Question

我收到错误：

 Exception in thread "main" java.lang.IllegalArgumentException: bound must be positive
    at java.util.Random.nextInt(Random.java:388)
    at MortalCoilSolver.findSolutionPath(MortalCoilSolver.java:63)
    at MortalCoilSolver.solve(MortalCoilSolver.java:48)
    at MortalCoilSolver.go(MortalCoilSolver.java:33)
    at MortalCoilSolver.main(MortalCoilSolver.java:22)

使用代码：

import java.io.*;
import java.net.URL;
import java.util.Random;

// program to solve the puzzle at http://www.hacker.org/coil/
 public class MortalCoilSolver {
private static int[][] offsets = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}};
private static char[] offNames = {'L', 'D', 'R', 'U'};
private Random r = new Random();
private static String name, pw;
private int targetFill, boardX, boardY, startX = -1, startY = -1, board[][];
private String boardString;

public static void main(String[] args) throws Exception {
    if (args.length != 2) {
        System.out.println("usage:\nMortalCoilSolver name pw\n");
        return;
    }
    name = args[0]; pw = args[1];
    MortalCoilSolver mcs = new MortalCoilSolver();
    while (true) {
        mcs.go();
        Thread.sleep(2000);
    }
}

private void go() throws Exception {
    URL u;
    u = new URL("http://www.hacker.org/coil/index.php?name=" + name + "&password=" + pw);
    InputStream is = u.openStream();
    input2level(is);
    System.out.println(this);
    solve();
}

public String toString() {
    String s = "";
    for (int j = 0; j < boardY; j++) {
        for (int i = 0; i < boardX; i++) {
            s += board[i][j] > 0 ? 'X' : '.';
        }
        if (j < boardY - 1) s += '\n';
    }
    return s;
}

public boolean solve() throws Exception {
    String path = findSolutionPath();
    System.out.println("solved at (" + startX + ", " + startY + ") : " + path);
    URL u;
    u = new URL("http://www.hacker.org/coil/index.php?name=" + name +
            "&password=" + pw + "&path=" + path + "&x=" + startX + "&y=" + startY);
    InputStream is = u.openStream();
    BufferedReader in = new BufferedReader(new InputStreamReader(is));
    while ((in.readLine()) != null) { }
    is.close();
    return false;
}

private String findSolutionPath() {
    while (true) { // search until done
        parseBoardString(); // reset board
        startX = r.nextInt(boardX); startY = r.nextInt(boardY); // random start
        if (!goodSquare(startX, startY)) continue;
        int x = startX, y = startY, fill = 1;
        String path = ""; // remember our path
        loop: while (true) {
            int tdir = r.nextInt(4); // choose random direction
            for (int dloop = 0; dloop < 3; dloop++) {
                int dir = (dloop + tdir) % 4;
                int offx = offsets[dir][0];
                int offy = offsets[dir][1];
                if (!goodSquare(x + offx, y + offy)) continue; // blocked
                path += offNames[dir];
                while (true) { // move until we hit something
                    board[x][y] = 2;
                    x += offx; y += offy;
                    if (!goodSquare(x, y)) break;
                    if (++fill == targetFill) return path; // got it
                }
                x -= offx; y -= offy; // we went one too far!
                continue loop;
            }
            break;
        }
    }
}

private boolean goodSquare(int x, int y) {
    if (x < 0 || y < 0 || x >= boardX || y >= boardY) return false;
    return (board[x][y] == 0);
}

private void input2level(InputStream is) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(is));
    String line;
    while ((line = in.readLine()) != null) {
        if (!line.startsWith("    <param name=\"FlashVars\"")) continue;
        line = line.split("\"")[3]; // get just the value
        String[] ss = line.split("(=|&)"); // split up the name value pairs
        boardX = Integer.parseInt(ss[1]); boardY = Integer.parseInt(ss[3]);
        board = new int[boardX][boardY];
        boardString = ss[5];
        parseBoardString();
    }
    in.close();
}

private void parseBoardString() {
    int cnt = 0;
    for (int x = 0; x < boardX; x++)
        for (int y = 0; y < boardY; y++) {
            int a = boardString.charAt(x + y * boardX) == 'X' ? 1 : 0;
            board[x][y] = a;
            cnt += a;
        }
    targetFill = (boardX * boardY) - cnt; // how many squares we need to fill
}

}

Answer 1

首先，阅读您的错误消息并尝试理解它。第一行告诉您错误是什么

bound must be positive

以及下一个问题的方法和位置 -

Random.nextInt(Random.java:388)

这是在Java库中，因此请查看堆栈跟踪，直到找到自己的方法之一

at MortalCoilSolver.findSolutionPath(MortalCoilSolver.java:63)

查看代码的第63行

startX = r.nextInt(boardX); startY = r.nextInt(boardY); // random start

将r.nextInt放在一起，调用boardX或boardY的零值或负值。快速查看代码显示这些值的默认值仍为0。

求解器返回错误：如何处理它

1 个答案: