往D盘中的JAVA复习文件夹中写数据：

数据改了一下哈：

import java.io.*;
import java.util.Scanner;
public class Test {
    public static void main(String[] args) throws IOException {
        String fileName="D:JAVA复习\\grade.txt";
        FileWriter writer = new FileWriter(fileName);
        writer.write("C++ 98\n");
        writer.write("高数 92\n");
        writer.write("大物 92\n");
        writer.write("体育 96\n");
        writer.write("英语 92\n");
        writer.close();
    }
}

从D盘JAVA复习的文件夹里面找到Hello.txt读取文本并显示在屏幕上

import java.io.*;
public class Test {
    public static void main ( String[] args ) {
        String fileName = "D:JAVA复习\\Hello.txt" , line;
        try {
            BufferedReader in=new BufferedReader(new FileReader( fileName));
            line = in.readLine();   //读取一行内容
            while ( line != null ) {
                System.out.println( line );
                line = in.readLine();
            }
            in.close();
        }
        catch ( IOException iox ) {
            System.out.println("Problem reading " + iox.getMessage() );
        }
    }
}