int tempMinute = 0;
if(!isMorning){
if(hour == 12){
}
else{
hour = hour + 12;
tempMinute = (hour*60) + minute;
}
}
else{
if(hour == 12){
tempMinute = minute;
}
else{
tempMinute = (hour*60) + minute;
}
}
return tempMinute;
}
}
This isn't all of my code as I have others just holding the values that will later be inserted into the Event queue. When I check the time outside of the Event queue it matches the time that it should be, say I have a Time object as 11:22 AM, but when I insert it into the Event queue my time changes to 23:22 AM. For some reason it is adding 12 hours within the Event queue and I don't understand why.
Figured it out the totalMinutes() method was messing with the hours because it was being called when using compareTo() or timeDifference() implicitly. Thank you for the help!

First, totalMinutes() messes with the hour field when it shouldn't. It should use a local variable.
Second, your entire Event.compareTo(Event e) method can be reduced to
return e.eventTime.compareTo(eventTime);
which is back to front, unless you want the most recent times first. Try
return eventTime.compareTo(e.eventTime);