接收键盘输入的字符串，用FileWirter类将字符串写入文件，用FileReader类读出文件内容显示在屏幕上

public class SY63 {
    public static void main(String[] args) throws Exception {
        System.out.print("请输入字符串:");
        Scanner in = new Scanner(System.in);
        String st = in.nextLine();
        
        FileWriter fw = new FileWriter("d:\\test.txt");
        fw.write(st);
        fw.close();
        
        FileReader fr = new FileReader("d:\\test.txt");
        char[] bchar= new char[1024];
        int len = 0;
        while((len = fr.read(bchar)) != -1){
            System.out.print(new String(bchar,0,len));
        }
        fr.close();
    }
}