我有两节课。 Car和Attendant。
public Attendant(int staffNum, String id, boolean available, attNm name, Cars assign) {
this.staffNum = staffNum;
this.id = id;
this.available = available;
this.name = name;
this.assign = assign;
}
public Cars(String carID, String plateNum, String position, Attendant assignedTo, long currTime) {
this.carID = carID;
this.plateNum = plateNum;
Cars.position = position;
Cars.assignedTo = assignedTo;
this.currTime = currTime;
}
我的获奖者是用for循环创建的：
createIDList();
int staffAmount = getStaffAmount();
for (int x = 0; x < staffAmount; x++) {
Attendant att = new Attendant(x + 1, Attendant.tempArray[x], true, attNm.getNm(), null);
myAtt.add(att);
}
for (int x = 0; x < myAtt.size(); x++) {
System.out.println(myAtt.get(x));
}
所有参数都来自一个从ArrayList获取它们的函数。所有服务员都有相同的名字。
汽车也一样。 每次我创造一辆汽车，它都来自一个功能，汽车将有他们的名字：汽车
当他们被创建时，我的服务员和我的车被加入他们的ArrayList（ArraylistCar和arraylistAtt）
但是当我创造新车时，所有车辆都输出相同的ID，并且错误地输出了服务员的详细信息。
有人告诉我静态方法和变量是这个问题的原因。所以我试图删除一些静态但我得到错误。 如果我使用getID方法删除静态，我无法在话务员类中调用它。 当我使用方法作为参数创建一个新类时，这些情况也会发生（方法不再是静态的，所以我不能从另一个类中调用它们。）
请帮助我，我被困住了。我知道很久我尝试了不同的方法，但没有任何效果。
我也提出了toString()方法，以防它们出现问题。
有些人告诉我也要把我的整个代码和输出，所以如果你需要的话，它完全在下面。
车：
@Override
public String toString() {
return "Car:" + plateNum + " ID:" + carID + " Position:" + position + " Assigned to:" + assignedTo.getId()
+ "(" + assignedTo.getName() + ")" + " Parked at:" + convert(currTime);
}
Attandant：
@Override
public String toString() {
return "Attendant [staffNum=" + staffNum + ", id=" + id + ", available=" + available + ", name=" + name
+ ", Car=" + assign + "]";
}
PS：英语不是我的母语。
我的整个代码在这里：
public class Cars {
private static String carID;
private String plateNum;
private static String position;
private static Attendant assignedTo;
private long currTime;
static ArrayList<String> tempArray2 = new ArrayList<String>();
public Cars(String carID, String plateNum, String position, Attendant assignedTo, long currTime) {
this.carID = carID;
this.plateNum = plateNum;
Cars.position = position;
Cars.assignedTo = assignedTo;
this.currTime = currTime;
}
private static void createCarsID() {
for (int x = 0; x < Garage.getCarsCapacity(); x++) {
String tempCarID = ("CR" + (x + 1));
tempArray2.add(tempCarID);
}
}
public static String getID() {
createCarsID();
String tempID = null;
String tempPos = null;
for (int x = 0; x < Garage.getCarsCapacity(); x++) {
if (tempArray2.get(x) != null) {
tempID = tempArray2.get(x);
tempPos = tempArray2.get(x);
tempArray2.remove(tempArray2.get(x));
getPos(tempPos);
//tempArray2.get(x) = null;
break;
}
}
return tempID;
}
public static void getPos(String IdToPos) {
String strPos = IdToPos.substring(2);
int pos = Integer.parseInt(strPos);
position = "GR" + pos;
}
public String getPlateNum() {
return plateNum;
}
public static String getCarID() {
return carID;
}
public static String getPosition() {
return position;
}
public long getCurrTime() {
return currTime;
}
public static Attendant getAssignedTo() {
return assignedTo;
}
public static String askCarID() {
boolean valid = false;
System.out.println("Please enter your car's plate number.");
Scanner scanCarID = new Scanner(System.in);
String scannedCarID = scanCarID.nextLine();
while (!valid) {
if (scannedCarID.matches("^[A-Za-z][A-Za-z] [0-9][0-9][0-9]$")) {
valid = true;
System.out.println(scannedCarID);
} else {
System.out.println("Please enter a valid plate number. Ex: AF 378");
askCarID();
}
}
return scannedCarID.toUpperCase();
}
public String convert(long miliSeconds) {
...
