Database

import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;

public class Database {
    private static final int MAX_FILE=100;
    private FileWritable[] list = new FileWritable[MAX_FILE];
    public Database(){

    }
    public void addDatabase(FileWritable row){
        for(int i=0;i<list.length;i++){
            if(list[i]!=null){
                list[i++]=row;
                break;
            }
        }
    }
    public void removeDatabase(FileWritable row){
        for(int i=0;i<list.length;i++){
            if(row.equals(list[i])){
                list[i]=null;
            }
        }

    }
    public void writeAll(String filename){
        try(BufferedWriter bw=new BufferedWriter(new FileWriter("text.txt"))){
            for (FileWritable row:list){
                if(row!=null){
                    row.writeToFile(bw);
                }
            }
        }catch(IOException e){
            e.printStackTrace();
        }
    }

    public static void main(String[] args){
        Database database=new Database();
        database.addDatabase(new Student("apple",123));
        database.writeAll("text.txt");
    }

}