Java学习——读写txt文件

package HHH;
import java.io.*;
import static java.lang.System.out;

public class OpenFile {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        try{
            FileInputStream rf = new FileInputStream("openFile.txt");
            FileOutputStream wf = new FileOutputStream("write.txt");
            int n=512;
            byte buffer[] = new byte[n];//buffer就是个byte类型数组
            while((rf.read(buffer,0,n) != -1) && (n>0))//读取输入流
            {
                out.print(new String(buffer));//在屏幕中输出,强制转换成字符串
                wf.write(buffer,0,buffer.length);

            }
            out.println();
            rf.close();
            wf.close();
        }catch(IOException ioe){
            out.println(ioe);
        }catch(Exception e){
            out.println(e);
        }
    }

}

package HHH;

import java.util.*;
import java.io.*;

public class ScannerTest2 {

    public static void main(String[] args) throws IOException
    {
        // TODO Auto-generated method stub
        double sum = 0.0;
        int count = 0;
        FileWriter fout = new FileWriter("text.txt");
        fout.write("2 2.2 3 3.3 4 4.5 done");
        fout.close();

        FileReader fin = new FileReader("text.txt");

        Scanner in = new Scanner(fin);
        while(in.hasNext())
        {
            if(in.hasNextDouble())
            {
                System.out.println(in.nextDouble());
                sum = sum + in.nextDouble();
                count++;
            }
            else
            {
                String str = in.next();
                System.out.println(str);
                if(str.equals("done"))
                {
                    break;
                }
                else
                {
                    System.out.println("文件格式错误");
                    return ;
                }
            }
        }
        fin.close();
        System.out.println("文件中数据的平均数是:"+ sum / count);

    }
}