Develop Reference

JTextArea parameter and user input issues

I have a JTextArea where I want to allow the user to input any number of strings up to 100 but it could be less. When I set the JTextArea as I have in my code below where it is commented out (i.e. //tfResult= new JTextArea(10, 0);) and the user inputs ten lines of strings then my code runs exactly as expected and prints out what I need it to.
But if I try to input more of less lines I get
java.lang.ArrayIndexOutOfBoundsException
followed by the number of lines of user input, whether I have it declared with no bounds or as I have it commented out.
I am new to graphics in java and I can't figure out why this is happening and I have searched everywhere for answers. Do I have the bounds set wrong or have I declared the JTextArea wrong?
I also am trying to include a JScrollPane but I am having issues with that also as its not showing up.
I would really appreciate any help as I am struggling to solve this issue.
class Window {
JFrame windowFrame;
Panel bottomPanel;
JScrollPane scroll;
JTextArea tfResult;
Button btnPlayAgain;
Font font;
Window(int width, int height, String title)
{
windowFrame = new JFrame();
windowFrame.setTitle(title);
windowFrame.setBounds(0,0,width,height);
windowFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
windowFrame.setResizable(true);
windowFrame.setCursor(new Cursor(Cursor.HAND_CURSOR)); // setting cursor to hand
windowFrame.setLayout(null);
createBottomPanel();
windowFrame.add(bottomPanel);
//windowFrame.add(field.getCanvas());
windowFrame.setVisible(true);
}
private void createBottomPanel()
{
JButton b = new JButton("Compute");
bottomPanel = new Panel();
bottomPanel.setBackground(Color.PINK);
bottomPanel.setBounds(0,400,800,140);
bottomPanel.setLayout(null);
//*********
//tfResult= new JTextArea(10, 0);
tfResult= new JTextArea();
tfResult.setBounds(10,10,600,100);
tfResult.setFont(new Font("SansSerif", Font.BOLD, 16));
tfResult.setFocusable(true);
scroll = new JScrollPane(tfResult);
scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
btnPlayAgain = new Button("Compute");
btnPlayAgain.setBounds(620,10,150,100);
btnPlayAgain.setBackground(Color.RED);
btnPlayAgain.setFont(new Font("SansSerif", Font.BOLD, 24));
btnPlayAgain.setFocusable(true);
bottomPanel.add(tfResult);
bottomPanel.add(btnPlayAgain);
bottomPanel.add(b);
bottomPanel.add(scroll);
tfResult.setVisible(true);
scroll.setVisible(true);
btnPlayAgain.setVisible(true);
bottomPanel.setVisible(true);
btnPlayAgain.addActionListener(new ActionListener()
{
//#Override
public void actionPerformed(ActionEvent e)
{
//should include the code to genrate the output inside here
String input = tfResult.getText();
Mat xy;
xy = new Mat();
//String output = xy.getOutput(input).toString();
String output = xy.getOutput(input);
//String output = Output(input);
tfTarget.setText(output);
}
});
}
}

I went ahead and created the following GUI that allows you to enter data with a JTextArea.
The first thing I did was start my Swing application with a call to the SwingUtilities invokeLater method. This method ensures that the Swing components are created and executed on the Event Dispatch Thread.
Next, I created a JFrame. Then I created a JPanel with a BorderLayout. The JTextArea is inside of a JScrollPane, which is then placed inside of the center of a JPanel.
The JButton is placed after the last line of the JPanel.
Here's the complete runnable code, otherwise known as a minimal runnable example.
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class JTextAreaInputGUI implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new JTextAreaInputGUI());
}
private JTextArea textArea;
#Override
public void run() {
JFrame frame = new JFrame("JTextArea Input GUI");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createMainPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createMainPanel() {
JPanel panel = new JPanel(new BorderLayout());
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
textArea = new JTextArea(10, 40);
JScrollPane scrollPane = new JScrollPane(textArea);
panel.add(scrollPane, BorderLayout.CENTER);
JButton button = new JButton("Submit");
button.addActionListener(new ButtonListener());
panel.add(button, BorderLayout.AFTER_LAST_LINE);
return panel;
}
public class ButtonListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent event) {
System.out.println(textArea.getText().trim());
}
}
}

How to make my user-interface self adapt to the show and hide of JPanel?

