我正在尝试修改Relay类中的main方法，这样除了打印各种时间外，它还会打印它们的总和（所有3次的总和）。因为它们是一个字符串，我不知道数学可以在哪里完成。除此之外，我还尝试更改Relay类中的数组，以便它包含Time对象而不是TimeA对象。谢谢！
//Relay.java
public class Relay
{
public static void main(String[] args)
{
TimeA[] raceLegs = new TimeA[3];
raceLegs[0] = new TimeA(903);
raceLegs[1] = new TimeA(0,1,43);
raceLegs[2] = new TimeA(0,45,17);
System.out.println("First runner: " + raceLegs[0].toString());
System.out.println("Second runner: " + raceLegs[1].toString());
System.out.println("Third runner: " + raceLegs[2].toString());
//my clearly wrong attempt
System.out.println("The sum of all the runners is: " +
raceLegs[0].toString() + raceLegs[1].toString()+ raceLegs[2].toString());
}
}
//TimeATestToString.java
public class TimeATestToString {
@Test
public void testClassic() {
Time t = new TimeA(23,15,54);
assertEquals("23:15:54", t.toString());
}
@Test
public void testSingleDigits() {
Time t = new TimeA(1,2,3);
assertEquals("1:02:03", t.toString());
}
@Test
public void testZeros() {
Time t = new TimeA(1,3,0);
assertEquals("1:03:00", t.toString());
}
@Test
public void testZeros2() {
Time t = new TimeA(12,0,0);
assertEquals("12:00:00", t.toString());
}
}
//TimeA.java
public class TimeA implements Time
{
private int hours;
private int minutes;
private int seconds;
/**
* Simple constructor assumes data is in proper format
* @param h number of hours
* @param m number of minutes
* @param s number of seconds
*/
public TimeA(int h, int m, int s)
{
hours = h;
minutes = m;
seconds = s;
}
/**
* Return the number of leftover seconds (those not part of a full minute)
* in this object
* @return the number of seconds
*/
public int getSeconds()
{
return seconds;
}
/**
* Return the number of leftover minutes (those not part of a full hour)
* in this object
* @return the number of minutes
*/
public int getMinutes()
{
return minutes;
}
/**
* Return the number of full hours in this object
* @return the number of hours
*/
public int getHours()
{
return hours;
}
/**
* Constructor that assumes a total number of seconds
* @param total the total number of seconds taken
*/
public TimeA(int total)
{
hours = total/3600;
minutes = (total/60) % 60;
seconds = total % 60;
}
/**
* Adds the given time to the current time, producing the sum
* @param other the given time to add
* @return the sum of this time and the other time
*/
// public Time add (Time other)
// {
// return new TimeA(1,2,3);
// }
public Time add (Time other)
{
int remainder = 0;
int newSec = this.seconds + other.getSeconds();
// if over a minute, carry.
if (newSec >= 60) {
remainder = 1;
newSec -= 60;
}
this.seconds = newSec;
int newMin = this.minutes + remainder + other.getMinutes();
remainder = 0;
// carry if over an hour
if (newMin >= 60) {
remainder = 1;
newMin -= 60;
}
this.minutes = newMin;
this.hours += other.getHours() + remainder;
return this;
}
/**
* Return a String representation of this time
* @return this time represented as a String in hh:mm:ss format
*/
public String toString()
{
return String.format("%d:%02d:%02d", hours, minutes, seconds);
// return hours + ":" + minutes + ":" + seconds;
}
public int compareTo(Time other) {
return 17;
}
}
//TimeATestAdd.java
public class TimeATestAdd {
@Test
public void firstTest() {
Time t = new TimeA(0,44,19);
Time s = new TimeA(0,17,44);
Time u = s.add(t);
assertEquals("1:02:03", u.toString());
}
@Test
public void secondTest() {
Time t = new TimeA(4,19,21);
Time s = new TimeA(2,40,18);
Time u = s.add(t);
assertEquals("6:59:39", u.toString());
}
@Test
public void thirdTest() {
Time t = new TimeA(2,19,45);
Time s = new TimeA(2,40,5);
Time u = s.add(t);
assertEquals("4:59:50", u.toString());
}
@Test
public void fourthTest() {
Time t = new TimeA(9,12,15);
Time s = new TimeA(2,20,5);
Time u = s.add(t);
assertEquals("11:32:20", u.toString());
}
}
//Time.java
public interface Time extends Comparable<Time> {
/**
* Return the number of leftover seconds (those not part of a full minute)
* in this object
* @return the number of seconds
*/
public int getSeconds();
/**
* Return the number of leftover minutes (those not part of a full hour)
* in this object
* @return the number of minutes
*/
public int getMinutes();
/**
* Return the number of full hours in this object
* @return the number of hours
*/
public int getHours();
/**
* Return a String representation of this object in hh:mm:ss format
* @return this object as a String
*/
public String toString();
/**
* Add the given time record to this one
* @param other the time record to be added to this one
* @return the sum of this time record and the other
*/
public Time add(Time other);
}
答案 0 :(得分：1)
对象的toString()方法总是返回String，但显然你将整数放入TimeA的对象中，这样你就可以进行添加。不知道那个班级是什么样的，我最好的猜测是：
class TimeA implements Time {
private int hours;
private int minutes;
private int seconds;
public TimeA(int hours, int minutes, int seconds) {
this.hours = hours;
this.minutes = minutes;
this.seconds = seconds;
}
public void addTime(TimeA other) {
this.hours += other.hours;
this.minutes += other.minutes;
this.seconds += other.seconds;
}
}
那你怎么总结这些价值呢？没有编程你会怎么做？让我们说你有＆＃34; 5 + 7 + 9＆＃34;，你需要5，加7，然后是9，然后你就有了结果。这就是你现在想做的事情：
raceLegs[0].add( raceLegs[1] );
raceLegs[0].add( raceLegs[2] );
System.out.println("Sum: " + raceLegs[0].toString());
（我不确定你的意思＆＃34;我也试图更改Relay类中的数组，以便它保存Time对象＆＃34;，但它可能很容易将TimeA[] raceLegs = new TimeA[3]更改为Time[] raceLegs = new Time[3]。）