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Jbuttons inside JPanel with background image in right | bottom corner

Can somebody explain me how can I put few jButtons inside jLabel which have background image like on this image? The main jFrame is undecorated and is set to full screen.
I saw a lot of different examples like
this or like this, but these examples are showing only single button in jPanel.

Personally, I'd avoid using a JLabel for this purpose, it does not calculate it's required size based on it's content, but rather off it's icon and text properties.
This might be a good or bad thing, but it can catch your unawares if you're not aware of it.
Instead, I'd use a customised JPanel, which would allow you to define things like the resize and fill rules, for example and for example
Now, once you have that covered, you need to create a panel of your buttons. I prefer to create a dedicated class, as it makes it easier to isolate functionality and management, but that's me...
public class ButtonPane extends JPanel {
public ButtonPane() {
setLayout(new GridBagLayout());
setBorder(new EmptyBorder(8, 8, 8, 8));
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
gbc.insets = new Insets(2, 2, 2, 2);
add(new JButton("Button 1"), gbc);
add(new JButton("Button 2"), gbc);
add(new JButton("Button 3"), gbc);
}
}
Next, you need to add this panel to your background
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(backgroundPane);
frame.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.weightx = 1;
gbc.weighty = 1;
gbc.anchor = GridBagConstraints.SOUTHEAST;
gbc.insets = new Insets(30, 30, 30, 30);
ButtonPane buttonPane = new ButtonPane();
frame.add(buttonPane, gbc);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
Which can generate something like...
Have a look at Laying Out Components Within a Container and How to Use GridBagLayout for some more details

These examples are truly good enough, I think you should just learn more about swing.
For now, You could simply do:
JFrame frame = new JFrame("Hi there");
JButton b1 = new JButton("1");
JButton b2 = new JButton("2");
frame.add(b1);
frame.add(b2);
b1.setBounds(60, 60, 40, 40);
b2.setBounds(10, 10, 40, 40);
frame.setVisible(true); //in case, add frame.setLayout(null);
You can of course add buttons to JPanel instead of JFrame

How to set JButton size with GridBagLayout

I want to set the size of my JButtons that are at the center of my screen to become larger but I can't seem to find how to do that using GridBagLayouts.
Here is how it looks like :
Here is my code :
// Client
c.fill = GridBagConstraints.BOTH;
c.anchor = GridBagConstraints.CENTER;
c.gridy = 5;
c.gridx = 5;
c.gridwidth = 1;
c.gridheight = 1;
c.insets = new Insets(10, 1, 1, 10);
p.add(b[0], c);
// Server
c.fill = GridBagConstraints.BOTH;
c.anchor = GridBagConstraints.CENTER;
c.gridy = 10;
c.gridx = 5;
c.gridwidth = 1;
c.gridheight = 1;
c.insets = new Insets(10, 1, 1, 10);
p.add(b[1], c);
I want the buttons to take up a larger portion of the empty space around them.

More information was added: Buttons have 50% of the width and [about] 20% of the height of parent [together 50% height including the space in between]. (Slightly rewritten to match the suggestion.)
Solution
Combination of simple Layouts Layouts. Although if you do it like this you will have 3 columns or 3 rows which can't be joined, the rest can easily be changed later:
// row variation
JPanel parent = new JPanel();
parent.setLayout(new GridLayout(3, 1));
parent.add(new JPanel()); // placeholder for 1st row
JPanel row = new JPanel(); // 2nd row
row.setLayout(new GridLayout(1, 3)); // create 3 cells of equal size
row.add(new JPanel()); // 2nd row, 1st cell placeholder
// now you have a 33% x 33% (oops) rectangle in the middle
JPanel controls = new JPanel();
controls.setLayout(new GridLayout(2, 1, 10, 10));
controls.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10);
controls.add(new JButton("Client"));
controls.add(new JButton("Server"));
row.add(controls); // add 2nd row, 2nd cell
row.add(new JPanel()); // 2nd row, 3rd cell placeholder
parent.add(row); // add 2nd row
parent.add(new JPanel()); // placeholder for 3rd row
Easy, but you won't be able to join the cells later:
JPanel parent = new JPanel();
parent.setLayout(newGridLayout(9, 9));
Bottom line: combine different layout managers, put your 2 buttons inside a panel and put some placeholders inside, then it should also work fine with GridBagLayout. That said, I would try to stay flexible by writing reusable components which can easily be combined with any layout manager. Then you don't have to use placeholders superfluous code in order to display the components correctly.
Old Answer
Alternative Solution: Use BoxLayout
BoxLayout is more intuitive and easier to understand when looking at code (of course this is only an opinion).
Decide how your window is structered (is it more like big horizontal components on top of each other PAGE_AXIS or big vertical components next to each other LINE_AXIS) and use this as the outer BoxLayout:
JPanel content = new JPanel(); // or frame
content.setLayout(new BoxLayout(content, BoxLayout.LINE_AXIS));
Add the components along the axis, where you have more than one component along the other axis use a 2nd BoxLayout. You can space components by creating rigid areas (empty rectangles always having the same size) or by adding glue (expanding like gum together with the components).
content.add(BoxLayout.createHorizntalGlue());
JPanel col = new JPanel();
col.setLayout(new BoxLayout(col, BoxLayout.PAGE_AXIS));
JButton clientBtn = new JButton("Client");
JButton serverBtn = new JButton("Server");
col.add(BoxLayout.createVerticalGlue());
col.add(clientBtn);
col.add(BoxLayout.createRigidArea(new Dimension(1, 10)));
col.add(serverBtn);
col.add(BoxLayout.createVerticalGlue());
content.add(col);
content.add(BoxLayout.createHorizontalGlue());