Recently I'm writing a mail system client using Java (I chose swing to write the GUI and use IDEA to hardcode my GUI). In the Compose module, I want to show or hide the textfield for CC and Bcc when I click the corresponding buttons.
So I googled and browsed the following questions and doc on the web:
How to make JPanel scrollable in Java?
How to make JPanel scrollable?
Scrolling a JPanel
Doc: JScrollPane
Finally, I chose the JScrollPane to implement it.
My simplified sample code is as follows (the original code is tedious):
import java.awt.CardLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class Demo extends JFrame implements ActionListener {
private static final long serialVersionUID = 1L;
private JLabel lbl1;
private JTextField txf1;
private JLabel lbl2;
private JTextField txf2;
// container for lbl2 and txf2, which should be able to be shown or hidden
private JPanel pnlContainer2;
private JLabel lbl3;
private JTextField txf3;
// container for lbl3 and txf3
private JPanel pnlContainer3;
private JButton btnShow;
// the container I want to move when I click btnShow
private JPanel pnlBody;
// the panel to hold my "cards"
// In this example, I include it just to show what controls are on my interface.
private JPanel pnlContent;
private JPanel pnlContainer;
// here, I want to use JScrollPane to make my pnlContainer scrollable
// to adapt to my interface
private JScrollPane scrollPane;
public Demo() {
init();
}
private void init() {
pnlContainer = new JPanel(new CardLayout(), true);
pnlContainer.setBounds(0, 0, 200, 180);
pnlContent = new JPanel(null, true);
pnlContent.setBounds(0, 0, 200, 180 + 50);
scrollPane = new JScrollPane(pnlContent, ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
scrollPane.setBounds(0, 0, 200, 180);
pnlContainer.add(scrollPane);
pnlBody = new JPanel(null, true);
lbl1 = new JLabel("lbl1");
lbl1.setBounds(10, 20, 40, 30);
txf1 = new JTextField();
txf1.setBounds(60, 20, 120, 30);
pnlContent.add(lbl1);
pnlContent.add(txf1);
pnlContainer2 = new JPanel(null, true);
pnlContainer2.setBounds(0, 70, 180, 30);
lbl2 = new JLabel("lbl2");
lbl2.setBounds(10, 0, 40, 30);
txf2 = new JTextField();
txf2.setBounds(60, 0, 120, 30);
pnlContainer2.add(lbl2);
pnlContainer2.add(txf2);
pnlContainer2.setVisible(false);
pnlContent.add(pnlContainer2);
pnlBody = new JPanel(null, true);
pnlBody.setBounds(0, 70, 180, 90);
pnlContainer3 = new JPanel(null, true);
pnlContainer3.setBounds(0, 0, 180, 30);
pnlBody.add(pnlContainer3);
lbl3 = new JLabel("lbl3");
lbl3.setBounds(10, 0, 40, 30);
txf3 = new JTextField();
txf3.setBounds(60, 0, 120, 30);
pnlContainer3.add(lbl3);
pnlContainer3.add(txf3);
btnShow = new JButton("show");
btnShow.setBounds(60, 50, 80, 30);
btnShow.addActionListener(this);
pnlBody.add(btnShow);
pnlContent.add(pnlBody);
this.add(pnlContainer);
this.setLayout(null);
this.setTitle("Demo");
this.setSize(200, 200);
this.setLocationRelativeTo(null);
this.setVisible(true);
this.setResizable(false);
// ImageIcon icon = new ImageIcon("E:\\Javarepo\\Hmail\\src\\main\\resources\\assets\\hmail.png");
// this.setIconImage(icon.getImage());
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
#Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
Object src = e.getSource();
if (src instanceof JButton) {
JButton btn = (JButton) src;
boolean showSelected = false;
String altText;
if (btn == btnShow) {
showSelected = btnShow.getText() == "show";
altText = showSelected ? "hide" : "show";
btnShow.setText(altText);
}
relayout(showSelected);
}
}
private void relayout(boolean showSelected) {
int x = pnlBody.getX();
int y = pnlBody.getY();
if (showSelected) {
pnlContainer2.setVisible(true);
pnlBody.setBounds(x, y + 50, 180, 90);
} else {
pnlContainer2.setVisible(false);
pnlBody.setBounds(x, y - 50, 180, 90);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> new Demo());
}
}
However, no matter which JPanel I apply JScrollPane to, I cannot make my interface adaptive to the hide and show of my JContainer2.
How can I modify it, or what control to use to replace JScrollPane? Any suggestions will be welcome.
And here is my platform information:
java -version
java version "1.8.0_212"
Java(TM) SE Runtime Environment (build 1.8.0_212-b10)
Java HotSpot(TM) 64-Bit Server VM (build 25.212-b10, mixed mode)
OS: win10 1909
arch: amd64

