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How to make JScrollPane dynamic adjusting

I am trying to make a dynamic tabs with the option to add new ones in the application and some buttons next to it... To do so I have a main class:
private static void initAndDisplayUI() {
frame = new JFrame(...)
tabbedPane = new TabbedPane();
insertTab(tabbedPane, TabFactory.createTab(), true);
insertNewTabButton(tabbedPane);
...
}
}
Container class:
public class TabbedPane extends JPanel {public TabbedPane() {
this.captions = new TabCaptions();
this.tabs = new ArrayList<Tab>();
this.contentContainer = new JPanel(new BorderLayout());
setLayout(new BorderLayout());
add(captions, BorderLayout.NORTH);
add(contentContainer, BorderLayout.CENTER);
}
...
}
And a TabCaptions:
public class TabCaptions extends JPanel {
private TabCaption selectedTab;
private JComponent tabsPane;
private JScrollPane scrollPane;
private JPanel buttonsPane;
public TabCaptions() {
createUI();
}
private void createUI() {
setLayout(new BoxLayout(this, BoxLayout.X_AXIS));
setBackground(Color.DARK_GRAY);
add(createTabsPane());
add(createButtonsPane());
add(Box.createHorizontalGlue());
}
private JComponent createTabsPane() {
tabsPane = new JPanel();
tabsPane.setOpaque(false);
tabsPane.setLayout(new BoxLayout(tabsPane, BoxLayout.X_AXIS));
scrollPane = new JScrollPane(tabsPane, JScrollPane.VERTICAL_SCROLLBAR_NEVER, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
return tabsPane;
}
...
}
As a result I have a region with the tabs and some button next to it. However the app window draws a scrollPane with some weird size... I would like to display this "add new tab" button right next to the tabs that are created, resize it when the new tab is being added BUT with the functionality to display a scrollbar once it hits the maximum window width. I already have the scrolling but how can I make the behaviour of this dynamic position of new page?

I already have the scrolling
Not based on the code you have provided:
scrollPane = new JScrollPane(tabsPane, JScrollPane.VERTICAL_SCROLLBAR_NEVER, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
return tabsPane;
You need to add the JScrollPane to the frame, so you need to return the scroll pane from the method:
scrollPane = new JScrollPane(tabsPane, JScrollPane.VERTICAL_SCROLLBAR_NEVER, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
//return tabsPane;
return scrollPane;

Java Swing JButton must create 4 new objects and add to JPanel

Okay, so when I press the JButton menuselect1, I want it to create 4 new objecs, attack1 2 3 and 4, and then add them to the JPanel fightmenu.
This is my code so far, it's a mini pokemon game.
First I create all my objects, and then I set the sizes and adds them to the different JPanels
public class MainFrame extends JFrame {
JPanel mainwindow = new JPanel();
JPanel bottom = new JPanel();
JPanel combat = new JPanel();
JPanel selectionmenu = new JPanel();
JPanel fightmenu = new JPanel();
JButton menuselect1 = new JButton("Fight");
JButton menuselect2 = new JButton("Minimons");
JButton menuselect3 = new JButton("Bag");
JButton menuselect4 = new JButton("Run");
JButton attack1 = new JButton("Tackle");
JButton attack2 = new JButton("Lightningbolt");
JButton attack3 = new JButton("Thunder-Shock");
JButton attack4 = new JButton("Hyper-Beam");
JButton poke1 = new JButton("Ekans");
JButton poke2 = new JButton("Pikachu");
public static void main(String[] args){
new MainFrame();
}
public MainFrame(){
super("MiniMon");
setSize(640,640);
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
add(mainwindow);
// SIZES
combat.setPreferredSize(new Dimension(640,452));
bottom.setPreferredSize(new Dimension(640,160));
selectionmenu.setPreferredSize(new Dimension(320,160));
fightmenu.setPreferredSize(new Dimension(320,160));
mainwindow.setLayout(new BorderLayout());
mainwindow.add(combat, BorderLayout.NORTH);
mainwindow.add(bottom, BorderLayout.SOUTH);
combat.setLayout(new BorderLayout());
combat.add(poke1, BorderLayout.NORTH);
combat.add(poke2, BorderLayout.SOUTH);
bottom.setLayout(new BorderLayout());
bottom.add(selectionmenu, BorderLayout.EAST);
bottom.add(fightmenu, BorderLayout.WEST);
selectionmenu.setLayout(new GridLayout(2,2));
selectionmenu.add(menuselect1);
selectionmenu.add(menuselect2);
selectionmenu.add(menuselect3);
selectionmenu.add(menuselect4);
fightmenu.setLayout(new GridLayout(2,2));
setVisible(true);
}
}
I set up my fightmenu to use a 2x2 gridlayout, so I just need to add the 4 objects whenever I press the JButton menuselect1. I'm not really sure how to go about this. I know I should add an eventlistener, but when I tried, it did nothing at all.
I tried doing this:
fightmenu.setLayout(new GridLayout(2,2));
menuselect1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
fightmenupress();
}
private void fightmenupress() {
fightmenu.add(attack1);
fightmenu.add(attack2);
fightmenu.add(attack3);
fightmenu.add(attack4);
}
} );
But it just did nothing.

