java - java中比较十进制值

Question

我正在尝试从逗号分隔的 CVS 文件中获取某些值。到目前为止，这是我的代码:

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.math.BigDecimal;

class A {

    public static void main(String args[]){

        BufferedReader br = null;
        try {

            String sCurrentLine;

            br = new BufferedReader(new FileReader("sample.csv"));

            double start = 20659200000.000000;
                    DecimalFormat df = new DecimalFormat("#.######");
                    df.format(start);
                    int i = 0;
                    while ((sCurrentLine = br.readLine()) != null) {
                            String[] tmp = sCurrentLine.split(",");
                            //System.out.println(tmp[0]);
                    BigDecimal bg1, bg2;
                    bg1 = new BigDecimal(Double.parseDouble(new
                         BigDecimal(tmp[0]).toPlainString()));
                    bg2 = new BigDecimal(start);
                            if(bg1.equals(bg2))
                            {
                                    //System.out.println("Inside if");
                                    //System.out.println(tmp[0]);
                                    System.out.println(sCurrentLine);
                                    start = start + 0.000100;
                                    df.format(start);
                                    i = i + 1;
                            }
                    }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                    if (br != null)br.close();
            } catch (IOException ex) {
                    ex.printStackTrace();
            }
        }
    }
}

我正在尝试读取这样的示例文件:

20659200000.000000,1.389320
20659200000.000000,1.318758
20659200000.000000,1.361239
20659200000.000000,1.379709
20659200000.000100,1.389320
20659200000.000100,1.357912
20659200000.000100,1.365672
20659200000.000100,1.374912
20659200000.000100,1.318937
20659200000.000100,1.355331
20659200000.000200,1.370660
20659200000.000200,1.365118
20659200000.000200,1.364933

我只想从左列中选择一个值(第一个)。目前，if 条件仅被访问一次。

我更改了 if 条件和 equals 方法，现在它仅适用于前三个迭代。更新起始值时出错。

有什么想法吗？谢谢。

Answer 1

以下是您应该在读取循环中执行的操作:

while ((sCurrentLine = br.readLine()) != null) {
    String[] tmp = sCurrentLine.split(",");
    // here only use tmp[0] if you just want to pick the first column
    // you could parse it to a double and calculate the stuff you want
    System.out.println(tmp[0]);
}