Java 同一数组中相同字符串名称的数目是否不超过？

我遇到的问题如下：我创建了10行输出，表示船只的停靠空间

但是码头可以容纳两种尺寸的船只；货物和集装箱。这些行由5个小行和5个中行组成。货船（小型）可停泊在任何可用空间。集装箱船（中型）可以停泊在中型空间，但不能停泊在小型空间

因此，如果我输入shipName和Container（例如），它将搜索数组，确保少于5个容器，以便它可以停靠，即保存在数组中。你能帮忙吗？ 以下是我的停靠方法：

import java.util.*;

public class Main {

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

public static void main(String[] args) {

        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");
                    printArray();
                    break;
                case 4:
                    System.out.println("4. Exit");
                    System.exit(0);
                default:
                    System.out.println("No such option");
                    break;
            }
        }
}

public static void dock() {

    int dockCapacity = 0;

    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:");
    //search for 5 small 3 med 2 large

 //    if what they entered equals shipSize more than 5 than cannot dock.
    for(int i = 1; i < dock1.length; i++) {
        if (dock1[i].getShipSize().equals(size)) {
            System.out.print(dock1[i].getShipSize());
        }
        else {
            System.out.println("Couldn't dock");
        }
    }
    //Check if the dock number is valid
    int i = Integer.valueOf(scan.nextLine());
    if (i >= 0 && i < 10 && dock1[i] == null){
        //Add ship to the dock
        dock1[i] = new Ship(name, size);
        System.out.println("Ship has been docked");
    }
    else{
        System.out.println("Couldn't dock");
    }
   // printArray();
}

public static void undock(){

    System.out.println("Status of ships: ");
    printArray();
    System.out.println("Enter ship's name to undock: ");
    String name = scan.nextLine();
    for(int i = 1; i < dock1.length; i++){
    if(dock1[i] != null && dock1[i].getShipName().equals(name)){
        dock1[i] = null;
        System.out.println("Ship removed");
        break;
    }
    else{
        System.out.println("Ship not docked here");
    }
    }

}

public static void printArray() {

    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());
        }
    }
}
}

---

我建议你像这样改变船型。它添加了一个ShipSize枚举，使得从字符串解析ShipSize和比较ShipSize更加容易。此外，我还添加了

isCargo

和

isContainer

方法

import java.util.Arrays;

public class Ship {

    private String shipName;
    private ShipSize shipSize;
    public Ship(String shipName, ShipSize shipSize) {
        this.shipName = shipName;
        this.shipSize = shipSize;
    }

    public String getShipName() {
        return shipName;
    }

    public void setShipName(String shipName) {
        this.shipName = shipName;
    }

    public ShipSize getShipSize() {
        return shipSize;
    }

    public void setShipSize(ShipSize shipSize) {
        this.shipSize = shipSize;
    }

    public boolean isCargo() {
        return shipSize == ShipSize.CARGO;
    }

    public boolean isContainer() {
        return shipSize == ShipSize.CONTAINER;
    }

    public enum ShipSize {
        CARGO,
        CONTAINER;

        public static ShipSize of(String size) {
            return Arrays.stream(ShipSize.values()).filter(enumSize -> enumSize.name().equalsIgnoreCase(size)).findAny().orElse(null);
        }
    }
}

我还修改了你的主类，所以它可以满足你的需要。我添加了一些解析和数字检查，为docks添加了一个初始化方法

import java.util.*;

public class Main {

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

    public static void main(String[] args) {

        initializeDock();

        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");
                    printArray();
                    break;
                case 4:
                    System.out.println("4. Exit");
                    System.exit(0);
                default:
                    System.out.println("No such option");
                    break;
            }
        }
    }

    private static void initializeDock() {
        for (int i = 0; i < 5; i++) {
            dock1[i] = new Dock(Ship.ShipSize.CARGO);
        }
        for (int i = 5; i < 10; i++) {
            dock1[i] = new Dock(Ship.ShipSize.CONTAINER);
        }
    }

    public static void dock() {

        int dockCapacity = 0;

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

        Ship.ShipSize size = null;
        while(size == null) {
            System.out.println("Enter ship's size: ");
            String stringSize = scan.nextLine();
            size = Ship.ShipSize.of(stringSize);
            if (size == null) {
                System.out.println("Could not read ship size. Only cargo and container are allowed.");
            }
        }

        // check that ship fits into any dock
        if (size == Ship.ShipSize.CONTAINER) {
            long numberOfContainerShips = Arrays.stream(dock1).map(Dock::getDockedShip).filter(Objects::nonNull).filter(Ship::isContainer).count();
            if (numberOfContainerShips >= 5) {
                System.out.println("No place for a ship that large. Aborting.");
                return;
            }
        }

        System.out.println("Enter the ships dock:");
        Integer dockNumber = null;
        while(dockNumber == null) {
            dockNumber = scan.nextInt();
            if (dockNumber < 0 || dockNumber > dock1.length - 1) {
                System.out.println("Illegal dock number. Only numbers between 0 and " + dock1.length + " are allowed.");
                dockNumber = null;
            }
        }

