Java方法调用另一个类的方法

Question

这是主要课程：

public class Sudoku extends JFrame {
    MenuBar Bar;
MenuItem itemFile[];
MenuItem itemHelp[];
Menu file;
Menu help;
public Sudoku() {
    super("Sudoku");
    setLayout(new FlowLayout());
    setResizable(false);
    itemFile =new MenuItem[2];
    itemHelp =new MenuItem[2];
    itemFile[0]=new MenuItem("New");
    itemFile[1]=new MenuItem("Exit");
    itemHelp[0]= new MenuItem("Rules");
    itemHelp[1]= new MenuItem("Creators");
    file=new Menu("File");
    help=new Menu("Help");
    file.add(itemFile[0]);
    help.add(itemHelp[0]);
    file.add(itemFile[1]);
    help.add(itemHelp[1]);
    Bar =new MenuBar();
    Bar.add(file);
    Bar.add(help);
    setMenuBar(Bar);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    getContentPane().setLayout(new BorderLayout());

    Game game = new Game();

    ButtonController buttonController = new ButtonController(game);
    ButtonPanel buttonPanel = new ButtonPanel();
    buttonPanel.setController(buttonController);
    add(buttonPanel, BorderLayout.EAST);

    SudokuPanel sudokuPanel = new SudokuPanel();
    SudokuController sudokuController = new SudokuController(sudokuPanel, game);
    sudokuPanel.setGame(game);
    sudokuPanel.setController(sudokuController);
    add(sudokuPanel, BorderLayout.CENTER);

    game.addObserver(buttonPanel);
    game.addObserver(sudokuPanel);

    pack();
    setLocationRelativeTo(null);
    setVisible(true);
}

    public boolean action(Event evt, Object arg){
    if(evt.target instanceof MenuItem){
        String text=(String)arg;
        System.out.println("Selected="+arg);
        if(text.equals("Exit"))
            System.exit(0);
        else if(text.equals("New"))
            // Get newGame() of Game class to run here.
    }

    return true;
}

这是游戏类：

package sudoku.model;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Observable;

public class Game extends Observable {
private int[][] solution;      
private int[][] game;           
private boolean[][] check;      
private int selectedNumber;     
private boolean help;          


public Game() {
    newGame();
    check = new boolean[9][9];
    help = true;
}

public void newGame() {
    solution = generateSolution(new int[9][9], 0);
    game = generateGame(copy(solution));
    setChanged();
    notifyObservers(UpdateAction.NEW_GAME);
}

public void checkGame() {
    selectedNumber = 0;
    for (int y = 0; y < 9; y++) {
        for (int x = 0; x < 9; x++)
            check[y][x] = game[y][x] == solution[y][x];
    }
    setChanged();
    notifyObservers(UpdateAction.CHECK);
}

public void setHelp(boolean help) {
    this.help = help;
    setChanged();
    notifyObservers(UpdateAction.HELP);
}

public void setSelectedNumber(int selectedNumber) {
    this.selectedNumber = selectedNumber;
    setChanged();
    notifyObservers(UpdateAction.SELECTED_NUMBER);
}

public int getSelectedNumber() {
    return selectedNumber;
}

public boolean isHelp() {
    return help;
}

public boolean isSelectedNumberCandidate(int x, int y) {
    return game[y][x] == 0 && isPossibleX(game, y, selectedNumber)
            && isPossibleY(game, x, selectedNumber) && isPossibleBlock(game, x, y, selectedNumber);
}

public void setNumber(int x, int y, int number) {
    game[y][x] = number;
}

public int getNumber(int x, int y) {
    return game[y][x];
}

public boolean isCheckValid(int x, int y) {
    return check[y][x];
}

private boolean isPossibleX(int[][] game, int y, int number) {
    for (int x = 0; x < 9; x++) {
        if (game[y][x] == number)
            return false;
    }
    return true;
}

private boolean isPossibleY(int[][] game, int x, int number) {
    for (int y = 0; y < 9; y++) {
        if (game[y][x] == number)
            return false;
    }
    return true;
}

