I have a Java program, in which, I'm using a JTextField, but if i don't specify a default size, it'll have the width 0. I'm inserting it in a BorderLayout, so how do I make it expand to fill the whole container?
In the above example, the text field will work fine. However, if you insert into EAST or WEST, it will not work.
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JTextField;
public class TextFieldTest {
public static void main(String[] args) {
JFrame f = new JFrame();
f.setLayout(new BorderLayout());
JTextField tf = new JTextField();
f.getContentPane().add(BorderLayout.EAST, tf);
f.pack();
f.setVisible(true);
}
}
My question back to you is: Does this need to be a BorderLayout or can you use other Layout Managers? If you can, you should check out GridBagLayout that you can have an element auto expand (using a weight) to fit the entire container.
Fill the whole container? With BorderLayout?
container.add( jTextField, BorderLayout.CENTER );
Simple as that.
When programming with Swing the key thing is to use a good layout manager. For me the perfect layout manager is MigLayout. This is simply the best one-stop solution to all layout needs. Their site provides excellent documentation and examples.
It will automatically fill to the width of the container, example shown:
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JTextField;
public class TextFieldTest {
public static void main(String[] args) {
JFrame f = new JFrame();
f.setLayout(new BorderLayout());
JTextField tf = new JTextField();
f.add(tf, BorderLayout.SOUTH);
f.pack();
f.setVisible(true);
}
}
Related
What's wrong? ImageIcon and the frame's size are working properly.
But the JTextField and the JButton aren't.
I need the solution.
import javax.swing.*;
import javax.swing.ImageIcon;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Frame {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setTitle("Alkalmazás");
frame.setVisible(true);
frame.setSize(500,500);
frame.setResizable(false);
JTextField field = new JTextField();
field.setBounds(40,250, 300,35);
JButton button = new JButton(new ImageIcon("table.png"));
button.setBounds(40,400, 250,25);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
tf.setText(""something);
}
});
frame.add(field);
frame.add(button);
}
}
You didn't mention what's "not working properly", but there are a few errors with your code:
Don't call your class Frame, it may confuse you or others about java.awt.Frame, something that may work would be MyFrame
Right now all your class is inside the main method and it's not placed inside the Event Dispatch Thread (EDT), to fix this, create an instance of your class and call a method createAndShowGUI (or whatever you want to name it) inside SwingUtilities.invokeLater()
For Example:
public static void main(String args[]) {
SwingUtilities.invokeLater(new MyFrame()::createAndShowGUI)
}
Or if using Java 7 or lower, use the code inside this answer in point #2.
setVisible(true) should be the last line in your code, otherwise you may find some visual glitches that may be resolved until you move your mouse above your window or something that triggers the call to repaint() of your components.
Instead of calling setSize(...) directly, you should override getPreferredSize(...) of your JPanel and then call pack() on your JFrame, see this question and the answers in it: Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing?
You're adding 2 components to the CENTER of BorderLayout, which is a JFrame's default layout manager, there are other layout managers and you can combine them to make complex GUI's.
setBounds(...) might mean that you're using null-layout, which might seem like the easiest way to create complex layouts, however you will find yourself in situations like this one if you take that approach, it's better to let Swing do the calculations for you while you use layout managers. For more, read: Why is it frowned upon to use a null layout in Swing?
With all the above tips now in mind, you may have a code similar to this one:
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class MyFrame {
private JFrame frame;
private JPanel pane;
private JTextField field;
private JButton button;
public static void main(String[] args) {
SwingUtilities.invokeLater(new MyFrame()::createAndShowGUI);
}
private void createAndShowGUI() {
frame = new JFrame("Alkalmazás");
pane = new JPanel() {
#Override
public Dimension getPreferredSize() {
return new Dimension(100, 100);
}
};
pane.setLayout(new BoxLayout(pane, BoxLayout.PAGE_AXIS));
field = new JTextField(10);
button = new JButton("Click me");
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
field.setText("something");
}
});
pane.add(field);
pane.add(button);
frame.add(pane);
frame.setResizable(false);
frame.pack();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Now you have an output similar to this one:
What about you want the JTextField to have a more "normal" size? Like this one:
You'll have to embed field inside another JPanel (with FlowLayout (the default layout manager of JPanel)), and then add that second JPanel to pane, I'm not writing the code for that as I'm leaving that as an exercise to you so you learn how to use multiple layout managers
I can't seem to find a solution online for why I'm getting this error on attempted run
I'm working on making a simple test system for a different program when are button press will yield value in a text box. I would like them to be on different lines to make it cleaner, so I looked into layouts. I decided a Box Layout would fit me best. I looked at different examples before attempting this and my code ended up looking like this, (apologies for the messy code)
Update
Got the box layout error to disappear but the code will not center them on the panel/frame. The label and button align left while the textfield becomes very large. I don't need it todo that
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import static javax.swing.BoxLayout.Y_AXIS;
import static javax.swing.SwingConstants.CENTER;
public class button extends JFrame {
static JFrame f;
static JButton b;
static JLabel l;
// main class
public static void main(String[] args)
{
// create a new frame to stor text field and button
f = new JFrame("panel");
BoxLayout layout = new BoxLayout(f, BoxLayout.Y_AXIS);
f.setLayout(layout);
// create a label to display text
l = new JLabel("panel label");
b = new JButton("button1");
JTextField textArea = new JTextField(5);
textArea.setEditable(false);
//textArea.append("Hello World");
// create a panel to add buttons
JPanel p = new JPanel();
// add buttons and textfield to panel
f.add(p);
f.setSize(300, 300);
p.add(l);
p.add(b);
p.setBackground(Color.white);
p.add(textArea);
f.show();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
Random r = new Random();
textArea.setText(String.valueOf(r));
}
});
}
}
Error
Exception in thread "main" java.awt.AWTError: BoxLayout can't be shared
at java.desktop/javax.swing.BoxLayout.checkContainer(BoxLayout.java:461)
at java.desktop/javax.swing.BoxLayout.invalidateLayout(BoxLayout.java:245)
at java.desktop/javax.swing.BoxLayout.addLayoutComponent(BoxLayout.java:278)
at java.desktop/java.awt.Container.addImpl(Container.java:1152)
at java.desktop/java.awt.Container.add(Container.java:1029)
at java.desktop/javax.swing.JFrame.addImpl(JFrame.java:553)
at java.desktop/java.awt.Container.add(Container.java:436)
at button.main(button.java:36)
I would like the three items to all to be stacked one on top of another with a space between them. The order doesn't matter right now.
