import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class ByteArraySpeichern {

	private boolean writeData(byte[] data, String fileName) {
		File file = new File(fileName);

		FileOutputStream fos = null;
		try {
			fos = new FileOutputStream(file);
			fos.write(data);
			fos.flush();
			return true;
		} catch (FileNotFoundException e) {
			System.err.println(file + " doesn't exist!");
		} catch (IOException e) {
			System.err.println("Problems writing data to " + file);
		} finally {
			try {
				if(fos != null) fos.close();
			}catch(IOException e){}
		}
		return false;
	}

	private byte[] readData(String fileName) {
		File file = new File(fileName);
		FileInputStream fis = null;
		byte[] data = null;
		try {
			fis = new FileInputStream(file);
			data = new byte[(int) file.length()];
			fis.read(data);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				if(fis != null) fis.close();
			} catch (IOException e) {}
		}
		return data;
	}

	public static void main(String[] args) {
		String txt = "Eine Eingabe";
		String fileName = "test";
		ByteArraySpeichern bas = new ByteArraySpeichern();
		if (bas.writeData(new String(txt).getBytes(), fileName))
			System.out.println("'" + txt
					+ "' erfolgreich als byte[] gespeichert");
		String ergebnis = new String(bas.readData(fileName));
		System.out.println("Aus Datei gelesen: '" + ergebnis + "'");
	}
}