I rewrote your code. Explanations appear after it.
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
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.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.ScrollPaneConstants;
import javax.swing.WindowConstants;
public class Demo2 implements ActionListener, Runnable {
private static final String HIDE = "HIDE";
private static final String SHOW = "SHOW";
private JButton button;
private JLabel lbl2;
private JFrame frame;
private JTextField txf2;
#Override
public void run() {
showGui();
}
#Override
public void actionPerformed(ActionEvent event) {
boolean visible;
String text;
String actionCommand = event.getActionCommand();
switch (actionCommand) {
case HIDE:
text = SHOW;
visible = false;
break;
case SHOW:
text = HIDE;
visible = true;
break;
default:
text = "???";
visible = false;
}
button.setText(text);
lbl2.setVisible(visible);
txf2.setVisible(visible);
}
private JPanel createButtonsPanel() {
JPanel buttonsPanel = new JPanel();
button = new JButton(SHOW);
button.addActionListener(this);
buttonsPanel.add(button);
return buttonsPanel;
}
private JScrollPane createForm() {
JPanel form = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
JLabel lbl1 = new JLabel("lbl1");
form.add(lbl1, gbc);
gbc.gridx = 1;
JTextField txf1 = new JTextField(6);
form.add(txf1, gbc);
gbc.gridx = 0;
gbc.gridy = 1;
lbl2 = new JLabel("lbl2");
lbl2.setVisible(false);
form.add(lbl2, gbc);
gbc.gridx = 1;
txf2 = new JTextField(6);
txf2.setVisible(false);
form.add(txf2, gbc);
gbc.gridx = 0;
gbc.gridy = 2;
JLabel lbl3 = new JLabel("lbl3");
form.add(lbl3, gbc);
gbc.gridx = 1;
JTextField txf3 = new JTextField(6);
form.add(txf3, gbc);
return new JScrollPane(form,
ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
}
private void showGui() {
frame = new JFrame("Demo");
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setResizable(false);
frame.add(createForm(), BorderLayout.CENTER);
frame.add(createButtonsPanel(), BorderLayout.PAGE_END);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
/**
* Start here.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Demo2());
}
}
You should always try to use a layout manager. The code above uses GridBagLayout but there are several other layout managers that are good at handling forms, including GroupLayout and SpringLayout as well as third party layout managers like MiG Layout and FormLayout.
In order to "show" and "hide" the middle row in your form, simply set the visible property to true or false. If the text of the button is SHOW, then when the user clicks on it, I change the button text to HIDE and make lbl2 and txf2 both visible. If the button text is HIDE, then when the user clicks the button I change the text to SHOW and make lbl2 and txf2 not visible.
Because I use a layout manager, it handles resizing the JPanel whenever the contents of the JPanel are changed. When you don't use a layout manager, then you have to write code that handles the resizing and of-course your code does not, hence your problem.

