在嵌套的for循环内，打印字符串“。”，如果满足条件，则将其替换为其他字符。 MOOC Java第10周“地牢”

Question

I'm working on this project MOOC Java Week 10 Exercise 33

I want String . replaced by player/vampire symbol (String @ and v ), when the player/vampire position X and Y are equal to X and Y of Grid. (Height and Width of Grid are printed by string . ). The problem is in Class Dungeon , method printMap() .

Class Player

public class Player {

private final String symbol;
private int posX, posY, width, height;

public Player(String symbol, int width, int height) {
    this.symbol = symbol;
    this.posX = 0;
    this.posY = 0;
    this.width = width - 1;
    this.height = height - 1;
}

public String getSymbol() {

    return symbol;
}

public int getPosX() {

    return posX;

}

public int getPosY() {

    return posY;

}

public void setPosX(int x) {

    posY = x;

}

public void setPosY(int y) {

    posY = y;
}

public String getPos() {

    return posX + " " + posY;
}

public void keyMap(String keyPressed) {
    boolean y = posY > 0;
    boolean h = posY < height;
    boolean x = posX > 0;
    boolean w = posX < width;

    if (keyPressed.equalsIgnoreCase("w")) {
        if (y) {
            posY--;
        }
    } else if (keyPressed.equalsIgnoreCase("s")) {
        if (h) {
            posY++;
        }
    } else if (keyPressed.equalsIgnoreCase("a")) {
        if (x) {
            posX--;
        }
    } else if (keyPressed.equalsIgnoreCase("d")) {
        if (w) {
            posX++;
        }
    }

}

@Override
public String toString() {

    return symbol + " " + posX + " " + posY;
}

}

Class Vampire

package dungeon;

import java.util.Random;


public class Vampire {

    private String symbol;
    private int posX, posY, width, height;
    private final Random rand = new Random();

public Vampire(String symbol, int width, int height) {
    this.symbol = symbol;
    this.posX = rand.nextInt(width);
    this.posY = rand.nextInt(height);
    this.width = width - 1;
    this.height = height - 1;

}

public String getSymbol() {

    return symbol;
}

public int getPosX() {

    return posX;

}

public int getPosY() {

    return posY;

}

public String getPos() {

    return posX + " " + posY;
}

public void setPosX(int x) {

    posX = x;

}

public void setPosY(int y) {

    posY = y;
}

public void resetPos() {
    posX = rand.nextInt(width);
    posY = rand.nextInt(height);
    checkStartPos();
}

public void checkStartPos() {

    while (posX == 0 || posY == 0) {
        if (posX == 0) {
            posX = rand.nextInt(width);
        } else if (posY == 0) {
            posY = rand.nextInt(height);
        }
    }

}

public void move() {
    boolean y = posY > 0;
    boolean h = posY < height;
    boolean x = posX > 0;
    boolean w = posX < width;

    int direction = rand.nextInt(4);
    switch (direction) {
        case 0:
            if (y) {
                posY--;
                break;
            }
        case 1:
            if (h) {
                posY++;
                break;
            }
        case 2:
            if (x) {
                posX--;
                break;
            }
        case 3:
            if (w) {
                posX++;
                break;

            }

    }
}

@Override
public String toString() {

    return symbol + " " + posX + " " + posY;
}

}

Class Dungeon

package dungeon;

import java.util.ArrayList;
import java.util.List;

public class Dungeon {

private Player player;
private List<Vampire> vampires = new ArrayList<Vampire>();
private int width;
private int height;
private int BP; // lamp battery point
private boolean canVampireMove;

public Dungeon(int width, int height, int vampires, int moves, boolean vampiresMove) {

    this.player = new Player("@", width, height);
    this.width = width;
    this.height = height;
    this.BP = moves;
    this.canVampireMove = vampiresMove;

    for (int i = 0; i < vampires; i++) {
        this.vampires.add(new Vampire("v", width, height));
    }

}


public void printCoordinate() {
    System.out.println(BP);
    System.out.println("\n" + player);
    for (Vampire each : vampires) {
        System.out.println(each);
    }
}

public void printMap() {

    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {


                if (player.getPos().equals(x + " " + y)) {
                    System.out.print(player.getSymbol()); // print "@"


                }
                for (int v = 0; v < vampires.size(); v++) {
                    if (vampires.get(v).getPos().equals(x + " " + y)) {
                        System.out.print(vampires.get(v).getSymbol()); // print "v"

                    }
                }

                System.out.print(".");


        }
        System.out.println();
    }

}
}

Class Main

    package dungeon;

    public class Main {

    public static void main(String[] args) {

        Dungeon d = new Dungeon(5, 5, 1, 14, true); // width of grid, height of grid (grid printed by string "."), vampires, moveRemaining, canVampireMove 

        d.printCoordinate();
        d.printMap();

    }
}

The Output Was

@ 0 0 (player x, y)
v 3 0 (vampire x, y)

@...v..
.....
.....
.....
.....

String @ should have replaced the first . , and v should replaced the third . .

Expected Output

@ 0 0 (player x, y)
v 3 0 (vampire x, y)

@.v..
.....
.....
.....
.....

Answer 1

Problem is that you are printing multiple characters for positions occupied by player and vampire . Your code checks whether the given positions is occupied by player and if it is, prints @ but then it will print the dot anyway.

You should restrict this so that only one character is printed per position. For example something like this.

if (positions is occupied by player) {
    print player
} else if (position is occupied by a vampire) {
    print vampire
} else {
    else print dot
}

Answer 2

There is better way to do this like two dimensional array and hashmap. But this is quick fix. Did not test it but it should work.

public void printMap() {

    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {


                if (player.getPos().equals(x + " " + y)) {
                    System.out.print(player.getSymbol()); // print "@"


                } else if {
                    for (int v = 0; v < vampires.size(); v++) {
                        if (vampires.get(v).getPos().equals(x + " " + y)) {
                            System.out.print(vampires.get(v).getSymbol()); // print "v"

                    }
                }
               } else {
                    System.out.print(".");


        }
        System.out.println();
    }

}
}

Answer 3

I have solved this by creating a boolean method.

public void printMap() {

    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {

            if (player.getPos().equals(x + " " + y)) {
                System.out.print(player.getSymbol());

            } else if (getVampires(x, y)) {
                System.out.print("v");

            } else {
                System.out.print(".");
            }
        }
        System.out.println();
    }

}

public boolean getVampires(int x, int y) {
    for (int v = 0; v < vampires.size(); v++) {
        if (vampires.get(v).getPos().equals(x + " " + y)) {
            return true;
        }
    }

    return false;
}