Getting null / empty JtextArea - swing

Question

I crated a Frame which have a panel inside it and the panel have a textarea inside it. Now i created a constructor which makes the frame visible for some time and after that it is set as invisible. Time for which it is visible it shows some massage.
When i run the constructor code inside the main method of outputDisplay class it shows the text massage
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.Timer;
public class OutputDisplay {
static JFrame frame;
JPanel panel;
JTextArea area;
Font font;
public void timer(int time){
Timer timer = new Timer(time, new ActionListener(){
public void actionPerformed(ActionEvent e){
frame.setVisible(false);
}
});
timer.start();
timer.setRepeats(false);
}
OutputDisplay(String ip,int time) throws InterruptedException{
frame = new JFrame("Warning");
frame.setLocation(400, 220);
panel = new JPanel();
area = new JTextArea();
font = new Font("Aharoni", Font.BOLD, 16);
area.setFont(font);
area.setForeground(Color.RED);
area.setSize(200, 200);
int j=0;
String[] t = {ip};
for(int i=0;i<t.length;i++){
area.append(t[i]+"\n");
}//for
panel.add(area);
panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));
frame.getContentPane().add(BorderLayout.CENTER, panel);
frame.pack();
frame.setSize(600, 200);
frame.setVisible(true);
Thread.sleep(time);
j++;
if(j==1){
frame.setVisible(false);
}//if
frame.setResizable(false);
}//constructor
OutputDisplay(String dialogue,String path,int time) throws InterruptedException{
frame = new JFrame("Warning");
frame.setLocation(400, 220);
panel = new JPanel();
area = new JTextArea();
font = new Font("Aharoni", Font.BOLD, 16);
area.setFont(font);
area.setForeground(Color.MAGENTA);
area.setSize(200, 200);
int j=0;
String[] t = {dialogue};
for(int i=0;i<t.length;i++){
area.append(t[i]+"\n");
}//for
panel.add(area);
panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));
frame.getContentPane().add(BorderLayout.CENTER, panel);
frame.pack();
frame.setSize(500, 200);
frame.setVisible(true);
Thread.sleep(time);
j++;
if(j==1){
frame.setVisible(false);
}//if
frame.setResizable(false);
}//constructor
OutputDisplay(String dialogue) throws InterruptedException{
frame = new JFrame("Report");
frame.setLocation(400, 220);
panel = new JPanel();
area = new JTextArea();
font = new Font("Aharoni", Font.BOLD, 16);
area.setFont(font);
area.setForeground(Color.BLUE);
area.setSize(200, 200);
String[] t = {dialogue};
for(int i=0;i<t.length;i++){
area.append(t[i]+"\n");
}//for
panel.add(area);
panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));
frame.getContentPane().add(BorderLayout.CENTER, panel);
frame.pack();
frame.setSize(600, 600);
frame.setVisible(true);
frame.setResizable(false);
}//constructor
public OutputDisplay() {
}//no arg
public void dialogue (String massage) throws InterruptedException{
frame = new JFrame("Massage");
frame.setLocation(400, 220);
JPanel panel = new JPanel();
JTextArea area = new JTextArea();
Font font = new Font("Aharoni", Font.BOLD, 16);
area.setFont(font);
area.setForeground(Color.GREEN);
area.setSize(200, 200);
int j=0;
String[] t = {massage};
for(int i=0;i<t.length;i++){
area.append(t[i]+"\n");
}//for
panel.add(area);
panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));
frame.getContentPane().add(BorderLayout.CENTER, panel);
frame.pack();
frame.setSize(400, 100);
frame.setVisible(true);
Thread.sleep(8*1000);
j++;
if(j==1){
frame.setVisible(false);
}//if
frame.setResizable(false);
}//dialogue
static void warningPopUp (String massage){
JOptionPane.showMessageDialog(null, massage);
}//dialogue
public static void main(String[] args){
new OutputDisplay("We are checking for account validation"+"\n"
+ "If user id and password matches then we will goto websites for updation. " +"\n"
+ "You will get a complete report once we are done", 4*1000);
}//main
}//OutputDisplay

Answer 1

Don't call Thread.sleep(...) on the Swing EDT as that just puts your whole GUI to sleep.
Do use a Swing Timer instead.
Do Google and search this site for similar questions.
Please check out Lesson: Concurrency in Swing
Also check out the Swing Tutorials
Edit
You're still using Thread.sleep, again you shouldn't use it, but instead should use a Timer. Also, never set a JTextArea's size or preferred size ever. Do this and the scrollbars of your JScrollPane won't work. Instead, set its rows and columns.
import java.awt.Color;
import java.awt.Font;
import java.awt.Dialog.ModalityType;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class TimeLimitedDialogTester {
private static final int EB_GAP = 25;
private JPanel mainPanel = new JPanel();
public TimeLimitedDialogTester() {
mainPanel.add(new JButton(new ShowDialogAction("Show Dialog")));
mainPanel.setBorder(BorderFactory.createEmptyBorder(EB_GAP, 2 * EB_GAP, 2 * EB_GAP, 2 * EB_GAP));
}
public JPanel getMainPanel() {
return mainPanel;
}
#SuppressWarnings("serial")
private class ShowDialogAction extends AbstractAction {
public ShowDialogAction(String name) {
super(name);
int mnemonic = (int) name.charAt(0);
putValue(MNEMONIC_KEY, mnemonic);
}
#Override
public void actionPerformed(ActionEvent e) {
Window mainWin = SwingUtilities.getWindowAncestor(mainPanel);
int seconds = 5;
String dialogTitle = "WARNING";
String text = "We are checking for account validation. If user id and password matches then we"
+ " will go to websites for updating. You will get a complete report once we are done.";
TimeLimitedDialog timeLimitedDialog = new TimeLimitedDialog(mainWin, seconds, dialogTitle, text);
timeLimitedDialog.dialogShow();
}
}
private static void createAndShowGui() {
TimeLimitedDialogTester timeLimitedDialog = new TimeLimitedDialogTester();
JFrame frame = new JFrame("TimeLimitedDialog");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(timeLimitedDialog.getMainPanel());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class TimeLimitedDialog {
private static final int ROWS = 6;
private static final int COLS = 30;
private static final Color FG = Color.green.darker().darker();
private JDialog dialog;
private JTextArea displayArea = new JTextArea(ROWS, COLS);
private int seconds;
public TimeLimitedDialog(Window mainWin, int seconds, String dialogTitle, String text) {
displayArea.setWrapStyleWord(true);
displayArea.setLineWrap(true);
displayArea.setFocusable(false);
displayArea.setText(text);
displayArea.setForeground(FG);
displayArea.setFont(displayArea.getFont().deriveFont(Font.BOLD));
this.seconds = seconds;
dialog = new JDialog(mainWin, dialogTitle, ModalityType.APPLICATION_MODAL);
dialog.add(new JScrollPane(displayArea));
dialog.pack();
dialog.setLocationRelativeTo(mainWin);
}
public void dialogShow() {
new Timer(seconds * 1000, new TimerListener()).start();
dialog.setVisible(true);
}
private class TimerListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
if (dialog != null && dialog.isVisible()) {
dialog.dispose();
}
((Timer) e.getSource()).stop();
}
}
}