流操作

//先写入文件,后读取
import java.io.*;
public class StreamDemo
{
public static void main(String[] args)
{
   try
   {
    //建立输出流
    DataOutputStream out=
     new DataOutputStream(
      new BufferedOutputStream(
       new FileOutputStream(
        "Example.txt")));
    //写入一个double类型数据
    out.writeDouble(3.1425926);
    //写入一行文本
    out.writeBytes("This was pi");
    out.close();
    //建立输入流
    DataInputStream in=
     new DataInputStream(
      new BufferedInputStream(
       new FileInputStream(
        "Example.txt")));
    //建立输入Reader
    BufferedReader reader=
     new BufferedReader(
      new InputStreamReader(in));
    //读入一个double类型数据
    System.out.println(in.readDouble());
    //读入一行文本
    System.out.println(reader.readLine());
   }
   catch(IOException e)
   {
    System.out.println(e.toString());
   }
}
}