假设我有一个以下格式的文件:
3
4
1,2,3,4
5,6,7,8
9,10,11,12
文件的前两行表示二维数组的行数和列数。此后，每一行代表二维数组每一行的值。我正在尝试读取此文件并在 java 中创建一个二维整数数组。我尝试了以下代码:
public class PrintSpiral {
private static BufferedReader in = null;
private static int rows = 0;
private static int columns = 0;
private static int [][] matrix = null;
public static void main(String []args) throws Exception {
try {
String filepath = args[0];
int lineNum = 0;
int row=0;
in = new BufferedReader(new FileReader(filepath));
String line = in.readLine();
while(line!=null) {
lineNum++;
if(lineNum==1) {
rows = Integer.parseInt(line);
System.out.println("The number of rows of the matrix are: " + rows);
} else if(lineNum==2) {
columns = Integer.parseInt(line);
System.out.println("The number of columns of the matrix are: " + columns);
matrix = new int[rows][columns];
} else {
String [] tokens = line.split(",");
for (int j=0; j<tokens.length; j++) {
System.out.println("I am filling the row: " + row);
matrix[row][j] = Integer.parseInt(tokens[j]);
}
row++;
}
}
} catch (Exception ex) {
System.out.println("The code throws an exception");
System.out.println(ex.getMessage());
} finally {
if (in!=null) in.close();
}
System.out.println("I am printing the matrix: ");
for (int i=0; i < rows; i++) {
for(int j=0; j < columns; j++)
System.out.print(matrix[i][j]);
System.out.println("");
}
}
}
我看到的输出是:
The number of rows of the matrix are: 3
The number of columns of the matrix are: 3
I am filling the row: 0
I am filling the row: 1
I am filling the row: 2
I am filling the row: 3
The code throws an exception
3
I am printing the matrix:
300
300
300
3 0 0 0 0 0 3 3 0
很明显，java 代码没有正确读取文件。另外，我的代码抛出异常。我不确定是什么原因导致此异常。我似乎无法弄清楚我的代码有什么问题。谢谢!
最佳答案
改变
in = new BufferedReader(new FileReader(filepath));
String line = in.readLine();
while(line!=null) { .....
到
in = new BufferedReader(new FileReader(filepath));
String line = null;
while((line = in.readLine()) !=null) { .....
在每个循环开始时读取一个新行
关于Java 从文件中读取二维数组，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/7797284/