Swing was first added to the JDK in 1998 and has undergone a lot of changes since. Unfortunately, when you read Web pages about Swing, it is not obvious when that page was last updated. Consequently you may be learning outdated techniques for writing Swing code.
First of all, according to the code you posted, class button does not need to extend class JFrame since you use a static variable as your application's JFrame. Also, JFrame is a top-level container which makes it a special kind of container and not the same kind of continer as a JPanel. You need to set the layout manager for your JPanel and then add the JLabel, JTextField and JButton to that JPanel. And then add the JPanel to the JFrame.
Calling method pack() of class JFrame will automatically set the preferred sizes for the components inside the JFrame. It appears in the code below.
Please also look at Java coding conventions which allows others to more easily read and understand your code. And note that, according to these conventions, I renamed your class from button to Buttons and also because there are already several class in the JDK named Button.
Here is my rewrite of your code...
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.WindowConstants;
public class Buttons implements Runnable {
public void run() {
createAndShowGui();
}
private void createAndShowGui() {
JFrame f = new JFrame("Box");
f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
JPanel p = new JPanel();
BoxLayout layout = new BoxLayout(p, BoxLayout.Y_AXIS);
p.setLayout(layout);
JLabel l = new JLabel("panel label");
JTextField textField = new JTextField(5);
JButton b = new JButton("button1");
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
Random r = new Random();
textField.setText(String.valueOf(r.nextBoolean()));
}
});
p.add(l);
p.add(textField);
p.add(b);
f.add(p);
f.pack();
f.setLocationByPlatform(true);
f.setVisible(true);
}
public static void main(String[] args) {
Buttons instance = new Buttons();
EventQueue.invokeLater(instance);
}
}
Here is my code snippet containing child JButton and JPanel objects but it's not working. And it's not showing any compilation errors in Eclipse.
import java.awt.FlowLayout;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
class gui extends JFrame implements ActionListener {
private JButton b;
private TextField c;
private JLabel l;
private String sn;
// Constructor for making framework
public gui() { setLayout(new FlowLayout());
JFrame f=new JFrame("Hello!");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
f.setSize(200,200);
f.setTitle("GUI");
b=new JButton("Click");
l=new JLabel("Enter Name");
c=new TextField("Enter..",10);
c.setEditable(true);
l.setBounds(20,20,20,20);
f.setBounds(10, 10, 10, 10);
b.addActionListener(this);
add(b);
add(f);
add(l);
add(c);
}
public static void main(String[] args) {
gui g=new gui();
g.setVisible(true);
} //main method
#Override
public void actionPerformed(ActionEvent e)
{
System.out.println("Working");
}
}
Your class "is a" GUI and then you also create a new JFrame, so you really have two frames in your code.
However the frame you make visible does not have any components added to it so all you see is the frame.
You then attempt to add components to your class the is a frame. However, you then have two problems:
you never make this frame visible and
Swing uses layout managers (you don't need to use setBounds(...)). By default it is using the BorderLayout. When you add components to the frame without specifying a constraint the components get added to the "CENTER". However, only one component can be displayed in the "CENTER" so only the last one added will ever be visible.
You also have other problems because you don't create the GUI on the Event Dispatch Thread. So there are really too many problems to correct.
I suggest you read the section from the Swing tutorial on How to Use BorderLayout for a working example of how to create a simple GUI. Then modify that code.
Your JFrame f=new JFrame("Hello!"); is not needed.
You need to use this which is already your JFrame like:
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
this.setSize(200,200);
this.setTitle("GUI");
Also remove: add(f); and f.setBounds(10, 10, 10, 10);
Because you already extend JFrame, you don't have to create a new JFrame.
