java - 两个问题。不添加到数组中的下一个索引，也不从数组中删除

Question

我遇到的问题如下:我创建了两个代表船舶停靠空间的数组。第一个数组将船舶对象(shipName 和大小 - 通常是 super 容器)保存在数组中，如果没有空间，则将其添加到等待列表数组中。如果第一个数组中的空间空闲，则等待列表中的船舶将加入第一个数组。

但是当我去停靠(从第一个数组中删除一艘船)时，它只在第一个数组的索引 0 中找到该船，而不是索引 1、2 等。

此外，我只能将一艘船添加到等待名单中，但它显示已满。 你能帮我吗？这是我的停靠类，undock() 和 waitingList() 中的问题:

import java.util.*;

public class Main {

static Scanner scan = new Scanner(System.in);
private static Ship[] dock1 = new Ship[10];
private static Ship[] waitingList = new Ship[10];

public static void main(String[] args) {
    menu();
}

public static void menu() {


    Scanner scan = new Scanner(System.in);


    while (true) {

        System.out.println("Choose an option: 1-3");
        System.out.println("1. Dock");
        System.out.println("2. Undock");
        System.out.println("3. Status");

        int menu = scan.nextInt();
        switch (menu) {
            case 1:
                System.out.println("1. Dock");
                dock();
                break;
            case 2:
                System.out.println("2. Undock");
                undock();
                break;
            case 3:
                System.out.println("3. Status");
                printDock();
                printWaitingList();
                break;
            case 4:
                System.out.println("4. Exit");
                System.exit(0);
            default:
                System.out.println("No such option");
                break;
        }
    }
}


public static void dock() {

    System.out.println("Enter ship's name: ");
    String name = scan.nextLine();

    System.out.println("Enter ship's size: ");
    String size = scan.nextLine();

    System.out.println("Enter the ships dock:");
    //Check if the dock number is valid
    int i = Integer.valueOf(scan.nextLine());
    if (i >= 0 && i < 10 && dock1[i] == null) {
        int c = 0;
        int co = 0;
        int sco = 0;
        for (int j = 0; j < dock1.length; j++) {
            if (dock1[j] != null &&         dock1[j].getShipSize().equals("Cargo")) {
                c++;
            }
            if (dock1[j] != null && dock1[j].getShipSize().equals("Container")) {
                co++;
            }
            if (dock1[j] != null && dock1[j].getShipSize().equals("Super-Container")) {
                sco++;
            }
        }

        if (c < 10 && co < 5 && sco < 2) {
            //Add ship to the dock
            dock1[i] = new Ship(name, size);
            System.out.println("Enough space you can dock");
            System.out.println("Ship has been docked");
        } else {
            System.out.println("You cannot dock");
            waitingList(name,size);
        }

    } else {
        System.out.println("Couldn't dock");
        waitingList(name, size);
    }

}


public static void undock() {
    System.out.println("Status of ships: ");
    printDock();
    System.out.println("Enter ship's name to undock: ");
    String name = scan.nextLine();
    //System.out.println("Enter ship's size to undock: ");
   // String size = scan.nextLine();

    for (int i = 0; i < dock1.length; i++) {
        if (dock1[i] != null && dock1[i].getShipName().equals(name)) {
            dock1[i] = null;
            System.out.println("Ship removed");
            /// HERE CHECK IF SHIP IN DOCK
            for (int j = 0; j < waitingList.length; j++) {
                if (dock1[i] == null) {
                    // Add ship to the dock
                    dock1[i] = new Ship(waitingList[j].getShipName(), waitingList[j].getShipSize());
                    System.out.println("Move ship from waiting list to dock 1");
                    waitingList[j] = null;
                   break;
                } else {
                    System.out.println("No space in dock1");
                    return;
                }
            }
        } else {
            System.out.println("Ship not docked here");
            break;
        }

    }

}

public static void waitingList(String name, String size){
    System.out.println("Dock 1 is full, ship will try to be added to Waiting List");
    for (int i = 0; i < waitingList.length; i++) {
        if (waitingList[i] == null) { //CHANGE TO ALLOW MORE THAN ONE SHIP
            //Add ship to the dock
            waitingList[i] = new Ship(name, size);
            System.out.println("Enough space added to waiting list");
            break;
        } else {
            System.out.println("No space on waiting list, ship turned away");
            return;
        }
    }

}


public static void printDock() {

    System.out.println("Docks:");

    for (int i = 0; i < dock1.length; i++) {
        if (dock1[i] == null) {
            System.out.println("Dock " + i + " is empty");
        } else {
            System.out.println("Dock " + i + ": " + dock1[i].getShipName() + " " + dock1[i].getShipSize());
        }
    }
}

private static void printWaitingList() {

    System.out.println("Waiting List:");

    for (int i = 0; i < waitingList.length; i++) {
        if (waitingList[i] == null) {
            System.out.println("Dock " + i + " is empty");
        } else {
            System.out.println("Dock " + i + ": " + waitingList[i].getShipName() + " " + waitingList[i].getShipSize());
        }
    }
}
}

Answer 1

您的循环仅适用于数组的第一个元素，因为当检查失败时(例如 waitingList 中的 if (waitingList[i] == null))，您打印错误，然后返回，从而打破循环。您需要做的是使 boolean dockSuccessful = false，然后如果满足条件(dock 中有空间)，则将其设置为 true，然后 break 循环(这样你就不会多次停靠船舶)。在您插入的循环之后

if(!dockSuccessful) {
    System.out.println("Some error message here");
}

因此，如果循环找到至少一个空停靠点，dockSuccessful 将为 true，并且不会打印错误。但如果它检查了所有 jetty ，它不会更新dockSuccessful，它仍然是false，并且会打印错误。