When you add (or remove) components to a visible GUI, the basic code is:
panel.add(...);
panel.revalidate(); // to invoke the layout manager
panel.repaint(); // to repaint all the components on the panel

I added revalidate and repaint, and it worked!
private void fightmenupress() {
fightmenu.add(attack1);
fightmenu.add(attack2);
fightmenu.add(attack3);
fightmenu.add(attack4);
fightmenu.revalidate();
fightmenu.repaint();
}
} );

How to align JPanel in java

I have a JPanel which is in a box layout but I am unsure how to align the JPanel to center of the window (and stay centered even if window is resized) I've tried looking for a solution but all questions seem over complicated compared to what it is that I'm looking for.
import java.awt.*;
import javax.swing.*;
public class Stacker extends JFrame {
public Stacker() {
super("Stacker");
setSize(430, 200);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// create top panel
JPanel commandPane = new JPanel();
BoxLayout vertical = new BoxLayout(commandPane,
BoxLayout.Y_AXIS);
commandPane.setLayout(vertical);
JButton subscribe = new JButton("Subscribe");
JButton unsubscribe = new JButton("Unsubscribe");
JButton refresh = new JButton("Refresh");
JButton save = new JButton("Save");
commandPane.add(subscribe);
commandPane.add(unsubscribe);
commandPane.add(refresh);
commandPane.add(save);
JMenuItem j1 = new JMenuItem("File");
JMenuItem j2 = new JMenuItem("Open");
JMenuItem j3 = new JMenuItem("Close");
JMenuBar menubar = new JMenuBar();
JMenu menu = new JMenu("Feeds");
menu.add(j1);
menu.add(j2);
menu.add(j3);
menubar.add(menu);
setJMenuBar(menubar);
// create bottom panel
/*JPanel textPane = new JPanel();
JTextArea text = new JTextArea(4, 70);
JScrollPane scrollPane = new JScrollPane(text);
// put them together
FlowLayout flow = new FlowLayout();
setLayout(flow);
add(commandPane);
add(scrollPane); */
setJMenuBar(menubar);
add(commandPane);
setVisible(true);
}
public static void main(String[] arguments) {
Stacker st = new Stacker();
}
}

You say you're using a BoxLayout, but is the JPanel with the BoxLayout the JPanel you want to center, or does it contain the JPanel you want to center?
If it contains the JPanel you want to center, then you can add a glue on either side of the JPanel to be centered. If it is the JPanel you want to center, then you can use GridBagLayout or BoxLayout to achieve the effect you're talking about.
Googling something like "Java center component" will give you a ton of results.

