Develop Reference

How to use JButton to go to another java file (another class)

I have two java classes: Menu and PMotion. The Menu class contains a JButton as shown below. When this JButton is pressed, I want it to go to PMotion.java
How to achieve this?
Menu.java
public void actionPerformed(ActionEvent e) {
// Here I need to write the code which takes the user to PMotion.java
}

Here's a sample on how to open a new JFrame using a JButton.
JButton show = new JButton("show Form2");
show.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
PMotion pMotion = new PMotion();
pMotion.setVisibile(true); // Show pMotion form
Form1.this.setVisible(false); // Hide current form where Form1 is your current JFrame class
}
});

Clearing contents of TextField using setText does not work in AWT

I am having problems clearing contents of TextField in AWT using setText() method. Apparently, setText("") does not clear the contents of the TextField on pressing the 'Reset' button. Here's my program:
import java.awt.*;
import java.awt.event.*;
public class form extends Frame
{
Label lbl = new Label("Name:");
TextField tf = new TextField();
Button btn = new Button("Reset");
public form()
{
tf.setColumns(20);
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
btn.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
tf.setText(""); //Problem occurs here. This does not clear the contents of the text field on pressing the 'Reset' button.
}
});
add(lbl);
add(tf);
add(btn);
setLayout(new FlowLayout());
setSize(400,100);
setVisible(true);
setTitle("Form");
}
public static void main(String[] args)
{
new form();
}
}
Can someone please tell me where I went wrong or suggest an alternative? Thanks.

I see the problem as well using Java 8u11. I seem to remember this being filed as a known bug, but I can't seem to find it now.
A solution that works for me is to add an intermediate step:
public void actionPerformed(ActionEvent e) {
tf.setText(" ");
tf.setText("");
}
I'm not sure why this is necessary, I think it's a bug with the setText() function specifically ignoring empty Strings. If somebody finds the filed bug there would be more information there.

Add space in setText(" ") in function and see if it works. But there after there will be one space.

How to make a JButton do something

I have my JButton set up and everything but it does absolutely nothing. Could someone tell me how to add a command such as system.out.println or some Scanner commands to a JButton?
Here is my line of code. It is very simple and I'm just testing JButton to add it to some of my other programs
import javax.swing.*;
public class Swing extends JFrame {
JButton load = new JButton("Load");
JButton save = new JButton("Save");
JButton unsubscribe = new JButton("Unsubscribe");
public ButtonFrame() {
super ("ButtonFrame");
setSize(140, 170);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel pane = new JPanel();
pane.add(load);
pane.add(save);
pane.add(unsubscribe);
add(pane);
setVisible(true);
}
public static void main(String[] arguments) {
ButtonFrame bf = new ButtonFrame();
}
}

See How to Write an Action Listener.
I suggest you read the entire tutorial (or keep a link to it for reference) as it contains all the Swing basics.

Hope this helps
load.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
//Here goes the action (method) you want to execute when clicked
System.out.println("You clicked the button load");
}
});
//The same for save button
save.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
//Here goes the action (method) you want to execute when clicked
System.out.println("You clicked the button save");
}
});

How to open a JDialog

I am creating an application that has 1 JFrame java file and 1 JDialog java file.
In the JFrame, I have a button and when pressed I want it to display what I have designed in the JDialog.
So for example, my JFrame java file is called MMainView.java and my JDialog is called OptionView.java. So when the button in MMainView.java is pressed I want to display the JDialog I have designed in OptionView.java.
So in my MMainView.java file, I have a function that is called when that button is pressed. How do I display the dialog in OptionView.java?
SOLVED
For those wondering. This is what I did:
private JDialog optionView; ~~> JDialog Declaration
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
if (optionView == null) {
JFrame mainFrame = myApp.getApplication().getMainFrame();
optionView = new OptionView(mainFrame, true);
optionView.setLocationRelativeTo(mainFrame);
}
myApp.getApplication().show(optionView);
}

Sounds like you want to create an ActionListener for your button, and set the visibility of the JDialog to true when you press the button.
Something on these lines:
final JButton button = new JButton();
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent actionevent)
{
//set the visibility of the JDialog to true in here
}
});

Let's say your button is called myBtn.
The class should look like this.
public class MMainView extends JFrame
implements ActionListener
You should use a listener for the button.
JButton myBtn = new JButton();
myBtn.addActionListener(this);
And finally:
public void actionPerformed(ActionEvent e) {
if (e.getSource() == myBtn) {
new OptionView();
You don't really need the if, it's just in case you want to add more buttons for the actionPerformed.

First register the button in "MainView.java", like below.
b1.addActionListener(this);
b1.setName("OpenJDialog");
//this is to read in actionperformed method incase you have more than one button
// in action performed method call the dialogue class
public void actionPerformed(ActionEvent ae){
JButton jb = (JButton)ae.getSource();
String str = jb.getName();
if(str.equals("OpenJDialog"){
new OptionView();
//I am assuming u are configuring jdialog content in OptionView constructor
}
}

Java- How to add more textfields by clicking a button?

I have created a frame in Java which has some textfields and buttons in it. Assuming that user wants more textfields (for example to add more data), I want to put a button and when a user clicks the button, then a new textfield should appear. then user can fill data in it and again by clicking that button another textfield should appear.
How can I do this ? What code I need to write for the button to show more and more text fields by clicking button?
Thank you !

It would be wise that instead of adding components to your JFrame directly, you add them to a JPanel. Though related to your problem, have a look at this small example, hopefully might be able to give you some hint, else ask me what is out of bounds.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JFrameExample
{
private JFrame frame;
private JButton button;
private JTextField tfield;
private String nameTField;
private int count;
public JFrameExample()
{
nameTField = "tField";
count = 0;
}
private void displayGUI()
{
frame = new JFrame("JFrame Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridLayout(0, 1, 2, 2));
button = new JButton("Add JTextField");
button.addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent ae)
{
tfield = new JTextField();
tfield.setName(nameTField + count);
count++;
frame.add(tfield);
frame.revalidate(); // For JDK 1.7 or above.
//frame.getContentPane().revalidate(); // For JDK 1.6 or below.
frame.repaint();
}
});
frame.add(button);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
new JFrameExample().displayGUI();
}
});
}
}

Supposing that you have a main container called panel and a button variable button which is already added to panel, you can do:
// handle the button action event
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
// create the new text field
JTextField newTextField = new JTextField();
// add it to the container
panel.add(newTextField);
panel.validate();
panel.repaint();
}
});
When adding the new text field, you may need to mention some layout related characteristics, depending on the layout manager you are using (for instance if you use GridBagLayout, you will need to specify the constraints).