Java: Overlay an Image with Transparent JButton

So I'm creating a GUI that represents a vending machine. I'm just running into some problems trying to get the layout to work the way I want it. My thought was to insert an image into a JLabel, and then overlay that image with transparent JButtons in specific locations so that when you click on the image in certain locations, it will trigger the JButton. I haven't gotten to the transparency yet as I'm currently stuck on how to get the JButtons precisely where they need to be.
I've tried setLocation and setBounds with no luck. Any help on how to exactly position the jbuttons over the possible vending machine choices would be great.
import javax.swing.*;
import javax.imageio.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
public class vendMachine extends JFrame
{
//Frame Dimensions
private static final int FRAME_HEIGHT = 800;
private static final int FRAME_WIDTH = 800;
private JPanel totalGUI, imagePanel, coinPanel;
public vendMachine()
{
createComponents();
setSize(FRAME_WIDTH, FRAME_HEIGHT);
setTitle("Vending Machine");
}
private void createComponents()
{
try
{
BufferedImage machineImg = ImageIO.read(new File("images/pepsivend.jpg"));
JLabel machineImgLabel = new JLabel(new ImageIcon(machineImg));
machineImgLabel.setLayout(new FlowLayout());
JButton test = new JButton("TEST BUTTON");
machineImgLabel.add(test);
//test.setBounds(0,0,0,0);
ImageIcon pennyIcon = new ImageIcon("images/coins/penny.jpg");
JButton pennyButton = new JButton(pennyIcon);
ImageIcon nickelIcon = new ImageIcon("images/coins/nickel.jpg");
JButton nickelButton = new JButton(nickelIcon);
ImageIcon dimeIcon = new ImageIcon("images/coins/dime.jpg");
JButton dimeButton = new JButton(dimeIcon);
ImageIcon quarterIcon = new ImageIcon("images/coins/quarter.jpg");
JButton quarterButton = new JButton(quarterIcon);
coinPanel = new JPanel();
coinPanel.setLayout(new GridLayout(4,1));
coinPanel.add(pennyButton);
coinPanel.add(nickelButton);
coinPanel.add(dimeButton);
coinPanel.add(quarterButton);
totalGUI = new JPanel();
totalGUI.setLayout(new BorderLayout());
totalGUI.add(machineImgLabel, BorderLayout.CENTER);
totalGUI.add(coinPanel, BorderLayout.EAST);
}
catch (IOException e)
{
e.printStackTrace();
}
add(totalGUI);
}
}
In the above Image I would like some help on how to get the test button, to overlay on top of the pepsi selection. From there I can go about making it transparent and removing the borders and text.
Edited to add: none of the buttons do anything yet. Simply trying to get the layout going before adding in anything else

It's unclear as to what your actually problem, however, I'll start with the layout...
No single layout will ever do everything you want, some times, you'll need to use multiple layouts and compound them. This example uses a BorderLayout and a GridBagLayout to set up the basic layout...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new VendingMachinePane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class VendingMachinePane extends JPanel {
public VendingMachinePane() {
setLayout(new BorderLayout());
JLabel label = new JLabel("Cover");
// Demonstration purpose only
label.setPreferredSize(new Dimension(200, 400));
label.setOpaque(true);
label.setBackground(Color.BLUE);
add(label);
JPanel optionsPane = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.weightx = 1;
gbc.gridwidth = GridBagConstraints.REMAINDER;
gbc.anchor = GridBagConstraints.NORTH;
optionsPane.setBackground(Color.DARK_GRAY);
optionsPane.add(new JLabel("Coin Slot"), gbc);
optionsPane.add(makeButton("Pepsi"), gbc);
optionsPane.add(makeButton("Diet Pepsi"), gbc);
optionsPane.add(makeButton("Slice"), gbc);
optionsPane.add(makeButton("Dr Pepper"), gbc);
optionsPane.add(makeButton("Lipton"), gbc);
optionsPane.add(makeButton("Mountain Dew"), gbc);
optionsPane.add(makeButton("Schweppes"), gbc);
gbc.weighty = 1;
optionsPane.add(makeButton("Pepsi"), gbc);
add(optionsPane, BorderLayout.LINE_END);
}
protected JButton makeButton(String text) {
JButton btn = new JButton(text);
btn.setBorderPainted(false);
btn.setContentAreaFilled(false);
btn.setMargin(new Insets(4, 4, 4, 4));
btn.setOpaque(false);
return btn;
}
}
}
As to your "overlay buttons" issue, to me, that doesn't make sense, since a JButton has a icon property, why not just use a JButton to start with?
You make buttons transparent simply by changing their borderPainted contentAreaFilled and opaque properties
// You can pass a `Icon` instead of a `String` to the constructor
JButton btn = new JButton(text);
btn.setBorderPainted(false);
btn.setContentAreaFilled(false);
btn.setMargin(new Insets(4, 4, 4, 4));
btn.setOpaque(false);
Don't forget to setup an ActionListener ;)
Updated, based on the updated requirements...
You Could...
Break the image down in segments, making each element it's own image and simply applying those to the buttons, using a similar approach above
You Could...
Map hot spots on the image, and using a MouseListener monitor where the mouseClicked events occur - you do lose the advantage of keyboard input though
You Could...
Map out the hot spots of the image and using a GridBagLayout or custom layout manager, map the buttons onto the image.

