上机作业——i/o

import java.io.*;

public class delet {
    public static void main(String[]args){
        String str = "212313撒旦 大是";
        File file = new File("data.txt");
        if(file.exists()){
            try {
                file.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }else{
            System.out.println("fill");
        }
        try{
            FileWriter writer = new FileWriter(file,true);
            writer.write(str);
            writer.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        try{
            FileReader reader = null;
            try {
                reader = new FileReader(file);
                char a[] = new char[1024];
                int length = reader.read(a);
                System.out.println(new String(a,0,length));
                reader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            
            
        }
    }
}