java - 文件中的矩阵

Question

我正在尝试从文本文件创建矩阵。问题是，当缓冲读取器函数 readline() 解析完文件的第一行时，它会到达第二行，但它会将其读取为空，但事实并非如此。

void covar()
    {
        double [][]covar=new double[10][5];
        int i=0;
        int j=0;
        try
        {
            FileInputStream fstream = new FileInputStream("class 1\\feature_vector.txt");
            DataInputStream in = new DataInputStream(fstream);
            BufferedReader br = new BufferedReader(new InputStreamReader(in));
            String input;

            while((input=br.readLine())!= null)
            {               
                String [] temp=input.split(",");
                //System.out.println(input.split(",").length);
                covar[i][j]= new Double(temp[0]);
                covar[i+1][j]=new Double(temp[1]);
                covar[i+2][j]=new Double(temp[2]);
                covar[i+3][j]=new Double(temp[3]);
                covar[i+4][j]=new Double(temp[4]);
                //i=0;
                j++;
            }

            in.close();
        }
        catch(Exception e)

        {
            e.printStackTrace();

        }

以上是代码。文件名是完美的，流也没有任何问题。你们能帮我解决一下这有什么问题吗？

这是文件的内容:

0.75,321.0,0.22429906,0.97507787,1.966202512778112
0.33333334,135.0,-0.014814815,1.0,5.323770568766052
0.64285713,311.0,0.025723472,1.0,4.764298570227433
0.6,188.0,0.03723404,1.0,4.7349608150168105
0.25,189.0,0.16931216,0.98941797,7.15681209803803
0.71428573,194.0,-0.26804122,0.96391755,5.1654456838422425
0.6,173.0,0.028901733,1.0,6.54275787030257
0.2857143,257.0,0.031128405,1.0,6.095356508899233
0.23076923,197.0,-0.04568528,1.0,3.784908227189768
0.18181819,231.0,0.17316018,0.987013,5.956322938602553

Answer 1

有两件事明显错误:

• 您不需要变量i，因为其中一个维度是固定的，并且您“展开”循环五次
• 您交换了索引:j 应该放在第一位，即从 0 更改为 9 的索引。

例如:

String [] temp=input.split(",");
covar[j][0] = new Double(temp[0]);
covar[j][1] =new Double(temp[1]);
covar[j][2] =new Double(temp[2]);
covar[j][3] =new Double(temp[3]);
covar[j][4] =new Double(temp[4]);

您可以放回循环以缩短代码:

String [] temp=input.split(",");
for (int i = 0 ; i != 5 ; i++) {
    covar[j][i] = new Double(temp[i]);
}