}
@Override
public String toString() {
return "Car:" + plateNum + " ID:" + carID + " Position:" + position + " Assigned to:" + assignedTo.getId()
+ "(" + assignedTo.getName() + ")" + " Parked at:" + convert(currTime);
}
}
public class Attendant {
private static int staffAmount = 10;
public int staffNum;
private String id;
private boolean available;
private attNm name;
private Cars assign;
private String user;
static String[] tempArray = new String[staffAmount];
static ArrayList<Attendant> myAtt = new ArrayList<Attendant>();
public Attendant(int staffNum, String id, boolean available, attNm name, Cars assign) {
this.staffNum = staffNum;
this.id = id;
this.available = available;
this.name = name;
this.assign = assign;
}
public Attendant(String user) {
this.user = user;
}
public static void createAtt() {
createIDList();
int staffAmount = getStaffAmount();
Attendant att = null;
for (int x = 0; x < staffAmount; x++) {
att = new Attendant(x + 1, Attendant.tempArray[x], true, attNm.getNm(), null);
myAtt.add(att);
}
for (int x = 0; x < myAtt.size(); x++) {
System.out.println(myAtt.get(x));
}
}
public static void startWork() {
createAtt();
}
public static Attendant askForAtt() {
Scanner scanAtt = new Scanner(System.in);
Random randAtt = new Random();
//Attendant asnAtt = null;
System.out.println("Do you require an Attendant ? Y or N");
String response = scanAtt.next();
if ((response.equals("y")) || (response.equals("yes")) || (response.equals("Yes")) || (response.equals("Y"))) {
// Cars.setAssignedTo(myAtt.get(randAtt.nextInt(myAtt.size())));
Attendant attendant = myAtt.get(randAtt.nextInt(myAtt.size()));
while(!attendant.isAvailable()){
attendant = myAtt.get(randAtt.nextInt(myAtt.size()));
}
return attendant;
} else if ((response.equals("n")) || (response.equals("no")) || (response.equals("No")) || (response.equals("N"))) {
return new Attendant ("User");
}
return new Attendant ("User"); //If input is neither Yes nor No then return new Attendant
}
public static void assignCarAtt(){
}
public int getStaffNum() {
return staffNum;
}
public static int getStaffAmount() {
return staffAmount;
}
public void setStaffNum(int staffNum) {
this.staffNum = staffNum;
}
public void setAvailable(boolean available) {
this.available = available;
}
public boolean getAvailable(){
return available;
}
public void setAssign(Cars assign) {
this.assign = assign;
}
public String getId() {
return id;
}
public boolean isAvailable() {
return available;
}
public attNm getName() {
return name;
}
public static void createIDList() {
for (int x = 0; x < staffAmount; x++) {
tempArray[x] = ("Att" + (x + 1));
}
}
public String strAssignAttCar(Cars assign){
String result = null;
if(assign!=null){
result = Cars.getCarID();
}
return result;
}
@Override
public String toString() {
return "Attendant [staffNum=" + staffNum + ", id=" + id + ", available=" + available + ", name=" + name
+ ", Car=" + assign + "]";
}
}
车库类打印;
Car:HU 457 ID:CR2 Position:GR2 Assigned to:Att10(Ava) Parked at:18:32:08, Car:HU 457 ID:CR2 Position:GR2 Assigned to:Att9(Elizabeth) Parked at:18:32:21]
// Should have been like that:
Car:HU 457 ID:CR1 Position:GR1 Assigned to:Att10(Ava) Parked at:18:32:08, Car:HU 457 ID:CR2 Position:GR2 Assigned to:Att9(Elizabeth) Parked at:18:32:21]
服务员班级打印;
Attendant [staffNum=9, id=Att9, available=false, name=Elizabeth, Car=Car:HU 457 ID:CR2 Position:GR2 Assigned to:Att9(Elizabeth) Parked at:18:32:21]
Attendant [staffNum=10, id=Att10, available=false, name=Ava, Car=Car:HU 457 ID:CR2 Position:GR2 Assigned to:Att10(Ava) Parked at:18:32:08]
// Should have been like that:
Attendant [staffNum=9, id=Att9, available=false, name=Elizabeth, Car=Car:HU 457 ID:CR2 Position:GR2 Assigned to:Att9(Elizabeth) Parked at:18:32:21]
Attendant [staffNum=10, id=Att10, available=false, name=Ava, Car=Car:HU 457 ID:CR1 Position:GR1 Assigned to:Att10(Ava) Parked at:18:32:08]
答案 0 :(得分：2)
首先，让Cars类单数化，即Car更有意义。
背景信息：在语句Cars car1 = new Cars()中，Cars是类，car1是Cars类的实例。这个问题是由混淆两个引起的。
静态变量/方法与类的任何特定实例无关;它只与班级相关联。因此，当您将carID声明为static时，您说只有一个全局Cars.carID，而不是许多car1.carID，car2.carID等。确保实例变量/方法不是静态的。
删除static关键字时遇到的问题是因为您拨打的是Cars.getCarID()而不是car1.getCarID()。您需要将类上的所有方法调用更改为类的实例上的方法调用。
tl; dr：要解决此问题，请删除所有static个关键字，并将对Cars.getCarID()等方法的所有静态引用更改为car1.getCarID()。
面向对象编程的示例（注意除了main方法之外没有静态方法或变量）：
Car.java：
class Car {
int id;
int speed;
Car(int id, int speed) {
this.id = id;
this.speed = speed;
}
int getSpeed() {
return speed;
}
void setSpeed(int newSpeed) {
speed = newSpeed;
}
int getId() {
return id;
}
void goFast() {
System.out.println("VROOM! This car is going so fast: " + speed);
}
}
Person.java：
class Person {
Car myCar;
int id;
Person(int id, Car car) {
this.id = id;
this.myCar = car;
}
int getCar() {
return myCar;
}
int getId() {
return id;
}
void floorIt() {
myCar.setSpeed(myCar.getSpeed() + 10);
void drive() {
myCar.goFast();
}
}
Main.java：
class Main {
public static void main(String[] args) {
Car ferrari = new Car(1, 1000);
Car bmw = new Car(2, 500);
Person alice = new Person(1, ferrari);
Person bobby = new Person(2, bmw);
alice.drive();
bobby.drive();
bobby.floorIt();
bobby.drive();
}
}