JScrollBar setValue not working when a dialog not visible

Here is my simple example:
import java.awt.BorderLayout;
import java.awt.Dialog;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.util.ArrayList;
import java.util.Enumeration;
import javax.swing.AbstractButton;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JScrollPane;
import javax.swing.JRadioButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class SelectItem extends JDialog {
private static final long serialVersionUID = 1L;
private final JPanel contentPanel = new JPanel();
private String item;
private ButtonGroup group;
/**
* Launch the application.
*/
public static void main(String[] args) {
final JFrame frame = new JFrame();
frame.setBounds(100, 100, 133, 102);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(new BorderLayout(0, 0));
JButton btnSelectItem = new JButton("select item");
btnSelectItem.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
ArrayList<String> items = new ArrayList<String>();
for (char c = 'A'; c <= 'Z'; c++)
items.add(String.valueOf(c));
SelectItem dialog = new SelectItem(frame, items, items.get(20));
System.out.println("Item = " + dialog.showChooseDialog());
}
});
frame.getContentPane().add(btnSelectItem);
frame.setVisible(true);
}
public String showChooseDialog(){
setVisible(true);
return item;
}
/**
* Create the dialog.
*/
public SelectItem(JFrame parent, ArrayList<String> items, String selectedItem) {
super(parent, null, Dialog.ModalityType.DOCUMENT_MODAL);
setTitle("Select Item");
setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
setBounds(100, 100, 450, 300);
getContentPane().setLayout(new BorderLayout());
contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
getContentPane().add(contentPanel, BorderLayout.CENTER);
contentPanel.setLayout(null);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setBounds(0, 0, 434, 228);
contentPanel.add(scrollPane);
JPanel panel = new JPanel();
scrollPane.setViewportView(panel);
panel.setLayout(null);
int marginX = 6;
int currentY = 7;
int width = 420;
int height = 23;
int paddingY = 26;
int scrollY = 0;
group = new ButtonGroup();
for (String str: items){
JRadioButton rd = new JRadioButton(str);
rd.setBounds(marginX, currentY, width, height);
currentY = currentY + paddingY;
panel.add(rd);
group.add(rd);
if (str == selectedItem){ //or str.equals()...
group.setSelected(rd.getModel(), true);
//scrollY = rd.getY() - height/2 - scrollPane.getHeight()/2;
scrollY = rd.getY() + height/2 - scrollPane.getHeight()/2;
}
}
System.out.println("ScrollY: " + scrollY);
Dimension size = panel.getPreferredSize();
size.setSize(size.getWidth(), currentY);
panel.setPreferredSize(size);
//this.setVisible(true);
scrollPane.getVerticalScrollBar().setValue(scrollY);
panel.repaint();
panel.revalidate();
scrollPane.getVerticalScrollBar().repaint();
scrollPane.getVerticalScrollBar().revalidate();
scrollPane.repaint();
scrollPane.revalidate();
this.repaint();
this.revalidate();
{
JPanel buttonPane = new JPanel();
buttonPane.setLayout(new FlowLayout(FlowLayout.RIGHT));
getContentPane().add(buttonPane, BorderLayout.SOUTH);
{
JButton okButton = new JButton("OK");
okButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
Enumeration<AbstractButton> iter = group.getElements();
while (iter.hasMoreElements()){
AbstractButton rd = iter.nextElement();
if (group.isSelected(rd.getModel())){
item = rd.getActionCommand();
break;
}
}
//System.out.println(group.getSelection().getActionCommand());
setVisible(false);
dispose();
}
});
okButton.setActionCommand("OK");
buttonPane.add(okButton);
getRootPane().setDefaultButton(okButton);
}
{
JButton cancelButton = new JButton("Cancel");
cancelButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
item = null;
setVisible(false);
dispose();
}
});
cancelButton.setActionCommand("Cancel");
buttonPane.add(cancelButton);
}
}
}
}
I create a list of String and then pass it to a JDialog constructor with a default string value, or selectedItem as in my code.
This dialog will display all item of the list and let the user choose one.
This is done by using JRadioButton, and the JRadioButton object with it value equals to default value will be selected by default.
Everything work fine. But I want to scroll the panel to that radio-button automatically when a dialog is open, that radio-button will be in middle of vertical alignment
Like this:
.
if (str == selectedItem){ //or str.equals()...
group.setSelected(rd.getModel(), true);
scrollY = rd.getY() + height/2 - scrollPane.getHeight()/2;
}
...
scrollPane.getVerticalScrollBar().setValue(scrollY);
But when the dialog isopened, it doesn't scroll to that position.
I know that something hasn't been updated because a dialog are not visible.
Try adding
this.setVisible(true);
before update the scrollbar, the dialog will be open twice, and in the second time, it display correctly as I want.
But i still don't know how to solve this problem.
Anyone can help me. Thanks.
(sorry for my bad grammar)

