NullPointerException异常试图初始化一个二维数组 [英] NullPointerException while trying to initialize a 2d array

问题描述

我得到一个NullPointerException异常试图从文本文件添加值二维数组。第一2值确定的行和列。任何想法是把它扔。忽略异常处理和打印报表。我试图让初始化，然后会回去和牛肉它一点的阵列。

I am getting a nullPointerException trying to add values from a text file to a 2d array. The first 2 values determine the rows and columns. Any ideas what is throwing it. Ignore the exception handling, and the print statements. I am trying to get the array initialized then will go back and beef it up a bit.

public Help(String filename) throws FileNotFoundException,
        InvalidFileFormatException {
    this.filename = filename;

    System.out.println("Reading in file: " + filename);

    String number = "";
    int row = 0;
    int col = 0;
    int count = 0;

    try {
        Scanner inputFile = new Scanner(new File(filename));

        while (inputFile.hasNextInt()) {
            row = Integer.parseInt(inputFile.next());
            col = Integer.parseInt(inputFile.next());
            System.out.println("Row : " + row);
            System.out.println("Col : " + col);
            baseMap = new double[row][col];
            System.out.println(baseMap[2][4]);
            for (int i = 0; i < baseMap.length; i++){
                for (int j = 0; j < baseMap[i].length; j++){
                    baseMap[i][j] = Double.parseDouble(inputFile.next());
                }
            }
        }
System.out.println(baseMap[2][4]);
    } catch (Exception e) {
        System.out.println(e.toString());
    } 

的输出的
读文件：sampleMap2.txt
行：5
西：5
0.0
异常的线程主显示java.lang.NullPointerException

OUTPUT Reading in file: sampleMap2.txt Row : 5 Col : 5 0.0 Exception in thread "main" java.lang.NullPointerException

推荐答案

你期望什么样的价值在这里看到;

What value do you expect to see here;

baseMap = new double[row][col];
System.out.println(baseMap[2][4]);

怎么样，如果排== 1？

How about if row == 1?

还有什么，如果没有更多的数据为：

Also what if there is no more data at:

baseMap[i][j] = Double.parseDouble(inputFile.next());

也许你只是没有足够的数据。

Maybe you just don't have enough data.

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