java - java中Integer[][](矩阵)的Arraylist

Question

我在 Java 中定义了一个矩阵 (Integer[][]) 的 ArrayList。当我向 ArrayList 添加新矩阵时，它会将所有变量更改为最后一个矩阵。

我的意思是当我添加

0 4 4 2
0 4 4 2
1 2 3 4
4 5 9 7

然后添加

1 4 7 8
0 1 2 3
4 5 6 7
4 1 2 3

当我打印这样的元素时:

1 4 7 8
0 1 2 3
4 5 6 7
4 1 2 3
-------
1 4 7 8
0 1 2 3
4 5 6 7
4 1 2 3

那么我应该为此做什么呢？这是我的代码:

private Integer matrix[][] = new Integer[4][4];

public Integer[][] right(Integer[][] M) {
        for (int k = 0; k < 4; k++)
            for (int i = 0; i < 4; i++)
                for (int j = 0; j < 3; j++) {
                    if (M[i][j] != 0 && M[i][j + 1] == 0) {
                        M[i][j + 1] += M[i][j];
                        M[i][j] = 0;
                        new_tile = true;
                    }
                }
        for (int i = 0; i < 4; i++)
            for (int j = 3; j > 0; j--) {
                if (M[i][j] == M[i][j - 1] && M[i][j] != 0 && M[i][j - 1] != 0) {
                    M[i][j] += M[i][j - 1];
                    M[i][j - 1] = 0;
                    new_tile = true;
                }
            }
        for (int k = 0; k < 4; k++)
            for (int i = 0; i < 4; i++)
                for (int j = 0; j < 3; j++) {
                    if (M[i][j] != 0 && M[i][j + 1] == 0) {
                        M[i][j + 1] += M[i][j];
                        M[i][j] = 0;
                        new_tile = true;
                    }
                }
        return M;
    }


static void printMatrix(Integer[][] matrix) {
    for (int i = 0; i < matrix.length; i++) {
        for (int j = 0; j < matrix[0].length; j++) {
            System.out.print(matrix[i][j]);
        }
        System.out.println();
    }
}

/**
 * Print the elements in a matrix list
 */
static void printMatrices(ArrayList<Integer[][]> matrices) {
    for (Integer[][] matrix : matrices) {
        printMatrix(matrix);
        System.out.println("--------");
    }
}
public void solve() {

    Integer[][] temp = right(matrix);
    printMatrix(temp);
    if (new_tile)
        visited_nodes.add(temp);
    else {
        printMatrices(visited_nodes);
    }
    refresh();
}

    @Override
    public void actionPerformed(ActionEvent e) {

        solve();
        repaint();
    }

每 100 毫秒调用一次求解方法。

Answer 1

您实际上总是修改相同的矩阵实例。

更改right()方法，使其在每次调用时创建一个新矩阵:

public Integer[][] right(Integer[][] M) {
    Integer[][] newM = new Integer[4][4];

    // modify newM in your algo instead of M
    // Showing only the first bloc
    for (int k = 0; k < 4; k++)
        for (int i = 0; i < 4; i++)
            for (int j = 0; j < 3; j++) {
                if (M[i][j] != 0 && M[i][j + 1] == 0) {
                    newM[i][j + 1] = M[i][j + 1] + M[i][j];
                    newM[i][j] = 0;
                    new_tile = true;
                }
            }
    //...
    return newM;
}