Java

import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;

import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.border.EmptyBorder;
import javax.swing.filechooser.FileFilter;



public class GUI extends JFrame {

	private JPanel contentPane;
	private JMenuItem menuSpeichern;
	private JMenuItem menuOeffnen;
	private JTextArea eingabeArea;
	private JFileChooser oeffnen;
	private JFileChooser speichern;
	private String speichernText;
	private String filename;
	private FileFilter filter;

	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					GUI frame = new GUI();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	public GUI() {
		setResizable(false);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 831, 657);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		setContentPane(contentPane);
		contentPane.setLayout(null);

		JMenuBar menuBar = new JMenuBar();
		menuBar.setBounds(0, 0, 815, 21);
		contentPane.add(menuBar);

		JMenu mnDatei = new JMenu("Datei...");
		menuBar.add(mnDatei);

		menuSpeichern = new JMenuItem("Speichern");
		menuSpeichern.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent arg0) {

				speichern = new JFileChooser();
				speichern.showSaveDialog(null);

				int rueckgabeWert = speichern.showSaveDialog(null);

				if(rueckgabeWert == JFileChooser.APPROVE_OPTION){
					try{
						speichernText = eingabeArea.getText();
						FileWriter fw = new FileWriter(speichern.getSelectedFile()+".txt", true);
						fw.write(speichernText);
						fw.close();
					} catch (Exception ex){
						ex.printStackTrace();
					}
				}
			}
		});
		mnDatei.add(menuSpeichern);

		menuOeffnen = new JMenuItem("\u00D6ffnen");
		menuOeffnen.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {

				oeffnen = new JFileChooser();
				oeffnen.showOpenDialog(null);

				int rueckgabeWert = oeffnen.showOpenDialog(null);
				if (rueckgabeWert == JFileChooser.APPROVE_OPTION){

					File selectedFile = oeffnen.getSelectedFile();
					filename = selectedFile.getAbsolutePath();

					try{
						FileReader reader = new FileReader(filename);
						BufferedReader br = new BufferedReader(reader);
						eingabeArea.read(br, null);
						br.close();
					}
					catch (Exception exe)
					{
						System.out.println("Error");
					}
				}
			}
		});
		mnDatei.add(menuOeffnen);

		eingabeArea = new JTextArea();
		eingabeArea.setLineWrap(true);
		eingabeArea.setBounds(10, 32, 795, 575);
		contentPane.add(eingabeArea);
	}
}