(模板)java文件读写与保留小数

import java.math.*;import java.text.*;import java.util.*;import java.io.*;public class Main {public static void main(String []args) throws IOException {Scanner cin = new Scanner(new File("trains.in"));          PrintWriter cout = new PrintWriter(new File("trains.out"));                      double c = 3.155;BigDecimal t = BigDecimal.valueOf(3.155);java.text.DecimalFormat myFormat = new java.text.DecimalFormat("#.00");cout.println(myFormat.format(t));        cin.close();          cout.close();}}