for this idea (still not clear from your description) use GridBagLayout without set for GridBagConstraints
.
.
.
import java.awt.*;
import javax.swing.*;
public class CenteredJPanel {
private JFrame frame = new JFrame("Test");
private JPanel panel = new JPanel();
private JButton subscribe = new JButton("Subscribe");
private JButton unsubscribe = new JButton("Unsubscribe");
private JButton refresh = new JButton("Refresh");
private JButton save = new JButton("Save");
public CenteredJPanel() {
panel.setLayout(new GridBagLayout());
panel.add(subscribe);
panel.add(unsubscribe);
panel.add(refresh);
panel.add(save);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.add(panel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
CenteredJPanel centeredJLabel = new CenteredJPanel();
}
});
}
}

My GUI window doesn't show anything

I'm trying to use a grid layout to make a GUI window. I add all my components and it compiles but when it runs it doesn't show anything. I'm trying to make a simple layout grouped and stacked like this.
{introduction message}
{time label
time input text}
{gravity label
gravity input text}
{answer label
answer text box}
{calculate button clear button}
Here is my code
import javax.swing.*;
import java.awt.*;
public class TurnerRandyFallingGUI extends JFrame
{
final int WINDOW_HEIGHT=500;
final int WINDOW_WIDTH=500;
public TurnerRandyFallingGUI()
{
setTitle("Falling Distance Calculator");
setSize(WINDOW_WIDTH,WINDOW_HEIGHT);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new GridLayout(1, 5));
//labels
JLabel introMessage = new JLabel("Welcome to the Falling distance"+
"calculator");
JLabel timeLabel = new JLabel("Please enter the amount of time "+
"in seconds the object was falling.");
JLabel gravityLabel = new JLabel("Enter the amount of gravity being "+
"forced onto the object");
JLabel answerLabel = new JLabel("Answer");
//text fields
JTextField fTime = new JTextField(10);
JTextField gForce = new JTextField(10);
JTextField answerT = new JTextField(10);
//buttons
JButton calculate = new JButton("Calculate");
JButton clr = new JButton("clear");
//panels
JPanel introP = new JPanel();
JPanel timeP = new JPanel();
JPanel gravityP = new JPanel();
JPanel answerP = new JPanel();
JPanel buttonsP = new JPanel();
//adding to the panels
//intro panel
introP.add(introMessage);
//time panel
timeP.add(timeLabel);
timeP.add(fTime);
//gravity panel
gravityP.add(gravityLabel);
gravityP.add(gForce);
//answer panel
answerP.add(answerLabel);
answerP.add(answerT);
//button panel
buttonsP.add(calculate);
buttonsP.add(clr);
setVisible(true);
}
public static void main(String[] args)
{
new TurnerRandyFallingGUI();
}
}

You've added nothing to the JFrame that your class above extends. You need to add your components to containers whose hierarchy eventually leads to the top level window, to the this if you will. In other words, you have no add(someComponent) or the functionally similar this.add(someComponent)method call in your code above.
Consider adding all of your JPanels to a single JPanel
Consider adding that JPanel to the JFrame instance that is your class by calling add(thatJPanel).
Even better would be to not extend JFrame and just to create one when needed, but that will likely be the subject of another discussion at another time.

Before setVisible (true) statement add following statements:
add (introP);
add (timeP);
add (gravityP);
add (answerP);
add (buttonsP);

