Java: mytextarea.setText(“hello”) + Thread.sleep(1000) = strange result

Question

I have something like this:

for(int i=0; i<5; i++){
    mytextarea.setText(\"hello \" + i);
    try{
        Thread.currentThread().sleep(1000); //to give         


        

Answer 1

While you code is waiting no events will be processed

http://java.sun.com/docs/books/tutorial/uiswing/concurrency/index.html

Read javadoc of javax.swing.SwingUtilities.invokeAndWait() and invokeLater() this may help

EDIT: Thanks to Jon and Samuel puting all ideas together:

public class Swing extends JPanel {
    JTextField textField;
    static JTextArea textArea;
    static int line = 1;

    public Swing() {
        super(new BorderLayout());
        textArea = new JTextArea(5, 20);
        add(textArea);
    }

    private static void createAndShowGUI() {
        JFrame frame = new JFrame("TextDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new Swing());
        frame.pack();
        frame.setVisible(true);

        ActionListener taskPerformer = new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                textArea.append("Hello " + line++ + "\n");
            }
        };
        if (line < 5) {
            new Timer(1000, taskPerformer).start();
        }
    }

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}