I can't imagine what do you want, but if you want your button to fill around, you can add
c.weightx = ...; //Specifies how to distribute extra horizontal space.
or c.weighty = ...; //Specifies how to distribute extra vertical space.

button.setMargin( new Insets(50, 50, 50, 50) );
This will add extra space to the button and allow the layout managers to do their job based on the preferred size of the button.

making a full size panel, with grid bag layout

I am making a program with 3 JSliders, for r,g,b and i want to add a panel that will change it's color for the chosen color in the sliders, everything works for me except one thing, I don't know how to make the panel in the full size of the screen, this is the best I could do, but this is still kind of small and I want to make the panel full size. can any one show me how to do it?
The program is kind of long so I will only send the part of the gridbaglayout and the panel.
private JPanel panel;
public delta(){
setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
panel = new JPanel();
panel.setBackground(new Color(0 ,0 ,0));
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 2;
c.gridy = 6;
c.gridwidth = 3;
c.gridheight = 3;
add(panel ,c);

Simply add your panel to Jframe
jframe.add(yourpanel)
This code without any Layout will fill the window.
Edit:
JFrame frame = new JFrame();
frame.setSize(500,500);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel label = new JLabel("HELLO");
frame.add(label);
This fills the JFrame with JLabel.

JInternal Frame Over JPanel

I need some help in JInternalFrame within JPanel's Area.I have a JFrame which contains
JPanel added to its ContentPane.JFrame Contains Menu when i click one of its Menu item i
need JInternal Frame to be added on top of the contentpane.The Code i have given so far,
JDesktopPane desktop = new JDesktopPane();
desktop.setLayout(new BorderLayout());
JPanel topPanel = new JPanel();
GridBagLayout gbl_contentPane = new GridBagLayout();
gbl_contentPane.columnWidths = new int[] { 0, 0, 0, 0 };
gbl_contentPane.rowHeights = new int[] { 0, 0, 0, 0 };
gbl_contentPane.columnWeights = new double[] { 1.0, 6.0, 1.0,
Double.MIN_VALUE };
gbl_contentPane.rowWeights = new double[] { 0.0, 8.0, 0.0,
Double.MIN_VALUE };
topPanel.setLayout(gbl_contentPane);
JPanel left = new JPanel();
GridBagConstraints gbc_left = new GridBagConstraints();
gbc_left.insets = new Insets(0, 0, 5, 5);
gbc_left.fill = GridBagConstraints.BOTH;
gbc_left.gridx = 0;
gbc_left.gridy = 1;
topPanel.add(left, gbc_left);
JPanel middle = new JPanel();
GridBagLayout gbl_middle = new GridBagLayout();
gbl_middle.columnWeights = new double[] { 1.0 };
middle.setLayout(gbl_middle);
GridBagConstraints gbc_middle = new GridBagConstraints();
gbc_middle.insets = new Insets(0, 0, 5, 5);
gbc_middle.fill = GridBagConstraints.BOTH;
gbc_middle.gridx = 1;
gbc_middle.gridy = 1;
topPanel.add(middle, gbc_middle);
GridBagConstraints gbc = new GridBagConstraints();
JPanel panel1 = new JPanel();
Border eBorder = BorderFactory.createEtchedBorder();
panel1.setBorder(BorderFactory.createTitledBorder(eBorder, "70pct"));
gbc.gridx = 0;
gbc.gridy = 0;
gbc.fill = GridBagConstraints.BOTH;
gbc.weightx = gbc.weighty = 30;
middle.add(panel1, gbc);
panel1.setLayout(new MigLayout("", "[944.00,grow][353.00]",
"[6.00][128.00,grow][]"));
/*lblHeader = new JLabel(
"<html>Indira Institute of Technology<br>Tatabad<br>Karpagam Complex Stop<br>Coimbatre</html>");
lblHeader.setIcon(new ImageIcon(
"C:\\Users\\Prakash\\Desktop\\images.jpg"));
panel1.add(lblHeader, "cell 0 1 2 1,alignx center,aligny center");*/
JPanel panel2 = new JPanel();
gbc = new GridBagConstraints();
panel2.setBorder(BorderFactory.createTitledBorder(eBorder, "30pct"));
gbc.gridy = 1;
gbc.gridwidth = gbc.gridheight = 1;
