清除JTextArea，设置新文本

Question

So I have this snippet of a software piece I'm writing.

Currently, this snippet outputs all the items I have in my ArrayList (cart).

JButton btnShowCart = new JButton("Show cart");
    btnShowCart.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {

            for (int i = 0; i < listWithItems.size(); i++) {
                txtBasket.setText(txtBasket.getText() + listWithItems.get(i)  + "\n" );     
            }

        }
    });

Whenever I click "show cart", I see what my list contains. That's perfect but I want it to clear the text before the JTextArea sets the text again from my ArrayList, otherwise I see the old text as well. Is that possible somehow? I tried repaint() but that did not do the trick. I also tried setText(""), but that just made me unable to show any text at all, even though I've tried putting the setText("") before/after I set the text from using my arraylist.

Answer 1

you should not call txtBasket.getText() in the loop since you'll get the previous text each time.

try something like this :

JButton btnShowCart = new JButton("Show cart");
    btnShowCart.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {

            String content = "";
            for (int i = 0; i < listWithItems.size(); i++) {
                content += listWithItems.get(i)  + "\n" ;     
            }
            txtBasket.setText(content);
        }
    });

Answer 2

If this is JAVA/SWING, maybe you need to call SwingUtilities like this:

String text = "";
for (int i = 0; i < listWithItems.size(); i++) {
        text += txtBasket.getText() + listWithItems.get(i)  + "\n";   
}
// update GUI    
SwingUtilities.invokeLater(new Runnable() {
        public void run() {
                statusLabel.setText(text);
        }
});