從構造函數中的另一個類調用非靜態方法

Question

我有一個汽車類，它的構造函數如下所示：

public Cars(String carID, String plateNum, String position, Attendant assignedTo, long currTime) {
        this.carID = carID;
        this.plateNum = plateNum;
        this.position = position;
        this.assignedTo = assignedTo;
        this.currTime = currTime;
    }

當我從菜單按創建汽車時，構造函數在另一個類（主）中初始化。

構造函數的參數全部由car類中的方法創建/啟動。 該系統應該是提供諸如（ID，位置和時間）之類的信息的系統。

問題是汽車對象尚未初始化，因此我無法使用這些方法。

但是我確實需要汽車對象包含其信息（例如汽車ID：CR1）。

該信息是除時間以外的所有字符串。

我怎樣才能做到這一點？

PS：我是編程新手。 起初我使用的是靜態方法，但事實證明靜態方法會給我的代碼帶來更大的麻煩。

我張貼了一些有我的靜態方法的內容，每個人都告訴我要刪除這些靜態方法。

public void addCar() {

    Cars car1 = new Cars(car1.getID(), car1.askCarID(), Cars.getPosition(), Attendant.askForAtt(), System.currentTimeMillis());
    myGarage.add(car1);
    if(!(car1.getAssignedTo()).equals(null)){
        car1.getAssignedTo().setAssign(car1);
        car1.getAssignedTo().setAvailable(false);
    }
}

當我要創建新車時，這就是所謂的。

我還把整個汽車課都放在了您需要的地方：

import java.util.ArrayList;
import java.util.Scanner;
import java.util.concurrent.TimeUnit;

import javax.swing.text.Position;

public class Cars {

    private String carID;
    private String plateNum;
    private String position;
    private 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;
        this.position = position;
        this.assignedTo = assignedTo;
        this.currTime = currTime;
    }

    public void createCarsID() {

        for (int x = 0; x < Garage.getCarsCapacity(); x++) {
            String tempCarID = ("CR" + (x + 1));
            tempArray2.add(tempCarID);
        }
    }

    public 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 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) {
        int hrs = (int) TimeUnit.MILLISECONDS.toHours(miliSeconds) % 24;
        int min = (int) TimeUnit.MILLISECONDS.toMinutes(miliSeconds) % 60;
        int sec = (int) TimeUnit.MILLISECONDS.toSeconds(miliSeconds) % 60;
        return String.format("%02d:%02d:%02d", hrs, min, sec);
    }

        @Override
        public String toString() {
            return "Car:" + plateNum + " ID:" + carID + " Position:" + position + " Assigned to:" + assignedTo.getId() 
            + "(" + assignedTo.getName() + ")" + " Parked at:" + convert(currTime);
        }
    }

Answer 1

我附上了可以幫助您的代碼：

首先，因為所有參數都可以是靜態變量，所以我將其移至構造函數。

第二，我移動靜態方法“ createCarsID（）;” 到一個靜態初始化塊，以避免不必要的調用。

該示例功能齊全。

package test;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.concurrent.TimeUnit;

import javax.swing.text.Position;

public class Cars {

private String carID;
private String plateNum;
private String position;
private Attendant assignedTo;
private long currTime;
static ArrayList<String> tempArray2 = new ArrayList<String>();

static{
    createCarsID();
}

public Cars() {
    this.carID = Cars.getID();
    this.plateNum = Cars.askCarID();
    this.position = Cars.generatePosition();
    this.assignedTo = Attendant.askForAtt();
    this.currTime = System.currentTimeMillis();
}

public static void createCarsID() {

    for (int x = 0; x < Garage.getCarsCapacity(); x++) {
        String tempCarID = ("CR" + (x + 1));
        tempArray2.add(tempCarID);
    }
}

public static String getID() {


    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 String generatePosition() {


    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));
            return getPos(tempPos);
            //tempArray2.get(x) = null;

        }
    }
    return null;
}

public static String getPos(String IdToPos) {
    String strPos = IdToPos.substring(2);
    int pos = Integer.parseInt(strPos);
    return  "GR" + pos;

}

public String getPlateNum() {
    return plateNum;
}


public String getCarID() {
    return carID;
}

public String getPosition() {
    return position;
}

public long getCurrTime() {
    return currTime;
}

public 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) {
    int hrs = (int) TimeUnit.MILLISECONDS.toHours(miliSeconds) % 24;
    int min = (int) TimeUnit.MILLISECONDS.toMinutes(miliSeconds) % 60;
    int sec = (int) TimeUnit.MILLISECONDS.toSeconds(miliSeconds) % 60;
    return String.format("%02d:%02d:%02d", hrs, min, sec);
}

    @Override
    public String toString() {
        return "Car:" + plateNum + " ID:" + carID + " Position:" + position + " Assigned to:" + assignedTo.getId() 
        + "(" + assignedTo.getName() + ")" + " Parked at:" + convert(currTime);
    }
}

最后為了調用這個函數：

package test;
public class main {
public static void main(String [] args){
    main test = new main();
    test.addCar();

}
public void addCar() {

    Cars car1 = new Cars();
    Garage myGarage = new Garage();
    myGarage.add(car1);
    if(!(car1.getAssignedTo()).equals(null)){
        car1.getAssignedTo().setAssign(car1);
        car1.getAssignedTo().setAvailable(false);
    }
}   
}