gbc.fill = GridBagConstraints.BOTH;
gbc.anchor = GridBagConstraints.NORTHWEST;
gbc.weightx = gbc.weighty = 70;
gbc.insets = new Insets(2, 2, 2, 2);
middle.add(panel2, gbc);
panel2.setLayout(new MigLayout(
"",
"[30px][69.00px][144.00][68.00][][159.00px][59.00px][65px][28.00][]",
"[20px:n,grow 50,shrink 50][20px:n,grow 50,shrink 50][20px:n,grow 50,shrink 50][20px:n,grow 50,shrink 50][30.00][48.00:n,grow 50,shrink 50]"));
getContentPane.add(topPanel);
I have never used the DesktopPane in this(I don't know how to make use of this in this situation) And The Screen So far is as follows,
Now I need the JInternalFrame to be added for the Previous Screen as Follows,
I am aware that i can only be able to add a JInternalFrame to the DesktopPane.But i
Already Filled my ContentPane with JPanel to show its content.How can i achieve Jinternal
Frame to be added in this JFrame.Kindly give your valuable suggestions.

Not really the right direction. You original panel is under the control of layout manager, this means that when you add the JInternalFrame to it, the layout manager wants to try and layout it out.
Generally speaking, a JInternalFrame wants to reside in a container which is unmanaged, allowing it to be positioned and sized independently of the content.
A possible solution might be to take advantage of the glass pane for the JInternalFrame instead, for more details see How to Use Root Panes
Another solution might be to use a JLayeredPane. Basically, you would start by setting the layout manager of the JLayeredPane to something link BorderLayout add the first panel to it and then add a second, transparent pane, with no layout, above it. You would add the JInternalFrames to this second panel.
See How to Use Layered Panes for more details
The question that jumps out at me though is...why? Why wouldn't you just use some kind of dialog instead? See How to Make Dialogs for more details

What is it what you really want?
You wrote you already have your content pane added to your frame. JDesktopPane has to have its own space reserved. If you don't have or you don't want to reserve space for the internal frames in your main frame, then maybe you don't even want it to be part of the main frame. In this case you might want to use child JDialogs instead of JInternalFrames.
So either add your JDesktopPane to your main frame (having its space reserved) or use child JDialogs which can be modal or not and can overlap any part of the main frame. JInternalFrames are only visible in the area of the JDesktopPane while child JDialogs can "float" over your main frame.
Check out this Oracle documentation: How to Use Internal Frames
And How to Make Dialogs.

Set minimum height for each component in JScrollPane

Is there any method I could implement that will ensure each button within the pane maintains a minimum height? I have attempted using itembutton.setSize() method but it has no effect.
JPanel itemPanel = new JPanel();
itemPanel.setLayout(new GridLayout(0,1));
for(final Item i: list){
JButton itemButton = new JButton(i.getName());
itemPanel.add(itemButton);
}
JScrollPane itemPane = new JScrollPane(itemPanel);

itembutton.setMinimumSize(minimumSize) ?
Edit: Just found that, as this java tutorial seems to tell, there is no way to do that with GridLayout.
Each component takes all the available space within its cell, and each cell is exactly the same size
So I guess you'll have to try another layout. I can suggest (don't know if it's well suited but it works) GridBagLayout. Example with 2 buttons:
itemPanel.setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 0;
c.weightx = 0.5;
itemPanel.add(new JButton("A"), c);
c.gridx = 1;
c.weightx = 0.5;
itemPanel.add(new JButton("B"), c);
Have a look to http://docs.oracle.com/javase/tutorial/uiswing/layout/index.html