Thread: need corection on java code

Hi :

I m working on java eclipse I want to move one selected item from list to texTarea but when I execute this code I have got following error :

PHP Code:


Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at listtest.testlist$3.actionPerformed(testlist.java:84)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source) 


here the whole code :

 
package listtest;
 
import java.awt.EventQueue;
 
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.ScrollPaneConstants;
import javax.swing.AbstractListModel;
import javax.swing.JButton;
import javax.swing.JTextArea;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
 
public class testlist {
 
	private JFrame frame;
 
 
	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					testlist window = new testlist();
					window.frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}
 
	/**
	 * Create the application.
	 */
	public testlist() {
		initialize();
	}
 
	/**
	 * Initialize the contents of the frame.
	 */
	private void initialize() {
		frame = new JFrame();
		frame.setBounds(100, 100, 490, 422);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().setLayout(null);
 
		JPanel panel = new JPanel();
		panel.setBounds(0, 0, 464, 384);
		frame.getContentPane().add(panel);
		panel.setLayout(null);
 
		JScrollPane scrollPane = new JScrollPane();
		scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
		scrollPane.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
		scrollPane.setBounds(121, 69, 77, 120);
		panel.add(scrollPane);
 
		final JList list = new JList();
		list.setModel(new AbstractListModel() {
			String[] values = new String[] {"1", "2", "3"};
			public int getSize() {
				return values.length;
			}
			public Object getElementAt(int index) {
				return values[index];
			}
		});
		scrollPane.setViewportView(list);
 
		JButton btnNewButton = new JButton("New button");
		btnNewButton.addActionListener(new ActionListener() {
 
 
			private JTextArea textArea;
 
			public void actionPerformed(ActionEvent arg0) {
 
				textArea.append((String) list.getSelectedValue());
			}
		});
		btnNewButton.setBounds(115, 216, 89, 23);
		panel.add(btnNewButton);
 
		JScrollPane scrollPane_1 = new JScrollPane();
		scrollPane_1.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
		scrollPane_1.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
		scrollPane_1.setBounds(128, 265, 73, 108);
		panel.add(scrollPane_1);
 
		JTextArea textArea = new JTextArea();
		scrollPane_1.setViewportView(textArea);
	}
}

thanks to correct me .

hi:

may be the problem in this lines :

final JList<?> list = new JList();
list.setModel(new AbstractListModel() {
String[] values = new String[] {"1", "2", "3"};
public int getSize() {
return values.length;
}
public Object getElementAt(int index) {
return values[index];
}
});

I have added bellow code but it always point to line 84 .

[QUOTE]

String data = "";

data = (String) list.getSelectedValue();

System.out.println(data);


[QUOTE]

in console mode only message error is printed

Hi :

if I remove this line it works but I need textarea

I can't find a solution

jlisttest2.PNG

thanks

hi:

I'm working on eclipse MARS.1

can you an example from your side .

the error still pending

thanks