First of all:
Get rid of all the repaint() and revalidate() methods. The only time you need to use those methods is when you add/remove components from a visible GUI. In that case the order is revalidate() (to invoke the layout manager) and then repaint() (to paint the components at there new size/location).
Get rid of null layouts. Scrolling works better when you use layout managers and each component determines it own size.
Regarding your problem the maximum value of the scrollbar is only 100 at the time you execute your code, so you can't set the value to 240. I would guess this is because you have not used the pack() method on the dialog before you make it visible. You should be able to set the value of the scrollbar after the pack().
Or, maybe a better approach is the use panel.scrollRectToVisible(....). This seems to work even if you don't pack() the dialog.

Align components on the page top right with GridBagLayout Manager

i am trying to make a login page just like facebook, but the code i have written is not showing it on the top left side instead it is showing at the centre of page, i am using GridBagLayout and anchore for setting text at the FIRST_LINE_END.
final JFrame f2=new JFrame("Admin Main");
f2.setSize(1350,730);
f2.setVisible(true);
f1.setVisible(false);
f2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);![enter image description here][2]
GridBagLayout gbl=new GridBagLayout();
final JPanel p2=new JPanel(gbl){
private Image img = ImageIO.read(new File("F:\\Untitled Folder\\Rohan\\football2.jpg"));
#Override
protected void paintComponent( Graphics g ) {
super.paintComponent(g);
g.drawImage(img, 0,0,1366,730, null);
}
};;
GridBagConstraints g2=new GridBagConstraints();
g2.insets=new Insets(3,3,3,3);
JLabel l2=new JLabel("Admin ID",JLabel.LEFT);
JLabel l3=new JLabel("Password",JLabel.LEFT);
l2.setFont(new Font("TimesRoman",Font.BOLD,16));
l2.setForeground(Color.BLUE);
l2.setBackground(Color.WHITE);
l3.setFont(new Font("TimesRoman",Font.BOLD,16));
l3.setForeground(Color.BLUE);
l3.setBackground(Color.WHITE);
final JTextField t1=new JTextField(15);
final JPasswordField pw1=new JPasswordField(15);
JButton b3=new JButton("Back");
JButton b4=new JButton("Sign in");
f2.add(p2);
g2.anchor=GridBagConstraints.FIRST_LINE_END;
g2.gridx=1;
g2.gridy=1;
p2.add(l2,g2);
g2.gridx=2;
g2.gridy=1;
p2.add(t1,g2);
g2.gridx=1;
g2.gridy=2;
p2.add(l3,g2);
g2.gridx=2;
g2.gridy=2;
p2.add(pw1,g2);
g2.gridx=1;
g2.gridy=3;
p2.add(b3,g2);
g2.gridx=2;
g2.gridy=3;
p2.add(b4,g2);

