ArrayList <String> cdcollection = new ArrayList();

private void initButtonActionPerformed(java.awt.event.ActionEvent evt) {
    Collections.addAll(cdcollection, "renier\n",  "mert\n", "rain\n", "mylen", "dreb\n"    );
    initButton.setEnabled(false);
}

private void displayButtonActionPerformed(java.awt.event.ActionEvent evt) {

    String title1 = "Original Order\n\n";
    String title2 = "Sorted Order\n\n";

    String collection = "";
    for (int i = 0; i < cdcollection.size(); i++)  {
        collection = collection + cdcollection.get(i);
    }
    mainTextArea.setText(title1 + collection);

    Collections.sort(cdcollection);

    for (int j = 0; j < cdcollection.size(); j++)  {
        mainTextArea.setText(title2 + collection.get(j));
    }
}

private void addButtonActionPerformed(java.awt.event.ActionEvent evt) {
    cdcollection.add(cdtitleInput.getText());
}

private void removeButtonActionPerformed(java.awt.event.ActionEvent evt) {
    cdcollection.remove(cdcollection.size()-1);
}

W tym wierszu mainTextArea.setText (title2 + collection.get (j)); Dostaję błąd „nie mogę znaleźć symbolu” i nie wyświetla się po uruchomieniu programu. Widzę tylko to:

Oryginał zamówienia

renier
mert
deszcz
mylen
dreb