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How to make method return a panel?

I am making a Java application with tabbed pane, I want some panes to have the same panel layout and structure, I don't want to clutter my code by writing the same code over and over again, so I created a method that returns a JPanel with a structure I want the pane to have.
I am initialising new variables and taking them to the method . My problem is that after I create a panel I can not do anything else in it because it doesn't show up. I can not add labels etc, etc (although if I add the label in the method it does show).
My question is it possible to somehow change the code I've written to make it possible to change it after the panel is returned?
JPanel panel2 = panel2(); // this code bit is in the constructor
JPanel mainPanel = new JPanel(); //Variables needed to create a panel
JPanel LeftPanel = new JPanel();
JPanel RightPanel = new JPanel();
JSplitPane splitPaneH = new JSplitPane();
JPanel panelTop = new JPanel();
JPanel panelBottom = new JPanel();
private JPanel panel2() {
JPanel newPanel = new JPanel();
CreateAPanel(newPanel, LeftPanel,RightPanel,splitPaneH, panelTop,panelBottom);
JLabel label = new JLabel ("lalala");
LeftPanel.add(label,BorderLayout.CENTER);
return newPanel;
}
private JPanel CreateAPanel(JPanel mainPanel, JPanel LeftPanel,JPanel RightPanel, JSplitPane splitPaneH, JPanel panelTop, JPanel panelBottom){
mainPanel.setPreferredSize(new Dimension(1100, 630));
mainPanel.setLayout(new BorderLayout());
LeftPanel = new JPanel();
RightPanel = new JPanel();
splitPaneH = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
panelTop = new JPanel();
panelBottom = new JPanel();
splitPaneH.setTopComponent(panelTop);
splitPaneH.setBottomComponent(panelBottom);
splitPaneH.setDividerLocation(300);
splitPaneH.setPreferredSize(new Dimension(800,630));
mainPanel.add(LeftPanel, BorderLayout.WEST);
mainPanel.add(RightPanel,BorderLayout.EAST);
LeftPanel.setBackground(Color.RED);
LeftPanel.setPreferredSize(new Dimension (300,630));
RightPanel.add(splitPaneH);
return mainPanel;
}

you do not use your return value...
your method CreateAPanel(...) creates the desired panel but you just don't use it
you should adjust your method panel2() in like this:
private JPanel panel2()
{
//JPanel newPanel = new JPanel(); don't create a new panel!
//CreateAPanel(newPanel, LeftPanel,RightPanel,splitPaneH, panelTop,panelBottom);
//instead do this:
JPanel newPanel = CreateAPanel(newPanel, LeftPanel,RightPanel,splitPaneH, panelTop,panelBottom);
JLabel label = new JLabel ("lalala");
LeftPanel.add(label,BorderLayout.CENTER);
return newPanel;
}

It's totally possible to add components to the Panel object afterwards. The only mistake that you have made is that "inside the method body you create new JPanel instances to replace with original param references" so when the method returns there is no effect on the original objects. I suggest doing something different as this:
private JPanel[] CreateAPanel(JPanel mainPanel)
{
mainPanel.setPreferredSize(new Dimension(1100, 630));
mainPanel.setLayout(new BorderLayout());
JPanel leftPanel = new JPanel();
JPanel rightPanel = new JPanel();
JSplitPane splitPaneH = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
JPanel panelTop = new JPanel();
JPanel panelBottom = new JPanel();
splitPaneH.setTopComponent(panelTop);
splitPaneH.setBottomComponent(panelBottom);
splitPaneH.setDividerLocation(300);
splitPaneH.setPreferredSize(new Dimension(800,630));
mainPanel.add(leftPanel, BorderLayout.WEST);
mainPanel.add(rightPanel,BorderLayout.EAST);
leftPanel.setBackground(Color.RED);
leftPanel.setPreferredSize(new Dimension (300,630));
rightPanel.add(splitPaneH);
return new JPanel[]{mainPanel, leftPanel, rightPanel, panelTop, panelBottom};
}

If you want to change or add some more components inside result JPanel you get you can set names to all your components when you create them:
JPanel newPanel = new JPanel();
newPanel .setName("leftPanel");
resultPanel.add(newPanel, BorderLayout.WEST);
Then when you get resultPanel you can get it's components:
Component[] componentList = resultPanel.getContentPane().getComponents();
JPanel leftPanel = null;
for (Component component: componentList) {
if (Objects.equals(component.getName(), "leftPanel")) {
leftPanel = (JPanel) component;
}
}
if (leftPanel != null) {
// do something
}

