How can I change a .jpg icon image of an icon for a jLabel using Eclipse IDE?

[Dick Hammer]

I had done it successfully using Netbeans in this example:

https://coderanch.com/t/565811/GUI/java/Newbie-just-trying-change-icon

But now, I switched to Eclipse (using the WindowBuilder Pro plugin). It generates a method stub, which I filled with

JLabel lblJlabela = null;
lblJlabela.setIcon(new ImageIcon("J:\\Eclipse Folder\\Eclipse1GUI\\Photos\\Viper3.jpg"));

I had to add the first line of that because it was telling me that lblJlabela was "unresolved"...it auto-suggested that I do that. But here's the whole program.

import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;


public class FlashGUI {
	String[] CarorBike = null;
	JLabel[] labels; 

	private JFrame frame;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					FlashGUI window = new FlashGUI();
					window.frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the application.
	 */
	public FlashGUI() {
		initialize();
		JLabel lblJlabela = null, lblJlabelb = null;
		//labels = new JLabel[]{lblJlabela, lblJlabela, lblJlabelb};
	}

	/**
	 * Initialize the contents of the frame.
	 */
	private void initialize() {
		frame = new JFrame();
		frame.setBounds(100, 100, 562, 875);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().setLayout(null);
		
		JLabel lblJlabela = new JLabel("jLabelA");
		lblJlabela.addMouseListener(new MouseAdapter() {
			@Override
			public void mousePressed(MouseEvent e) {
				do_lblJlabela_mousePressed(e);
			}
		});
		lblJlabela.setIcon(new ImageIcon("J:\\Eclipse Folder\\Eclipse1GUI\\Photos\\Viper1.jpg"));
		lblJlabela.setBounds(57, 55, 462, 298);
		frame.getContentPane().add(lblJlabela);
		
		JLabel lblJlabelb = new JLabel("jLabelB");
		lblJlabelb.setIcon(new ImageIcon("J:\\Eclipse Folder\\Eclipse1GUI\\Photos\\Valkyrie1.jpg"));
		lblJlabelb.setBounds(42, 438, 448, 300);
		frame.getContentPane().add(lblJlabelb);
	}

	private void do_lblJlabela_mousePressed(MouseEvent e) {		
		JLabel lblJlabela = null;
		lblJlabela.setIcon(new ImageIcon("J:\\Eclipse Folder\\Eclipse1GUI\\Photos\\Viper3.jpg"));

	}
}

It runs and displays a jFrame with the two initial photos, but when I press my mouse over "LabelA", nothing happens. It gives these message in console:

at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)


How can I get it to work so that I change images in that jLabel?

[Daniel Croft]

Well right off the bat, at line 66 you're setting lblJlabela to null then trying to set an icon for it. This is obviously going to give you a null pointer exception. You want to make your jlabels into member variables of the class since you're accessing them from multiple functions; instead of declaring them in main, you should declare them at the top of your class where you declared frame.