我有这个让我难过的家庭作业。我有一个24 小时制的时钟，它由两个 numberDisplay对象组成。 numberDisplay对象有一个限制器来控制它们，因此当分钟数达到 60 时，它会回滚到零并增加小时数。当小时数达到 24 时，它会回滚到零。
我的任务是将其从 24 小时制更改为 12 小时制，但我无法更改对象的任何内容。只有他们如何互动
到目前为止，我已经做到了：
private void updateDisplay()
{
int functionHours = Integer.parseInt(hours.getDisplayValue());
String amPM = "AM";
if ( functionHours == 0 ) {
hours.setValue(12);
amPM = "AM";
}
else if ( functionHours > 0 && functionHours < 12 )
{
hours.setValue(functionHours);
amPM = "AM";
}
else if ( functionHours == 12 ) {
hours.setValue(functionHours);
amPM = "PM";
}
else if ( functionHours > 12 && functionHours <= 23 ) {
functionHours -= 12;
hours.setValue(functionHours);
amPM ="PM";
}
displayString = hours.getDisplayValue() + ":" + minutes.getDisplayValue() + " " + amPM;
}
但是，当 hours.value 从 23 变回零时，时钟拒绝变回 AM。我很难过如何做到这一点。
NumberDisplay 对象：
/**
* The NumberDisplay class represents a digital number display that can hold
* values from zero to a given limit. The limit can be specified when creating
* the display. The values range from zero (inclusive) to limit-1. If used,
* for example, for the seconds on a digital clock, the limit would be 60,
* resulting in display values from 0 to 59. When incremented, the display
* automatically rolls over to zero when reaching the limit.
*
* @author Michael Kölling and David J. Barnes
* @version 2011.07.31
*/
public class NumberDisplay
{
private int limit;
private int value;
/**
* Constructor for objects of class NumberDisplay.
* Set the limit at which the display rolls over.
*/
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;
}
}
/**
* 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;
}
}