One megabyte is 1048576 bytes. Also a BufferedOutputStream won’t make anything faster unless you’re over a network. All flushing is done when you close() then PrintWriter, rendering the BOS useless 
I’ve created this for the writer. It doesn’t work though… And yes, I know, it’s not pretty in the least bit.
package waffles.main;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
public class DataWriter {
public static String[][] writeData;
public static ArrayList<Platform> Platforms = new ArrayList<Platform>();
public static ArrayList<Entity> Robots = new ArrayList<Entity>();
public static ArrayList<ItemWaffle> WaffleCoins = new ArrayList<ItemWaffle>();
public static ArrayList<Bullet> Bullets = new ArrayList<Bullet>();
public static ArrayList<Wall> Walls = new ArrayList<Wall>();
public static ArrayList<Wall> BackgroundWalls = new ArrayList<Wall>();
public static ArrayList<Door> Elevators = new ArrayList<Door>();
public static ArrayList<ArrayList<String>> newData = new ArrayList<ArrayList<String>>();
@SuppressWarnings("unchecked")
public static void DataWriter(ArrayList<ArrayList<?>> LevelData){
//setup
Platforms = (ArrayList<Platform>) LevelData.get(0);
Robots = (ArrayList<Entity>) LevelData.get(1);
WaffleCoins = (ArrayList<ItemWaffle>) LevelData.get(2);
Bullets = (ArrayList<Bullet>) LevelData.get(3);
Walls = (ArrayList<Wall>) LevelData.get(4);
BackgroundWalls = (ArrayList<Wall>) LevelData.get(5);
Elevators = (ArrayList<Door>) LevelData.get(6);
}
public static void CloneFromLevel(){
Platforms = Level.Platforms;
Robots = Level.Robots;
WaffleCoins = Level.WaffleCoins;
Bullets = Level.Bullets;
Walls = Level.Walls;
BackgroundWalls = Level.BackgroundWalls;
Elevators = Level.Elevators;
}
public static void WriteToFile(String filename){
try{
BufferedWriter writer = new BufferedWriter(new FileWriter(filename + ".lvl"));
for (int y = 0;y < newData.size();y++){
for (int x = 0;x < newData.get(y).size();x++){
String inf = null;
inf = newData.get(y).get(x);
if (inf == null)
inf = "0:";
writer.write(inf);
}
writer.newLine();
}
} catch(IOException e){
throw new RuntimeException("Error in creating level file!");
}
}
public static void SaveMatrix(){
// try{
CreateMatrixBase();
//Please ignore the obvious error that i made where i forgot to change all of the gets to their respective lists..
for (int x = 0;x < Platforms.size();x++){
newData.get((int) Platforms.get(x).y).add((int) Platforms.get(x).x, "1:");
}
for (int x = 0;x < Robots.size();x++){
newData.get((int) Platforms.get(x).y).add((int) Platforms.get(x).x, "2:");
}
for (int x = 0;x < WaffleCoins.size();x++){
newData.get((int) Platforms.get(x).y).add((int) Platforms.get(x).x, "3:");
}
for (int x = 0;x < Bullets.size();x++){
newData.get((int) Platforms.get(x).y).add((int) Platforms.get(x).x, "3:");
}
for (int x = 0;x < Walls.size();x++){
newData.get((int) Platforms.get(x).y).add((int) Platforms.get(x).x, "4:");
}
for (int x = 0;x < BackgroundWalls.size();x++){
newData.get((int) Platforms.get(x).y).add((int) Platforms.get(x).x, "5:");
}
for (int x = 0;x < Elevators.size();x++){
newData.get((int) Platforms.get(x).y).add((int) Platforms.get(x).x, "6:");
}
// }catch(Exception e){
//
// throw new RuntimeException("Level is too big!");
// }
}
public static void CreateMatrixBase(){
for (int y = 0; y < 50000;y++){
for (int x = 0;x < 50000; x++){
newData.get(y).add(x,"0:");
}
}
}
}