如何修复 Java 中的“索引 5 超出长度 5 的范围”错误

Question

我正在研究 CCC 2018 Robo Thieves 问题的解决方案，它是原始问题的简化版本。我的问题是，当我执行我的代码时，它会给我这个“索引 5 超出长度 5 的范围”，我不确定它为什么会发生。我的程序执行了一半，然后出现这个错误。

import java.util.*;

public class RoboThieves {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        ArrayList<Integer> rowPos = new ArrayList<Integer>();
        ArrayList<Integer> colPos = new ArrayList<Integer>();
        int sRow = -1; // robot pos
        int sCol = -1;
        int dotCounter = 0;
        int stepCounter = 0;

        int rowSize = sc.nextInt();
        int colSize = sc.nextInt();
        char[][] factoryGrid = new char[rowSize][colSize];

        for (int i = 0; i < rowSize; i++) {

            String rowChars = sc.next().toUpperCase();

            for (int j = 0; j < colSize; j++) {

                factoryGrid[i][j] = rowChars.charAt(j);
            }

        }

        // check to see if the grid was inputted properly (with square brackets)
        /*
         * for (char [] row: factoryGrid) { System.out.println(Arrays.toString(row)); }
         */

        // check to see if the grid was inputted properly (as inputted)
        for (int i = 0; i < rowSize; i++) {
            for (int j = 0; j < colSize; j++) {

                System.out.print(factoryGrid[i][j]);
            }
            System.out.println();
        }

        // locate dots and store their row and col in arraylists
        for (int i = 0; i < rowSize; i++) {

            for (int j = 0; j < colSize; j++) {
                if (factoryGrid[i][j] == '.') {
                    rowPos.add(i);
                    colPos.add(j);
                    dotCounter++;
                }
            }

        }

        // print dot location to check
        for (int i = 0; i < rowPos.size(); i++) {
            System.out.println("Dot Position = " + "(" + rowPos.get(i) + "," + colPos.get(i) + ")");
        }

        // locate robot position
        for (int i = 0; i < rowSize; i++) {

            for (int j = 0; j < colSize; j++) {
                if (factoryGrid[i][j] == 'S')
                    sRow = i;
                    sCol = j;
            }

        }

        // print camera location to check
        System.out.println("Camera Position = " + "(" + sRow + "," + sCol + ")");

        //System.out.println(dotCounter); // test to see if counter works

        char above = getAbove(factoryGrid, sRow, sCol);
        char right = getRight(factoryGrid, sRow, sCol);
        char below = getBelow(factoryGrid, sRow, sCol);
        char left = getLeft(factoryGrid, sRow, sCol);

        if (above == '.') {

            boolean canMove = check360(factoryGrid, sRow, sCol);
            // check if camera is around dot
            if (canMove == true) {
                // set robot position to dot position and old position to W
                sRow = sRow - 1;
                // sCol = sCol;

                factoryGrid[sRow][sCol] = 'W';

                dotCounter--;
                stepCounter++;

            } else {
                // this is if there is a camera in the 360 radius of the open space
                System.out.println("You cannot move to the space beside because there is a camera in your sightline!");
            }

        } else if (right == '.') {

            boolean canMove = check360(factoryGrid, sRow, sCol);
            // check if camera is around dot
            if (canMove == true) {
                // set robot position to dot position and old position to W
                // sRow = sRow;
                sCol = sCol + 1;

                factoryGrid[sRow][sCol] = 'W';

                dotCounter--;
                stepCounter++;

            } else {
                // this is if there is a camera in the 360 radius of the open space
                System.out.println("You cannot move to the space beside because there is a camera in your sightline!");
            }

        } else if (below == '.') {

            boolean canMove = check360(factoryGrid, sRow, sCol);
            // check if camera is around dot
            if (canMove == true) {
                // set robot position to dot position and old position to W
                sRow = sRow + 1;
                // sCol = sCol;

                factoryGrid[sRow][sCol] = 'W';

                dotCounter--;
                stepCounter++;

            } else {
                // this is if there is a camera in the 360 radius of the open space
                System.out.println("You cannot move to the space beside because there is a camera in your sightline!");
            }

        } else if (left == '.') {
            boolean canMove = check360(factoryGrid, sRow, sCol);
            // check if camera is around dot
            if (canMove == true) {
                // set robot position to dot position and old position to W
                // sRow = sRow;
                sCol = sCol - 1;

                factoryGrid[sRow][sCol] = 'W';

                dotCounter--;
                stepCounter++;

            } else {
                // this is if there is a camera in the 360 radius of the open space
                System.out.println("You cannot move to the space beside because there is a camera in your sightline!");
            }
        } else {

            System.out.println(
                    "The robot cannot move to any spaces try inputting a factory layout that can produce an answer.");

        } // end if above dot (yes)

        System.out.println(stepCounter);

        for (int i = 0; i < rowSize; i++) {
            for (int j = 0; j < colSize; j++) {

                System.out.print(factoryGrid[i][j]);
            }
            System.out.println();
        }

    } // end main method

    public static char getLeft(char[][] factGrid, int cRow, int cCol) {
        return factGrid[cRow][(cCol - 1)];

    }

    public static char getAbove(char[][] factGrid, int cRow, int cCol) {
        return factGrid[(cRow - 1)][(cCol)];

    }

    public static char getBelow(char[][] factGrid, int cRow, int cCol) {
        return factGrid[cRow + 1][cCol];

    }

    public static char getRight(char[][] factGrid, int cRow, int cCol) {
        return factGrid[cRow][(cCol + 1)];

    }

    public static boolean check360(char[][] factGrid, int cRow, int cCol) {
        boolean canMove = true;

        char left = getLeft(factGrid, cRow, cCol);
        char above = getAbove(factGrid, cRow, cCol);
        char right = getRight(factGrid, cRow, cCol);
        char below = getBelow(factGrid, cRow, cCol);

        if (left == 'C' || above == 'C' || right == 'C' || below == 'C') {
            canMove = false;
        }
        return canMove;
    }

} // end main program

Answer 1

乍一看，我认为问题可能在于您的 getLeft()、getAbove()、getRight() 和 getBelow() 方法。

在这些方法中，你给它一个 cRow 和 cCol 的值并加或减 1。但是，你需要确保你正在查询的索引不超过双精度数组的大小 factGrid em>，或低于 0。

例如，在您的 getRight() 方法中，您可以尝试：

public static char getRight(char[][] factGrid, int cRow, int cCol) {
    if(factGrid[0].length > (cCol + 1)) {
        return factGrid[cRow][(cCol + 1)];
    } else {
        return '';
    }
}