我的测试类有问题，如您在下面看到的输出，分钟返回一个我不希望出现的附加“ 0”，我相信问题出在我的NumberDisplay类中的getDisplayValue方法。在我尝试如果情况不正确的情况下，但是它给了我很多“ 0”，然后我的老师建议我对情况进行处理，所以我做到了，结果在我的测试班级比NumberDisplay要好。我在第2个测试类中尝试进行计时，这似乎很奇怪，如果您知道问题出在哪里，我将不胜感激
public class NumberDisplay {
private int minLimit;
private int maxLimit;
private int value;
private boolean wrapped;
public NumberDisplay(int minLimit, int maxLimit) throws IllegalValueException {
if (maxLimit > minLimit) {
this.minLimit = minLimit;
this.maxLimit = maxLimit - 1;
this.value = minLimit;
this.wrapped = true;
// creates new number display with the value minimum limit
// and the limits between maximum limit. if maximum limit is not greater than
// minimum limit
// it should throw exception
} else {
throw new IllegalValueException("felaktig");
}
}
public int getValue() {
return this.value;
// return the current value on display with integer number
}
public void setValue(int newValue) throws IllegalValueException {
if (newValue < minLimit || newValue >= maxLimit) {
throw new IllegalValueException("Felaktig prova igen set time är felaktig");
// set the current display value to newValue. if newValue is less greater than
// minimum limit
// or greater than value from display then throw exception
} else {
this.value = newValue;
}
}
public String getDisplayValue() {
String str = String.valueOf(this.maxLimit);
String str1 = "0";
if(str.length()==1) {
return str1+this.value;
}
if(str.length()==2) {
return str1+this.value;
}
if(str.length()==3) {
return str1+str1+this.value;
}
if(str.length()==4) {
return str1+str1+str1+this.value;
}
if(str.length()==5) {
return str1+str1+str1+str1+this.value;
}
if(str.length()==6) {
return str1+str1+str1+str1+str1+this.value;
}else {
for(int i =0;i<str.length();i++) {
str1 = str1 +this.value;
}
}
return ""+this.value;
}
// return the current value with 0 infront of the value
public void increment() {
if (this.value == maxLimit) {
this.value = this.minLimit;
this.wrapped = true;
} else {
this.value = +1;
}
// increases the display with one value and checks if maximum limit is reached
// then
// it should be converted to minimum limit
// Consider to do the string delightful so all of values sets with as many as
// numbers
// the display should have. Values with low numbers should be zeros in front,
// e.g. clock 9 09:00
}
public boolean diWrapAround() {
if (this.value < maxLimit) {
return this.wrapped = true;
} else
return false;
}
// it should return true if the display reached over maximum limit and started
// from
// minimum limit , otherwise it should return false,
// use attribute wrapped to check boolean false or true.
}
public class Clock {
private NumberDisplay hours;
private NumberDisplay minutes;
private String displayString;
public Clock() throws IllegalValueException {
this.hours = new NumberDisplay(0, 24);
this.minutes = new NumberDisplay(0, 60);
this.updateDisplay();
}
public Clock(int hour, int minute) throws IllegalValueException {
this.hours = new NumberDisplay(0, 24);
this.minutes = new NumberDisplay(0, 60);
this.hours.setValue(hour);
this.minutes.setValue(minute);
this.updateDisplay();
}
public void timeTick() {
this.minutes.increment();
}
public void setTime(int hour, int minute) throws IllegalValueException {
this.hours.setValue(hour);
this.minutes.setValue(minute);
this.updateDisplay();
}
public String getTime() {
return this.displayString;
}
private void updateDisplay() {
this.displayString = this.hours.getDisplayValue()+":"+this.minutes.getDisplayValue();
}
}
public class Test2 {
public static void main(String[] args) {
try {
Clock klocka = new Clock(4343, 223);
System.out.println(klocka.getTime());
} catch (IllegalValueException a) {
System.out.println(a.getMessage());
}
System.out.println("Expected: felmeddelande");
System.out.println("");
try {
Clock klocka = new Clock(0, 24);
System.out.println(klocka.getTime());
System.out.println("Expected: 00:24");
System.out.println("");
klocka.timeTick();
System.out.println(klocka.getTime());
System.out.println("Expected: 00:01");
System.out.println("");
System.out.println(klocka.getTime());
System.out.println("Expected to be 00:00");
System.out.println("");
try {
klocka.setTime(123, 4554);
System.out.println(klocka.getTime());
} catch (IllegalValueException a) {
System.out.println(a.getMessage());
}
System.out.println("Expected: Felmeddelande");
System.out.println("");
try {
klocka.setTime(12, 23);
System.out.println(klocka.getTime());
} catch (IllegalValueException e) {
System.out.println(e.getMessage());
}
System.out.println("Expected: 12:23");
System.out.println("");
} catch (IllegalValueException a) {
System.out.println(a.getMessage());
}
}
}
输出
Felaktig prova igen set time är felaktig
Expected: felmeddelande
00:024
Expected: 00:24
00:024
Expected: 00:01
00:024
Expected to be 00:00
Felaktig prova igen set time är felaktig
Expected: Felmeddelande
012:023
Expected: 12:23
答案 0 :(得分：1)
问题在于var strDate = new Date(); // By default Date empty constructor give you Date.now
var shortYear = strDate.getFullYear();
// Add this line
var twoDigitYear = shortYear.toString().substr(-2);
并没有考虑getDisplayValue本身的长度，而是完全根据value来做出决策。参见：
maxLimit对于两位数显示，它将用零填充任何if(str.length()==2) {
return str1+this.value;
}
。因此，对于“ 0”，您将获得“ 00”；对于“ 12”，您将获得“ 012”。
要解决此问题，您需要考虑value的长度：
value如果要避免循环，有更聪明的方法用零填充字符串。参见：Left padding a String with Zeros
P.S。在测试int limit = String.valueOf(maxLimit).length();
int length = String.valueOf(value).length();
StringBuilder displayValue = new StringBuilder();
//add a necessary number of zeros
for(int i=0; i<limit-length; i++) {
displayValue.append("0");
}
displayValue.append(value);
return displayValue.toString();
之前，您可能应该单独测试NumberDisplay。