我在第二个类（MazeSolver）上遇到问题，无法从第一个类（MazeInput）中获取行和列的值。这导致我在MazeSolver中的drawMaze（）方法中出现ArrayOutOfBoundsExceptions和NullPointerExceptions。我理解为什么会发生这些错误，由于缺乏对如何将字段传递给其他类的理解，我对于如何解决它一无所知。你们可爱的家伙能指出我要去哪里了吗？
public class LA2_MazeInput {
private int rows;
private int cols;
public LA2_MazeInput() {
this.rows = getNumRows();
this.cols = getNumCols(rows);
}
private int getNumRows() {
int rows = 0;
String input;
input = JOptionPane.showInputDialog(
"Please enter the number of rows (5-10) for the maze.");
rows = Integer.parseInt(input);
return rows;
}
private int getNumCols(int numRows) {
int cols = 0;
String input;
input = JOptionPane.showInputDialog(
"Please enter the number (5-10) of columns for the maze."
+ "\n(Value cannot be the same as the number of rows.)");
cols = Integer.parseInt(input);
return cols;
}
public void initializeMazeSolver(/*MazeSolver solver*/) {
LA2_MazeSolver ms = new LA2_MazeSolver();
ms.setNumRows(this.rows);
ms.setNumCols(this.cols);
}
}
public class LA2_MazeSolver {
private int rows;
private int cols;
private String[][] maze;
public LA2_MazeSolver() {
this.maze = new String[rows][cols];
}
public void setNumRows(int numRows) {
this.rows = numRows;
}
public void setNumCols(int numCols) {
this.cols = numCols;
}
public int getNumRows() {
return this.rows;
}
public int getNumCols() {
return this.cols;
}
public void drawMaze() {
Random r = new Random();
maze[0][0] = "S";
maze[rows - 1][cols - 1] = "D";
int limit = ((rows * cols) / 3);
for (int i = r.nextInt(limit) + 1; i < limit; i++) {
maze[r.nextInt(rows - 1)][r.nextInt(cols - 1)] = "#";
}
for (int i = 0; i < maze.length; i++) {
for (int c = 0; c < maze[0].length; c++) {
if (!(maze[i][c].matches("#")) && !(maze[i][c].matches("S")) && !(maze[i][c].matches("D"))) {
maze[i][c] = Integer.toString(r.nextInt(100) + 1);
}
}
}
for (int i = 0; i < maze.length; i++) {
for (int c = 0; c < maze[0].length; c++) {
System.out.print(maze[i][c] + " ");
}
System.out.println();
}
}
}
最佳答案
您的MazeSolver构造函数使用[0][0]的大小初始化二维数组。之后，您尝试设置行和列，这时为时已晚。
LA2_MazeSolver ms = new LA2_MazeSolver(); // constructor of LA2_MazeSolver is called
ms.setNumRows(this.rows); // does nothing for the array
ms.setNumCols(this.cols); // does nothing for the array
为了解决这个问题，您可以将参数与构造函数一起传递。
public LA2_MazeSolver(int rows, int cols) {
this.maze = new String[rows][cols];
this.rows = rows; // in case you want them to store
this.cols = cols; // in case you want them to store
}
反模式：
public LA2_MazeSolver() {
}
public void setNumRows(int numRows) {
this.rows = numRows;
}
public void setNumCols(int numCols) {
this.cols = numCols;
}
public void init(){
this.maze = new String[rows][cols];
}
会这样初始化
LA2_MazeSolver ms = new LA2_MazeSolver();
ms.setNumRows(this.rows);
ms.setNumCols(this.cols);
ms.init();