Program should wait for pressed button

I found similar questions and concerning answers to this kind of problem but this was not helpful for me. My specific problem is: In the code below the program runs and goes directly to the last line “system.out.println(“to this point”)”. I want that it waits until one pressed the button (buttonsav) to choose some files. Then after successful done it should go to the last line System.out.println("to this Point"). Later these files are processed. The program cannot run without these files. So, how to let the program wait for buttonclick. I tried it with a while loop and boolean var, but I failed. Here is the code:

import java.awt.BorderLayout; import java.io.*; import java.awt.event.ActionListener; import java.awt.event.MouseListener; import java.awt.event.*; import javax.swing.*; import javax.swing.filechooser.FileFilter; import javax.swing.filechooser.FileNameExtensionFilter; import java.util.prefs.*; public class FileRead_3 extends JFrame {   Boolean filesAdded = false;   String path ="";   static  int status =0;       public FileRead_3()       {             }           public static void main(String[] args)       {                     FileRead_3 eval = new FileRead_3();   Preferences pref = Preferences.userRoot();        eval.path = pref.get("DEFAULT_PATH", "");               JFrame frame1 = new JFrame("BGMN-Auswertung-Optimierung");                 frame1.setDefaultCloseOperation(frame1.DISPOSE_ON_CLOSE);               frame1.setSize(1000, 800);                                               frame1.setLocationRelativeTo(null);                 JPanel panel1 = new JPanel();               BorderLayout bol = new BorderLayout(); //              MigLayout mlayout = new MigLayout("align 20% 20%","[][] [40]", "[]40[]"); //               panel1.setLayout(mlayout);                     JButton buttonsav   = new JButton("open sav files");               JButton buttonlst   = new JButton("open lst files");                         eval.filesAdded=false;                         System.out.println("filesaddedbefore "+eval.filesAdded);     //          while(eval.filesAdded != false)       //        {                            buttonsav.addActionListener(new ActionListener(){                  public void actionPerformed(ActionEvent e){                                    eval.filesAdded = true;                       // Code to run after button is pressed.                                           System.out.println("Hello sav-world");                    JOptionPane.showMessageDialog(frame1,  " Choose sav-File!");                                        JFileChooser chooser_sav = new JFileChooser();  // 1907                      chooser_sav.setCurrentDirectory(new File(eval.path));                    FileFilter sav_filter    = new FileNameExtensionFilter("txt-files", ".txt", ".sav","SAV");                    chooser_sav.addChoosableFileFilter(sav_filter);                    chooser_sav.setFileFilter(sav_filter);  // 20.07.2016                                        chooser_sav.setMultiSelectionEnabled(true);                 // nicht nur eine File wählen                    status = chooser_sav.showOpenDialog(null); //18.11.2016                                       } // action performed               }); //action listener                //  eval.filesAdded = true;  //             } // ende while                             panel1.add(buttonsav);                             panel1.add(buttonlst);               frame1.getContentPane().add(panel1);               frame1.setVisible(true);               System.out.println("goes to this point");       } }

stefanie ohm wrote:I found similar questions and concerning answers to this kind of problem but this was not helpful for me. My specific problem is: In the code below the program runs and goes directly to the last line “system.out.println(“to this point”)”.

That's how Swing (and AWT) works. When you show a frame (by calling setVisible(true)), this does not block the current thread - it just continues. (Note that modal dialogs, like the file chooser dialog, will block the current thread, but no other windows will.)

I want that it waits until one pressed the button (buttonsav) to choose some files. Then after successful done it should go to the last line System.out.println("to this Point"). Later these files are processed. The program cannot run without these files. So, how to let the program wait for buttonclick.

That's what the button's action listeners are for (there can be multiple). Move the println statement inside your action listener code, like Swastik has shown.

Thanks, in principle yes this works. I have got a much larger code with additional buttons to be pressed before to proceed.
From the remarks I see the whole has something to do with threads. I am not familiar with that topic. In VB we have shown_form() where
you can do everything when the window becomes visible. I do not think that we have got something equivalent in Java.
Is it possible to stop the thread which goes to system.out.println...(go to system.out.println...) ?

stefanie ohm wrote:In VB we have shown_form() where
you can do everything when the window becomes visible. I do not think that we have got something equivalent in Java.

It's there, and it uses the same principle as VB does - using event handlers. The thing is, in Java you have to attach event listeners to user interface objects. In this case it would be a java.awt.event.WindowListener (windowOpened), or possibly a java.awt.event.ComponentListener (componentShown).

Is it possible to stop the thread which goes to system.out.println...(go to system.out.println...) ?

Like I said, in AWT and Swing, all code in the main method, as well as in event handlers, will continue to run until either the method ends, or until a modal dialog is shown (e.g. using JOptionPane). In case of a modal dialog, the method will continue as soon as the modal dialog is disposed (closed).

Well, when I understand it correctly the problem cannot be solved or ?

stefanie ohm wrote:Thanks, in principle yes this works. I have got a much larger code with additional buttons to be pressed before to proceed.
From the remarks I see the whole has something to do with threads. I am not familiar with that topic. In VB we have shown_form() where
you can do everything when the window becomes visible. I do not think that we have got something equivalent in Java.
Is it possible to stop the thread which goes to system.out.println...(go to system.out.println...) ?

Hi, Stephanie, please take a look at SwingWorker class for Java Swing.

With best regards,

Anton.