使用 BufferedReader 从抛出 NullPointerException 的二维数组中获取值

Question

I need to grab integer values from a.txt file using the BufferedReader, and then save them to a 2D int array. For some reason, when I get to the .trim() line, it throws a NullPointerException. Each of the numbers in my array are separated by a space in the file:

90 47 110 95 95 
101 87 
54 0 38 12 

Here is the broken code I have for reading then saving the integers:

int2DArr = new int[int2Drows][int2Dcolumns];
        String s;
        while((s = br.readLine()) != null){
            for(int i = 0; i<int2DArr.length; i++){
                String[] currLine = br.readLine().trim().split(" "); //throwing error here
                for(int j = 0; j<currLine.length; j++){
                    int2DArr[i][j] = Integer.parseInt(currLine[j]);
                }
            }
        }

Any help would be greatly appreciated!

Answer 1

I think the problem is that there is an extra readLine() . You are already reading the next line in the while loop. So inside the loop you should use the s instead of reading the next line. With your current code, you are reading 2 lines per iteration in the while loop but you intended to read 1 line per iteration.

Note the change just before the trim call.

int2DArr = new int[int2Drows][int2Dcolumns];
String s;
while((s = br.readLine()) != null){
  for(int i = 0; i<int2DArr.length; i++){
    String[] currLine = s.trim().split(" ");
    for(int j = 0; j<currLine.length; j++){
      int2DArr[i][j] = Integer.parseInt(currLine[j]);
    }
  }
}