        Dock dock = dock1[dockNumber];
        if (dock.getDockedShip() != null) {
            System.out.println("Dock reserved - couldn't dock");
            return;
        }
        if (dock.getSupportedSize() == Ship.ShipSize.CARGO && size == Ship.ShipSize.CONTAINER) {
            System.out.println("Dock too small - couldn't dock");
            return;
        }

        dock.setDockedShip(new Ship(name, size));
    }

    public static void undock(){

        System.out.println("Status of ships: ");
        printArray();
        System.out.println("Enter ship's name to undock: ");
        String name = scan.nextLine();
        for(int i = 1; i < dock1.length; i++){
            if(dock1[i].getDockedShip() != null && dock1[i].getDockedShip().getShipName().equals(name)){
                dock1[i] = null;
                System.out.println("Ship removed");
                break;
            }
            else{
                System.out.println("Ship not docked here");
            }
        }

    }

    public static void printArray() {

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

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

---

首先，你能描述一下这个问题吗。什么不按预期工作？第二，你能给我们提供完整的代码吗？为了帮助您，我们需要查看Ship类，我们需要知道

dock1

变量是什么。@GeorgMuehlenberg问题是我不知道如何对其进行编码，因此当我输入shipSize时，它会检查输入的大小是否只有一定数量，然后可以保存到数组中。哇！谢谢你的深入回答，你帮了我很大的忙。我很感激，不客气。但代码中有一个小缺陷。在

undock（）

-方法中，需要

设置DockedShip（null）

。祝你进一步学习Java好运。

import java.util.*;

public class Main {

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

    public static void main(String[] args) {

        initializeDock();

        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");
                    printArray();
                    break;
                case 4:
                    System.out.println("4. Exit");
                    System.exit(0);
                default:
                    System.out.println("No such option");
                    break;
            }
        }
    }

    private static void initializeDock() {
        for (int i = 0; i < 5; i++) {
            dock1[i] = new Dock(Ship.ShipSize.CARGO);
        }
        for (int i = 5; i < 10; i++) {
            dock1[i] = new Dock(Ship.ShipSize.CONTAINER);
        }
    }

    public static void dock() {

        int dockCapacity = 0;

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

        Ship.ShipSize size = null;
        while(size == null) {
            System.out.println("Enter ship's size: ");
            String stringSize = scan.nextLine();
            size = Ship.ShipSize.of(stringSize);
            if (size == null) {
                System.out.println("Could not read ship size. Only cargo and container are allowed.");
            }
        }

        // check that ship fits into any dock
        if (size == Ship.ShipSize.CONTAINER) {
            long numberOfContainerShips = Arrays.stream(dock1).map(Dock::getDockedShip).filter(Objects::nonNull).filter(Ship::isContainer).count();
            if (numberOfContainerShips >= 5) {
                System.out.println("No place for a ship that large. Aborting.");
                return;
            }
        }

        System.out.println("Enter the ships dock:");
        Integer dockNumber = null;
        while(dockNumber == null) {
            dockNumber = scan.nextInt();
            if (dockNumber < 0 || dockNumber > dock1.length - 1) {
                System.out.println("Illegal dock number. Only numbers between 0 and " + dock1.length + " are allowed.");
                dockNumber = null;
            }
        }

        Dock dock = dock1[dockNumber];
        if (dock.getDockedShip() != null) {
            System.out.println("Dock reserved - couldn't dock");
            return;
        }
        if (dock.getSupportedSize() == Ship.ShipSize.CARGO && size == Ship.ShipSize.CONTAINER) {
            System.out.println("Dock too small - couldn't dock");
            return;
        }

        dock.setDockedShip(new Ship(name, size));
    }

    public static void undock(){

        System.out.println("Status of ships: ");
        printArray();
        System.out.println("Enter ship's name to undock: ");
        String name = scan.nextLine();
        for(int i = 1; i < dock1.length; i++){
            if(dock1[i].getDockedShip() != null && dock1[i].getDockedShip().getShipName().equals(name)){
                dock1[i] = null;
                System.out.println("Ship removed");
                break;
            }
            else{
                System.out.println("Ship not docked here");
            }
        }

    }

    public static void printArray() {

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

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

public class Dock {

    private Ship.ShipSize supportedSize;
    private Ship dockedShip = null;

    public Dock(Ship.ShipSize supportedSize) {
        this.supportedSize = supportedSize;
    }

    public Ship.ShipSize getSupportedSize() {
        return supportedSize;
    }

    public void setSupportedSize(Ship.ShipSize supportedSize) {
        this.supportedSize = supportedSize;
    }

    public Ship getDockedShip() {
        return dockedShip;
    }

    public void setDockedShip(Ship dockedShip) {
        this.dockedShip = dockedShip;
    }
}