求解Java作业 急求

Question 2.
We wish to model a digital clock, which records the time as 0:0:0 to 23:59:59. The clock,
which will be modelled by class DigitalClock, should have the following attributes:
hours (0 to 23)
minutes (0 to 59)
seconds (0 to 59)
which should all be declared as private, and the following methods:
DigitalClock() - creates a object and sets the time to 0:0:0
void setHours( int hrs ) – if hrs is not a valid value, sets the hours to 0
void setMinutes( int min ) – similar
void setSeconds( int sec ) – similar
void tick() – advances the clock one second
void displayTime( ) – to display the time.
String toString () – to display the time
Your jobs:
(1). Create the class DigitalClock.
(2). Create another class to test it. Design your test carefully to cover as many situations
as possible. Suggested testing:
a) set your clock to 23:59:50.
b) write a loop that calls the tick method 10 or more times printing the
current time after each tick. Check that the clock changes at midnight to
00:00:00
Note that we can’t really simulate a clock unless we use the Timer class to call the tick
method at intervals of one second – this is well beyond our current stage of learning.

DigitalClock 类

public class DigitalClock {

private int hours ;

private int minutes ;

private int seconds ;

public DigitalClock()//构造函数
{
this.hours=0;//初始化小时为0
this.minutes=0;//初始化分钟为0
this.seconds=0;//初始化秒针为0
}


// public int getHours() {
// return hours;
//}

public void setHours(int hours) {//判断小时大于等于0切小于等于23进行赋值否则设置为0
if(hours>=0&&hours<=23)
{
this.hours = hours;
}
else
{
this.hours =0;
}

}

// public int getMinutes() {
// return minutes;
// }

public void setMinutes(int minutes) {//判断分大于等于0切小于等于59进行赋值否则设置为0
if(minutes>=0&&minutes<=59)
{
this.minutes = minutes;
}
else
{
this.minutes =0;
}

}

// public int getSeconds() {
// return seconds;
// }

public void setSeconds(int seconds) {//判断秒大于等于0切小于等于59进行赋值否则设置为0
if(seconds>=0&&seconds<=59)
{
this.seconds = seconds;
}
else
{
this.seconds = 0;
}

}


public void tick()//让时间增加
{
this.seconds++;

if(this.seconds<=59)//当秒小于等于59秒是直接设置
{
this.setSeconds(this.seconds);
}
else//否则 分加一
{
this.minutes++;
this.setSeconds(this.seconds);
if(this.minutes<=59)//同上一样
{
this.setMinutes(this.minutes);
}
else//否则时 加一
{

this.hours++;
this.setMinutes(this.minutes);
this.setHours(this.hours);
}
}


}

public void displayTime()//没有返回类型的显示时间方法
{
System.out.println(""+this.hours+"-"+this.minutes+"-"+this.seconds);
}

public String toString()//返回字符串类型的方法
{
return ""+this.hours+"-"+this.minutes+"-"+this.seconds;
}
}

测试类

public class ceshi {

public static void main(String[] args) {
// TODO Auto-generated method stub

DigitalClock dis = new DigitalClock();
dis.setHours(23);
dis.setMinutes(59);
dis.setSeconds(50);

System.out.println("对时间为：23-59-50进行十次秒进结果是：");
for(int i=0;i<10;i++)
{
dis.tick();//推动时间增加
dis.displayTime();
}

}

}

测试结果