【发布时间】：2020-05-07 13:49:41
【问题描述】：
我正在尝试编写一个名为 RailwayStation 的类，它将打印一个火车数组（使用我编写的两个不同的类，称为 TIME1 和 Train。我的问题是我不明白为什么输出排列顺序不对。
我认为问题出在名为 addTrain 的类中的方法中，如果数组中存在空单元格，并且如果希望添加的行程不存在，则该方法应该添加火车行程数组。我使用的另一种方法（可能是问题所在）称为removeTrain，它接收火车行程的参数并将其从数组中删除。我的方法addTrain、removerTrain、toString如下：
public class RailwayStation {
// declrations of final variables
private final int MAX_TRAINS = 100;
private final int MIN_VAL = 0;
// declrations of instant variables
private Train[] _station;
private int _noOfTrs;
/**
* Empty construter which initialize the instant variables of the class such that the trips array will be in a maximal size
*/
public RailwayStation() {
_station = new Train[MAX_TRAINS];
_noOfTrs = MIN_VAL;
}
/**
* adds a train trip to the trips array
*
* @param f the train trip
* @Returns true if a train trip has been added to the trips array
*/
public boolean addTrain(Train f) {
int i, j;
// boolean found = false;
if (isTrainOnSomeStation(f)) {
return false;
}
else {
for (j = MIN_VAL; j < _station.length; j++) {
if (_station[j] == null) {
_station[j] = f;
_noOfTrs++;
return true;
}
}
return false;
}
}
// a private method that checks if @param f is null
private boolean isTrainOnSomeStation(Train f) {
if (f == null) {
return false;
}
for (int i = MIN_VAL; i < _station.length; i++) {
if (_station[i] != null && _station[i].equals(f)) {
return true;
}
}
return false;
}
/**
* removes a trip from the trips array
* @param f the train trip
* @returns true if the train trip has been removed
*/
public boolean removeTrain(Train f) {
int i, j;
boolean found = false;
for (j = MIN_VAL; j < _station.length && !found; j++) {
if (_station[j] != null) {
for (i = MIN_VAL; i < _noOfTrs && !found; i++)
if (_station[i].equals(f)) {
_station[i] = _station[_noOfTrs];
_station[_noOfTrs] = null;
found = true;
_noOfTrs--;
}
}
}
return found;
}
/** Returns a string which describes all train in the array as apperas in the arrray
* @Returns a string of trains as appears in the arrat
*/
public String toString(){
String str = "The trains today are:" +"\n";
if(_noOfTrs == MIN_VAL){
return "There are no trains today.";
}
else {
String capacity = "";
for (int i = 0; i < _station.length; i++) {
if (_station[i] != null) {
if (_station[i].isFull() == true) {
capacity = "Train is full";
}
else {
capacity = "Train is not full";
}
str += _station[i].toString() + "\n";
}
}
}
return str;
}
}
为了调用 addTrain 方法，我会写：
//Check constructor
RailwayStation rs = new RailwayStation();
//AddTrain
Train f1 = new Train("Haifa",12,0,210,250,250,55);
Train f2 = new Train("Jerusalem",10,50,210,250,250,40);
rs.addTrain(f1);
rs.addTrain(f2);
System.out.println(rs);
//RemoveTrain
rs.removeTrain(f1);
System.out.println(rs);
//First Train to Destination
Train f3 = new Train("Tel-Aviv",11,35,180,100,200,35);
rs.addTrain(f3);
Train f3a = new Train("Tel-Aviv",7,15,180,200,200,35);
rs.addTrain(f3a);
我期待得到输出：
The trains today are:
Train to Jerusalem departs at 10:50. Train is full.
Train to Tel-Aviv departs at 11:35. Train is not full.
Train to Tel-Aviv departs at 07:15. Train is full.
但我得到的是：
The trains today are:
Train to Tel-Aviv departs at 11:35. Train is not full.
Train to Jerusalem departs at 10:50. Train is full.
Train to Tel-Aviv departs at 07:15. Train is full.
我尝试使用调试器来了解顺序出错的部分，但我找不到问题所在。
【问题讨论】：
-
你怎么打电话给
addTrain？请提供完整的minimal reproducible example -
@UnholySheep 已修复
-
@Jneven 你的 addTrain 调用似乎与打印不匹配？
-
@LarsNielsen - 对不起，你是对的，我已经解决了