import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;

import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.filechooser.FileNameExtensionFilter;

public class SpeichernUnterClass {

    public SpeichernUnterClass() {
        init();
    }
    
    private void init() {
        JFrame frame = new JFrame("Speichern unter Demo");
        JButton butt = new JButton("Speichern unter...");
        butt.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                saveAs(frame, null);
            }
        });
        frame.add(butt, BorderLayout.SOUTH);
        
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(400, 300);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    boolean saveAs(Component c, String pfad) {

        JFileChooser chooser;
        if (pfad == null)
            pfad = System.getProperty("user.home");
        File file = new File(pfad.trim());

        chooser = new JFileChooser(pfad);
        chooser.setDialogType(JFileChooser.SAVE_DIALOG);
        FileNameExtensionFilter plainFilter = new FileNameExtensionFilter(
                "Plaintext: txt, csv", "txt", "csv");
        FileNameExtensionFilter markUpFilter = new FileNameExtensionFilter(
                "Markup: xml, htm, html", "xml", "html", "htm");
        chooser.removeChoosableFileFilter(chooser.getAcceptAllFileFilter());
        chooser.setFileFilter(plainFilter);
        chooser.setFileFilter(markUpFilter);
        chooser.setDialogTitle("Speichern unter...");
        chooser.setVisible(true);

        // Speichern-Dialog anzeigen
        int result = chooser.showSaveDialog(c);

        // wenn 'speichern' nicht 'abbrechen' gewählt wurde
        if (result == JFileChooser.APPROVE_OPTION) {

            pfad = chooser.getSelectedFile().toString();
            file = new File(pfad);
            if (plainFilter.accept(file) || markUpFilter.accept(file))
                System.out.println(pfad + " kann gespeichert werden.");
            else
                System.out.println(pfad + " ist der falsche Dateityp.");

            chooser.setVisible(false);
            return true;
        }
        chooser.setVisible(false);
        return false;
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new SpeichernUnterClass());
    }
}