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POAppending text to a JTextArea on button press?
 

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  1. POAppending text to a JTextArea on button press?
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    <p>I've got a simple Swing GUI and I want to add a new line of text to a JTextArea after a button is pressed, simple right?</p> <p>The Button and it's ActionListener function correctly (printing stuff to the console works fine), but when I use .append()or .setText() to add text to the textarea, I get a nullpointer exception.</p> <p>As always, code it below. Any input would be greatly appreciated, thanks!!!</p> <pre><code>import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.*; import javax.swing.border.LineBorder; public class GUI extends JFrame implements ActionListener { private JFrame frame; private JLabel paneHeader; public JTextArea ipArea, portArea, outputLog, orderLog, cookLog; private JButton newServer; public String ipAddress, portNumber, cashierName, cookName; public GUI() { initGUI(); } public void initGUI() { frame = new JFrame("Restaurant Overview"); Container contentPane = frame.getContentPane(); JLabel paneHeader = new JLabel("Restaurant Monitoring System"); paneHeader.setBounds(200, 0, 200, 25); paneHeader.setFont(new Font("Calibri", Font.BOLD, 14)); JLabel ipLabel = new JLabel("IP Address: "); ipLabel.setBounds(25, 30, 75, 20); ipLabel.setFont(new Font("Calibri", Font.PLAIN, 12)); final JTextArea ipArea = new JTextArea(); ipArea.setBorder(new LineBorder(Color.GRAY)); ipArea.setBounds(105, 30, 100, 20); JLabel portLabel = new JLabel("Port Number: "); portLabel.setBounds(25, 55, 75, 20); portLabel.setFont(new Font("Calibri", Font.PLAIN, 12)); final JTextArea portArea = new JTextArea(); portArea.setBorder(new LineBorder(Color.GRAY)); portArea.setBounds(105, 55, 100, 20); JButton newServer = new JButton("Create new Server"); newServer.setBorder(new LineBorder(Color.GRAY)); newServer.setBounds(250, 30, 150, 40); newServer.setActionCommand("createserver"); newServer.addActionListener(this); JTextArea outputLog = new JTextArea(" "); outputLog.setBorder(new LineBorder(Color.GRAY)); outputLog.setBounds(25, 90, 150, 150); //outputLog.setEditable(false); JTextArea cashierLog = new JTextArea(); cashierLog.setBorder(new LineBorder(Color.GRAY)); cashierLog.setBounds(185, 90, 150, 150); //cashierLog.setEditable(false); JTextArea cookLog = new JTextArea(); cookLog.setBorder(new LineBorder(Color.GRAY)); cookLog.setBounds(345, 90, 150, 150); //cookLog.setEditable(false); contentPane.add(paneHeader); contentPane.add(ipLabel); contentPane.add(ipArea); contentPane.add(portLabel); contentPane.add(portArea); contentPane.add(outputLog); contentPane.add(cashierLog); contentPane.add(cookLog); contentPane.add(newServer); frame.setLayout(null); frame.pack(); frame.setSize(600,400); frame.setVisible(true); } public void test() { //ipAddress = ipArea.getText() + "\n"; //portNumber = portArea.getText() + "\n"; String text = "lemons"; //System.out.println(text); outputLog.append(text); //outputLog.append(portNumber); } public void actionPerformed(ActionEvent e) { if ("createserver".equals(e.getActionCommand())) { //test(); outputLog.append("lemons"); } else { //Do Nothing } } } </code></pre>
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    1. COYou should also post your stack trace
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