为什么我在这里得到一个NullPointerException

Question

我正在阅读代表迷宫图案的文本文件.每行读入1d char数组,然后将一个1d数组插入到2d char数组中.

在以下方法中获取nullpointerexception

        line = (input.readLine()).toCharArray();

---

private void fillArrayFromFile() throws IOException 
{

    BufferedReader input = new BufferedReader(new FileReader("maze.txt"));

    //Read the first two lines of the text file and determine the x and y length of the 2d array
    mazeArray = new char[Integer.parseInt(input.readLine())][Integer.parseInt(input.readLine())];

    char [] line = new char[10];

    //Add each line of input to mazeArray
    for (int x = 0; x < mazeArray[0].length; x++) 
    {
        line = (input.readLine()).toCharArray();
        System.out.print(x + " : ");
        System.out.println(line);
        mazeArray[x] = line;
    }
}

Answer 1

BufferedReader.readLine()null当没有更多输入被读取时返回.有关更多信息,请参阅Java文档.