There is nothing in your JFrame. That is the reason
import javax.swing.*;
import java.awt.*;
public class TurnerRandyFallingGUI extends JFrame
{
final int WINDOW_HEIGHT=500;
final int WINDOW_WIDTH=500;
public TurnerRandyFallingGUI()
{
//labels
JLabel introMessage = new JLabel("Welcome to the Falling distance"+
"calculator");
JLabel timeLabel = new JLabel("Please enter the amount of time "+
"in seconds the object was falling.");
JLabel gravityLabel = new JLabel("Enter the amount of gravity being "+
"forced onto the object");
JLabel answerLabel = new JLabel("Answer");
//text fields
JTextField fTime = new JTextField(10);
JTextField gForce = new JTextField(10);
JTextField answerT = new JTextField(10);
//buttons
JButton calculate = new JButton("Calculate");
JButton clr = new JButton("clear");
//panels
JPanel introP = new JPanel();
JPanel timeP = new JPanel();
JPanel gravityP = new JPanel();
JPanel answerP = new JPanel();
JPanel buttonsP = new JPanel();
//adding to the panels
//intro panel
introP.add(introMessage);
//time panel
timeP.add(timeLabel);
timeP.add(fTime);
//gravity panel
gravityP.add(gravityLabel);
gravityP.add(gForce);
//answer panel
answerP.add(answerLabel);
answerP.add(answerT);
//button panel
buttonsP.add(calculate);
buttonsP.add(clr);
setLayout(new GridLayout(5, 1));
this.add(introP);
this.add(timeP);
this.add(gravityP);
this.add(answerP);
this.add(buttonsP);
setTitle("Falling Distance Calculator");
this.pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
this.validate();
}
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new TurnerRandyFallingGUI();
}
});
}
}
Consider the following
In GridLayout, the first parameter is Rows, Second is columns
Never set the size of JFrame manually. Use pack() method to decide
the size
Use SwingUtilities.InvokeLater() to run the GUI in another thread.

GUI not showing as intended

I'm trying to draw a gui like shown in the figure, but somehow I'm not able to place the objects in right place (I guess that the problem is with the layout) the textArea is suppose to go in the middle... but is not showing at all
package Chapter22Collections;
import javax.swing.*;
import java.awt.*;
public class Exercise226 extends JFrame {
private JButton jbSort;
private JButton jbReverse;
private JButton jbAdd;
private JButton jbShuffle;
private JLabel jlAddnum;
private JTextArea jTextDisplay;
private JTextField jTextAdd;
public Exercise226() {
jbSort = new JButton("Sort");
jbReverse = new JButton("Reverse");
jbShuffle = new JButton("Shuffle");
jbAdd = new JButton("Add");
jlAddnum = new JLabel("Add number here: ");
jTextDisplay = new JTextArea();
jTextAdd = new JTextField(8);
setLayout(new BorderLayout());
JPanel p1 = new JPanel(new GridLayout(1,3));
p1.add(jlAddnum);
p1.add(jTextAdd);
p1.add(jbAdd);
JPanel p2 = new JPanel(new GridLayout(1,3));
p2.add(jbSort);
p2.add(jbReverse);
p2.add(jbShuffle);
add(p1, BorderLayout.NORTH);
add(jTextDisplay, BorderLayout.CENTER);
add(p2, BorderLayout.SOUTH);
}
public static void main(String... args) {
Exercise226 gui = new Exercise226();
gui.setTitle("Numbers");
gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
gui.setSize(300, 200);
gui.setLocationRelativeTo(null);
gui.setVisible(true);
}
}

The JTextArea is actually where you expect it to be but has no outline border. It is usual to place the component in a JScrollPane which will give this effect:
add(new JScrollPane(jTextDisplay), BorderLayout.CENTER);
or simply
add(new JScrollPane(jTextDisplay));

To make the textArea re-size with the window, try BoxLayout. Box is "A lightweight container that uses a BoxLayout object as its layout manager."
Box p1 = new Box(BoxLayout.X_AXIS);