I see two problems in your current layout:
You put your login panel in the center of the parent BorderLayout (so your panel gets stretched to the size of its container)
You have nothing in your GridBagLayout that will "push" your components to the top and to the left.
There are several options here:
You nest your login panel into several panels (for example using BorderLayout, once with the constraint NORTH and the second time with the constraint WEST).
Add your loginPanel to the WEST and you add a "filler" component to the bottom of the GridBagLayout in order to push the other components to the top.
Here is a demo of the second solution:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.Box;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class TestLoginGridBagLayout {
protected void initUI() throws MalformedURLException {
JFrame frame = new JFrame("Admin Main");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel background = new JLabel(new ImageIcon(new URL(
"http://media1.santabanta.com/full1/Football/Football%20Abstract/football-abstract-6a.jpg"))) {
#Override
public Dimension getPreferredSize() {
Dimension preferredSize = super.getPreferredSize();
Dimension layoutPreferredSize = super.preferredSize();
preferredSize.width = Math.max(preferredSize.width, layoutPreferredSize.width);
preferredSize.height = Math.max(preferredSize.height, layoutPreferredSize.height);
return preferredSize;
}
};
background.setLayout(new BorderLayout());
frame.add(background);
GridBagLayout gbl = new GridBagLayout();
final JPanel loginPanel = new JPanel(gbl);
loginPanel.setOpaque(false);
background.add(loginPanel, BorderLayout.WEST);
JLabel adminIDLabel = new JLabel("Admin ID", JLabel.LEFT);
JLabel passwordLabel = new JLabel("Password", JLabel.LEFT);
adminIDLabel.setFont(new Font("TimesRoman", Font.BOLD, 16));
adminIDLabel.setForeground(Color.BLUE);
adminIDLabel.setBackground(Color.WHITE);
passwordLabel.setFont(new Font("TimesRoman", Font.BOLD, 16));
passwordLabel.setForeground(Color.BLUE);
passwordLabel.setBackground(Color.WHITE);
final JTextField adminID = new JTextField(15);
final JPasswordField password = new JPasswordField(15);
JPanel buttonPanel = new JPanel(new FlowLayout(FlowLayout.TRAILING));
buttonPanel.setOpaque(false);
JButton back = new JButton("Back");
JButton signIn = new JButton("Sign in");
buttonPanel.add(back);
buttonPanel.add(signIn);
GridBagConstraints gbc = new GridBagConstraints();
gbc.insets = new Insets(3, 3, 3, 3);
gbc.anchor = GridBagConstraints.FIRST_LINE_END;
loginPanel.add(adminIDLabel, gbc);
gbc.gridwidth = GridBagConstraints.REMAINDER;
loginPanel.add(adminID, gbc);
gbc.gridwidth = 1;
loginPanel.add(passwordLabel, gbc);
gbc.gridwidth = GridBagConstraints.REMAINDER;
loginPanel.add(password, gbc);
loginPanel.add(buttonPanel, gbc);
GridBagConstraints gbcFiller = new GridBagConstraints();
gbcFiller.weightx = 1.0;
gbcFiller.weighty = 1.0;
gbcFiller.fill = GridBagConstraints.BOTH;
loginPanel.add(Box.createGlue(), gbcFiller);
frame.pack();
frame.setVisible(true);
}
/**
* #param args
*/
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
try {
new TestLoginGridBagLayout().initUI();
} catch (MalformedURLException e) {
e.printStackTrace();
}
}
});
}
}
I also took the liberty of:
Rename your variables to meaningful names (it makes your code easier to read for others)
Replace your custom background image panel with a JLabel
Move your buttons to a nested panel with another LayoutManager
Take another background image since I don't have yours.

If you want it explicitly to be in the top left I'd rather use the NORTHWEST anchor. FIRST_LINE_END for text flowing left to right would also put the text on the right corner and the other way around for right to left.
Also, switch gridx and gridy to start at 0 instead of 1. And increment from as needed from there.
So for example:
g2.anchor=GridBagConstraints.NORTHWEST;
g2.gridx=0;
g2.gridy=0;
p2.add(l2,g2);
g2.gridx=1;
g2.gridy=0;
p2.add(t1,g2);
/*And so on for the rest of the block*/

Use FIRST_LINE_START as anchor value.
g2.anchor=GridBagConstraints.FIRST_LINE_START;