Set JLabel Visible when clicking on JButton in actionPerformed

Question

I am trying to make JLabel appear when I click JButton. I added an action listener and added the component to the layout. I use label1.setVisible (true) when JButton is clicked in actionPerformed. I still can't get it to work. Can I have a look at my code?

public class LearnAppMain extends JFrame implements ActionListener { // Define variables public JButton button1; public JLabel label1; public JTextField field1; private Image image1; private String apple = "apple.jpg"; public LearnAppMain() { ImageIcon image1 = new ImageIcon(this.getClass().getResource(apple)); JLabel label1 = new JLabel(image1); button1 = new JButton("A"); button1.addActionListener(this); field1 = new JTextField(10); // Create layout setLayout(new FlowLayout()); // create Container final Container cn = getContentPane(); cn.add(button1); cn.add(field1); cn.add(label1); // setLayout(new FlowLayout()); setSize(250, 250); setLocationRelativeTo(null); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setVisible(true); } @Override public void actionPerformed(ActionEvent e) { Object source = e.getSource(); if (e.getSource() == button1) { label1.setVisible(true); field1.setText("Apple"); } } } 

I have my main method in another class file. The error I get leads me to label1.setVisible (true);

Every question I saw, they say to do this, but I wonder if there is anything else that needs to be added.

Answer 1

There were several problems:

• Your label1 was hidden by running the JLabel label in the constructor. You basically declared another label1 variable in your constructor, which hid it in the class itself.
• Your label was visible at startup - I used label.setVisible(false) for the test, but you might want otherwise

I also added the creation of Image aside, as I didn’t have an image, so uncomment this and change as needed.

Here's the full working version:

 import java.awt.*; import java.awt.event.*; import javax.swing.*; public class LearnAppMain extends JFrame implements ActionListener { // Define variables public JButton button1; public JLabel label1; public JTextField field1; private Image image1; private String apple = "apple.jpg"; public LearnAppMain() { //ImageIcon image1 = new ImageIcon(this.getClass().getResource(apple)); //JLabel label1 = new JLabel(image1); label1 = new JLabel("hello"); label1.setVisible(false); button1 = new JButton("A"); button1.addActionListener(this); field1 = new JTextField(10); // Create layout setLayout(new FlowLayout()); // create Container final Container cn = getContentPane(); cn.add(button1); cn.add(field1); cn.add(label1); // setLayout(new FlowLayout()); setSize(250, 250); setLocationRelativeTo(null); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setVisible(true); } @Override public void actionPerformed(ActionEvent e) { Object source = e.getSource(); if (e.getSource() == button1) { label1.setVisible(true); field1.setText("Apple"); } } public static void main(String[] args) { new LearnAppMain(); } } 

I would suggest using separate (usually inner classes) ActionListener instances instead of overriding actionPerformed . See this for a similar example if you are interested:

• http://docs.oracle.com/javase/tutorial/displayCode.html?code=http://docs.oracle.com/javase/tutorial/uiswing/examples/events/BeeperProject/src/events/Beeper.java

Also, if you are using this in a larger application (i.e., not just experimenting or prototyping), make sure that all Swing code is running on EDT.

You usually use SwingUtilities.invokeLater for this purpose.

Hope this helps.

Answer 2

at first you don't add the image first to JLabel.

just create an object and leave it as.

 ImageIcon image1 = new ImageIcon(this.getClass().getResource(apple)); JLabel label1 = new JLabel(""); label1.setVisible(true); 

then modify in the completed action public void actionPerformed (ActionEvent e) {

 if (e.getSource() == button1) { field1.seticon(image1); field1.revalidate(); } 

it definitely works

Answer 3

 clientDetail.addActionListener(new ActionListener(){ public void actionPerformed (ActionEvent e){ d.getContentPane().removeAll(); g = new GridBagLayout(); gc = new GridBagConstraints(); d.setLayout(g); JLabel message= new JLabel(" Message"); addComponent(message,5,1,1,2); JTextArea Message = new JTextArea(); addComponent(Message,5,1,1,2); d.setVisible(true); d.setVisible(true); d.pack(); } private void addComponent(Component component, int i, int i0, int i1, int i2) { gc.gridx=i; gc.gridy=i0; gc.gridheight=i1; gc.gridwidth=i2; g.setConstraints(component, gc); add(component); } }); Recep.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e){ } });