How could I add spacing/padding between the elements in the frame? So the text area is more visible and centered.
Borders and padding. E.G.
Compared with:
import javax.swing.*;
import java.awt.*;
import javax.swing.border.EmptyBorder;
import javax.swing.border.TitledBorder;
public class Exercise226 {
private JButton jbSort;
private JButton jbReverse;
private JButton jbAdd;
private JButton jbShuffle;
private JLabel jlAddnum;
private JTextArea jTextDisplay;
private JTextField jTextAdd;
private JPanel gui;
public Exercise226() {
gui = new JPanel(new BorderLayout(5,5));
jbSort = new JButton("Sort");
jbReverse = new JButton("Reverse");
jbShuffle = new JButton("Shuffle");
jbAdd = new JButton("Add");
jlAddnum = new JLabel("Add number here: ");
// set the size constraints using columns/rows
jTextDisplay = new JTextArea("Here I am!", 6,20);
jTextAdd = new JTextField(8);
JPanel p1 = new JPanel(new GridLayout(1,3,3,3));
p1.add(jlAddnum);
p1.add(jTextAdd);
p1.add(jbAdd);
JPanel p2 = new JPanel(new GridLayout(1,3,3,3));
p2.add(jbSort);
p2.add(jbReverse);
p2.add(jbShuffle);
JPanel textAreaContainer = new JPanel(new GridLayout());
textAreaContainer.add(new JScrollPane(jTextDisplay));
textAreaContainer.setBorder(new TitledBorder("Text Area Here"));
gui.add(p1, BorderLayout.PAGE_START);
gui.add(textAreaContainer, BorderLayout.CENTER);
gui.add(p2, BorderLayout.PAGE_END);
gui.setBorder(new EmptyBorder(4,4,4,4));
}
public Container getGui() {
return gui;
}
public static void main(String... args) {
JFrame f = new JFrame();
Exercise226 gui = new Exercise226();
f.setContentPane(gui.getGui());
f.setTitle("Numbers");
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.pack();
f.setLocationByPlatform(true);
f.setVisible(true);
}
}
This code:
Primarily provides 'white space' in the GUI using different constructors for the layouts that accept 2 int arguments for horizontal & vertical spacing.
Also adds 2 borders:
An empty border around the entire GUI to provide some spacing between it and the frame decorations.
A titled border around the text area, to make it very obvious.
Does implement a change for one unnecessary part of the original code. Instead of extending frame, it simply retains an instance of one.
Uses the JScrollPane container for the text area, as suggested by #Reimeus. It adds a nice beveled border of its own to an element that needs no scroll bars.
Creates a textAreaContainer specifically so that we can set a titled border to surround the scroll pane - without interfering with its existing border. It is possible to use a CompoundBorder for the scroll pane that consists of the existing border (scroll.getBorder()) & the titled border. However that gets complicated with buttons & other elements that might change borders on selection or action. So to set an 'outermost border' for a screen element (like the text area here) - I generally prefer to wrap the entire component in another container first.
Does not create and show the GUI on the EDT. Swing GUIs should be created and modified on the EDT. Left as an exercise for the user. See Concurrency in Swing for more details.
Old Code
The original code on this answer that provides the 'comparison GUI image' seen above. IT is closely based on the original code but with the text area wrapped in a scroll pane (and gaining a beveled border because of that) & given some text to display.
import javax.swing.*;
import java.awt.*;
public class Exercise226 extends JFrame {
private JButton jbSort;
private JButton jbReverse;
private JButton jbAdd;
private JButton jbShuffle;
private JLabel jlAddnum;
private JTextArea jTextDisplay;
private JTextField jTextAdd;
public Exercise226() {
jbSort = new JButton("Sort");
jbReverse = new JButton("Reverse");
jbShuffle = new JButton("Shuffle");
jbAdd = new JButton("Add");
jlAddnum = new JLabel("Add number here: ");
// set the size constraints using columns/rows
jTextDisplay = new JTextArea("Here I am!", 6,20);
jTextAdd = new JTextField(8);
setLayout(new BorderLayout());
JPanel p1 = new JPanel(new GridLayout(1,3));
p1.add(jlAddnum);
p1.add(jTextAdd);
p1.add(jbAdd);
JPanel p2 = new JPanel(new GridLayout(1,3));
p2.add(jbSort);
p2.add(jbReverse);
p2.add(jbShuffle);
add(p1, BorderLayout.NORTH);
add(new JScrollPane(jTextDisplay), BorderLayout.CENTER);
add(p2, BorderLayout.SOUTH);
}
public static void main(String... args) {
Exercise226 gui = new Exercise226();
gui.setTitle("Numbers");
gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//gui.setSize(300, 200);
gui.pack();
//gui.setLocationRelativeTo(null);
gui.setLocationByPlatform(true);
gui.setVisible(true);
}
}