Because now your class is a JFrame itself. That means that you can replace every usage of your f-JFrame by using this instead:
That way, also your other Components will be added correctly. Because at the moment you add b, f, i and c to the right JFrame.
So use this:
this.setVisible(true);
this.setSize(200,200);
this.setTitle("GUI");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
or even more simple:
setVisible(true);
setSize(200,200);
setTitle("GUI");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
I have two files, one is Main.java and the second is frame.java.
I'm creating a desktop application so I want to add scrollpane as needed vertically or horizontally in Main.java file.
Frame.java throws the JPanel object which is being catched by Main.java and dynamically loaded into JFrame.
So anyone please tell me, how can I add the scrollpane or scrollbar. Which is best, I don't know. Thank you..
Main.java:
package pack;
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main {
public static void main(String[] args) {
JPanel pn = null;
JFrame mainFrame = null;
frame login = new frame();
mainFrame = new JFrame("Prem");
mainFrame.setLayout(new BorderLayout());
mainFrame.setDefaultCloseOperation(mainFrame.EXIT_ON_CLOSE);
mainFrame.setSize(500,500);
mainFrame.setLocationRelativeTo(null);
pn=login.getLogin();
mainFrame.add(pn,BorderLayout.CENTER);
mainFrame.setVisible(true);
}
public Main() {
super();
}
}
This is second file which throws the panel object from method frame.java
package pack;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.AbstractAction;
import java.awt.*;
import java.awt.event.*;
public class frame {
JPanel pane = null,pane1=null;
JTextField userText=null,passText=null;
JLabel userLabel =null,passLabel=null,errorLabel=null;
JButton submitLogin = null;
public frame()
{
pane = new JPanel();
pane.setLayout(null);
}
public JPanel getLogin()
{
userLabel = new JLabel("UserName");
pane.add(userLabel);
userLabel.setBounds(5,10,100, 30);
userText = new JTextField();
pane.add(userText);
userText.setBounds(110,10,120,30);
passLabel = new JLabel("PassWord");
pane.add(passLabel);
passLabel.setBounds(5,60,100, 30);
passText = new JTextField();
pane.add(passText);
passText.setBounds(110,60,120,30);
errorLabel = new JLabel("");
pane.add(errorLabel);
errorLabel.setBounds(5,150,180,30);
submitLogin = new JButton("Submit");
pane.add(submitLogin);
submitLogin.setBounds(80,110,90,30);
submitLogin.addActionListener(new AbstractAction(){
public void actionPerformed(ActionEvent e)
{
if(submitLogin.getActionCommand() == "Submit")
{
if(userText.getText().isEmpty() || passText.getText().isEmpty())
{
errorLabel.setText("Enter UserName And Password");
}
else
{
//connection
}
}
else
{
System.exit(0);
}
}
});
return pane;
}
}
You have several issues with that code including:
You don't show us in your code where you're trying to use a JScrollPane or even where it's needed. If you show us your attempt to use this, we'll get a much better understanding of your problem.
You are using a null layout and setBounds(...), something you should avoid at almost all costs, and something which absolutely must be avoided if you want to use a JScrollPane, since JScrollPane's do not work well with null layouts. Instead read up on and use layout managers.
You're comparing Strings using the == operator. You don't want to compare Strings using ==. Use the equals(...) or the equalsIgnoreCase(...) method instead. Understand that == checks if the two objects are the same which is not what you're interested in. The methods on the other hand check if the two Strings have the same characters in the same order, and that's what matters here.
You can find links to the Swing tutorials and other Swing resources here: Swing Info
You can find the layout manager tutorial here: Layout Manager Tutorial.
You can learn about "nesting" layouts here.
You can find specific information on how to use JScrollPanes here: JScrollPane Tutorial.
The basic use of them is that you will want to add your scrollable component to the JScrollPane's viewport, and then add the JScrollPane to the GUI. The specifics of how to do this will all depend on your needs, something we don't yet know, but again is very well explained in the tutorials that I've linked to above.
Please see my image below at the link and then read below it for more details on my problem.
Imagine that is a Basic frame splited into two with a JSplitPane, by default when you resize your frame the gray part changes it's size, but I would like the white part to resize accordingly to the frame resizing.
Any help into the right direction would be appreciated as I am working on a project now and I am trying out all kind of weird stuff to be prepared for my biggest project set in the new year. :)
Regards
Theron
You need to use setResizeWeight to get the left and right take the extra space or reduce in size on JFrame resize, sample code below:
import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JSplitPane;
public class TestJSplitPane {
private void init(){
JFrame frame = new JFrame();
frame.setLayout(new BorderLayout());
JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT);
splitPane.setRightComponent(new JButton("Here I Am"));
splitPane.setLeftComponent(new JButton("Me Too"));
splitPane.setResizeWeight(0.5);
frame.add(splitPane, BorderLayout.CENTER);
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
public static void main(String[] args) {
new TestJSplitPane().init();
}
}
Java Doc for setResizeWeight.
Hope this helps.