I am working specifically with java on BlueJ. I was given code for a 24-hour clock (00:00-23:59) and was tasked with changing it to a 12-hour clock with "am" or "pm" displayed next to the time. I am using the method of having the clock function internally as a 24-hour clock, but having the display string show the 12 hour version (ie: showing 4:30pm instead of 16:30). I am very close but I am running into two problems: 1. When the clock goes up from 11:59pm it displays 12:00pm rather than 12:00am; 2.When "0" is entered for hours, I want it to show "12".

The code I have so far is included below

Thank you in advance!

For ClockDisplay Class:

public class ClockDisplay
{
private NumberDisplay hours;
private NumberDisplay minutes;
private String displayString; // simulates the actual display

/**
* Constructor for ClockDisplay objects. This constructor
* creates a new clock set at 00:00.
*/
public ClockDisplay()
{
hours = new NumberDisplay(24);
minutes = new NumberDisplay(60);
updateDisplay();
}

/**
* Constructor for ClockDisplay objects. This constructor
* creates a new clock set at the time specified by the
* parameters.
*/
public ClockDisplay(int hour, int minute)
{
hours = new NumberDisplay(24);
minutes = new NumberDisplay(60);
setTime(hour, minute);
}

/**
* This method should get called once every minute - it makes
* the clock display go one minute forward.
*/
public void timeTick()
{
minutes. increment();
if(minutes. getValue() == 0)
{ // it just rolled over!
hours. increment();
}
updateDisplay();
}

/**
* Set the time of the display to the specified hour and
* minute.
*/
public void setTime(int hour, int minute)
{
hours. setValue(hour);
minutes. setValue(minute);
updateDisplay();
}

/**
* Return the current time of this display in the format HH:MM.
*/
public String getTime()
{
return displayString;
}
/**
* Update the internal string that represents the display.
*/
private void updateDisplay()
{
String pmam = ampm(hours. getValue());
displayString = hours. twelveHour() + ":" +
minutes. getDisplayValue()+" "+pmam;
}

private String ampm(int value)
{
if((value < 12) || (value == 24) || (value == 0))
{
return "am";
}
else
{
return "pm";
}
}
}

For the NumberDisplay Class:

public class NumberDisplay
{
private int limit;
private int value;

/**
* Constructor for objects of class Display
*/
public NumberDisplay(int rollOverLimit)
{
limit = rollOverLimit;
value = 0;
}

/**
* Return the current value.
*/
public int getValue()
{
return value;
}

/**
* Return the display value (that is, the current value as a two-digit
* String. If the value is less than ten, it will be padded with a leading
* zero).
*/
public String getDisplayValue()
{
if(value < 10)
{
return "0" + value;
}
else
{
return "" + value;
}
}

public String twelveHour()
{
if(value < 10)
{
return "0" + value;
}
else if(value > 12)
{
value = value - 12;
return "" + value;
}
else if(value == 0)
{
return "12";
}
else
{
return "" + value;
}
}
/**
* Set the value of the display to the new specified value. If the new
* value is less than zero or over the limit, do nothing.
*/
public void setValue(int replacementValue)
{
if((replacementValue >= 0) && (replacementValue < limit))
{
value = replacementValue;
}
}
/**
* Increment the display value by one, rolling over to zero if the
* limit is reached.
*/
public void increment()
{
value = (value + 1) % limit;
}
}