private boolean isPossibleBlock(int[][] game, int x, int y, int number) {
    int x1 = x < 3 ? 0 : x < 6 ? 3 : 6;
    int y1 = y < 3 ? 0 : y < 6 ? 3 : 6;
    for (int yy = y1; yy < y1 + 3; yy++) {
        for (int xx = x1; xx < x1 + 3; xx++) {
            if (game[yy][xx] == number)
                return false;
        }
    }
    return true;
}

private int getNextPossibleNumber(int[][] game, int x, int y, List<Integer> numbers) {
    while (numbers.size() > 0) {
        int number = numbers.remove(0);
        if (isPossibleX(game, y, number) && isPossibleY(game, x, number) && isPossibleBlock(game, x, y, number))
            return number;
    }
    return -1;
}

private int[][] generateSolution(int[][] game, int index) {
    if (index > 80)
        return game;

    int x = index % 9;
    int y = index / 9;

    List<Integer> numbers = new ArrayList<Integer>();
    for (int i = 1; i <= 9; i++) numbers.add(i);
    Collections.shuffle(numbers);

    while (numbers.size() > 0) {
        int number = getNextPossibleNumber(game, x, y, numbers);
        if (number == -1)
            return null;

        game[y][x] = number;
        int[][] tmpGame = generateSolution(game, index + 1);
        if (tmpGame != null)
            return tmpGame;
        game[y][x] = 0;
    }

    return null;
}

private int[][] generateGame(int[][] game) {
    List<Integer> positions = new ArrayList<Integer>();
    for (int i = 0; i < 81; i++)
        positions.add(i);
    Collections.shuffle(positions);
    return generateGame(game, positions);
}

private int[][] generateGame(int[][] game, List<Integer> positions) {
    while (positions.size() > 0) {
        int position = positions.remove(0);
        int x = position % 9;
        int y = position / 9;
        int temp = game[y][x];
        game[y][x] = 0;

        if (!isValid(game))
            game[y][x] = temp;
    }

    return game;
}

private boolean isValid(int[][] game) {
    return isValid(game, 0, new int[] { 0 });
}

private boolean isValid(int[][] game, int index, int[] numberOfSolutions) {
    if (index > 80)
        return ++numberOfSolutions[0] == 1;

    int x = index % 9;
    int y = index / 9;

    if (game[y][x] == 0) {
        List<Integer> numbers = new ArrayList<Integer>();
        for (int i = 1; i <= 9; i++)
            numbers.add(i);

        while (numbers.size() > 0) {
            int number = getNextPossibleNumber(game, x, y, numbers);
            if (number == -1)
                break;
            game[y][x] = number;

            if (!isValid(game, index + 1, numberOfSolutions)) {
                game[y][x] = 0;
                return false;
            }
            game[y][x] = 0;
        }
    } else if (!isValid(game, index + 1, numberOfSolutions))
        return false;

    return true;
}

private int[][] copy(int[][] game) {
    int[][] copy = new int[9][9];
    for (int y = 0; y < 9; y++) {
        for (int x = 0; x < 9; x++)
            copy[y][x] = game[y][x];
    }
    return copy;
}
}

我想从我的菜单栏中点击“新建”（其操作在主类中），newGame（）;要执行的Game类的方法。我尝试了很多方法，但都失败了......真是太头疼......

有什么想法吗？

Answer 1

在构造函数中，您创建了Game对象的实例 - 但它在方法结束时超出了范围。你应该在Sudoku类中保留一个引用：

public class Sudoku extends JFrame {
    ...
    private Game game;

    public Sudoku() {
        ...
        game = new Game();

然后：

public boolean action(Event evt, Object arg) {
    if(evt.target instanceof MenuItem) {
        String text=(String)arg;
        System.out.println("Selected="+arg);
        if(text.equals("Exit")) {
            System.exit(0);
        } else if(text.equals("New")) {
            game.newGame();
        }
    }
    return true;
}

Answer 2

添加“Game”对象作为主类的成员类，然后您可以在班级的任何位置访问其方法：

public class Sudoku extends JFrame {
     private Game game;
     // rest of your Sudoku class code as it currently is, but change:
     Game game = new Game();
     // to:
     this.game = new Game();
     // In your 'action' method, you can now call like this:
     this.game.newGame();