CardLayout tabs overlapping

I have this very simple code of CardLayout example. The problem is that when I put in different cards elements such as JTextFields or JTextAreas, when running Java example those elements overlay on the first card (see screenshot).
When I click switch button, to switch between tabs, the problem disappears (each element is on the card it is supposed to be), but when I run the code for the first time all or some (or none, sometimes it shows it properly) of the JTextField/Areas overlap on the front view. Can anyone explain it to me what am I doing wrong?
Here is the code:
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class temporary{
CardLayout cards = new CardLayout();
JPanel topPanel = new JPanel();
JPanel bottomPanel = new JPanel();
JButton switchButton = new JButton("Switch!");
temporary(){
JFrame ramka = new JFrame("CardLayout Example");
topPanel.add(switchButton);
ListenForButton lForButton = new ListenForButton();
switchButton.addActionListener(lForButton);
//panel1
JPanel panel1 = new JPanel();
JTextField text1 = new JTextField("TextExample1", 50);
JTextField text2 = new JTextField(50);
panel1.add(text1);
panel1.add(text2);
//panel2
JPanel panel2 = new JPanel();
JTextField text3 = new JTextField("TextExample2",40);
panel2.add(text3);
//panel3
JPanel panel3 = new JPanel();
JTextField text4 = new JTextField("TextExample3", 20);
panel3.add(text4);
panel1.setBackground(Color.white);
panel2.setBackground(Color.lightGray);
panel3.setBackground(Color.gray);
bottomPanel.add(panel1);
bottomPanel.add(panel2);
bottomPanel.add(panel3);
bottomPanel.setLayout(cards);
cards.show(bottomPanel, "CardLayout");
ramka.getContentPane().add(topPanel, BorderLayout.NORTH);
ramka.getContentPane().add(bottomPanel, BorderLayout.CENTER);
ramka.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ramka.setSize(1200, 700);
ramka.setLocationRelativeTo(null);
ramka.setVisible(true);
}
public static void main(String[] args){
new temporary();
}
public class ListenForButton implements ActionListener{
public void actionPerformed(ActionEvent e){
cards.next(bottomPanel);
}
}
}

Java Button Placement using BorderLayout

This code displays nothing, I have exhausted many avenues but it does not display anything on the GUI (I have a main class that calls this as well already). Please help. I am trying to put the two JButtons horizontally at the bottom of the page and the JTextField and JLabel at the center of the screen.
package test;
import javax.swing.*;
import java.awt.*;
public class Gui extends JFrame {
private JLabel label;
private JButton clear;
private JButton copy;
private JTextField textfield;
public Gui(){
super("test");
clear = new JButton("Clear");
copy = new JButton("Copy");
label = new JLabel("");
textfield = new JTextField("enter text here");
JPanel bottom = new JPanel(new BorderLayout());
JPanel subBottom = new JPanel();
subBottom.add(copy);
subBottom.add(clear);
JPanel centre = new JPanel (new BorderLayout());
JPanel subCentre = new JPanel();
subCentre.add(label);
subCentre.add(textfield);
bottom.add(subBottom, BorderLayout.PAGE_END);
centre.add(subCentre, BorderLayout.CENTER);
}
}

Your code is a bit over-complicated. You only need two panels, centre, and buttons. There are two reasons your UI is not showing up:
You never added the panels to the frame
You never set visible to true(Achieve this by using setVisible(true)), unless you did this in the class you ran it in.
One simple way to achieve your desired UI is like so(I added a main method to show the window):
import javax.swing.*;
import java.awt.*;
public class test extends JFrame {
public Test() {
super("test");
JPanel buttons = new JPanel();
JPanel centre = new JPanel();
add(buttons, BorderLayout.SOUTH); //these lines add the
add(centre, BorderLayout.CENTER); //panels to the frame
JButton clear = new JButton("Clear"); // No need
JButton copy = new JButton("Copy"); // to declare
JLabel label = new JLabel("Label"); // these
JTextField textfield = new JTextField("enter text here"); // privately
buttons.add(copy);
buttons.add(clear);
centre.add(label);
centre.add(textfield);
pack();
setLocationRelativeTo(null);
setVisible(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
} //end constructor
//added main method to run the UI
public static void main(String[] args) {
new Experiments();
} //end main
} //end class
And it shows the window:

I got closer but its not pretty code, the JFrame is 500x500 so this works based on that... any better suggestions than what I have?
package lab6;
import javax.swing.*;
import java.awt.*;
public class Gui extends JFrame {
private JLabel label;
private JButton clear;
private JButton copy;
private JTextField textfield;
public Gui(){
super("test");
clear = new JButton("Clear");
copy = new JButton("Copy");
label = new JLabel("label");
textfield = new JTextField("enter text here");
JPanel masterPanel = new JPanel(new BorderLayout());
JPanel top = new JPanel();
top.setPreferredSize(new Dimension(100, 200));
JPanel bottom = new JPanel();
JPanel subBottom = new JPanel();
subBottom.add(copy);
subBottom.add(clear);
JPanel centre = new JPanel ();
JPanel subCentre = new JPanel();
subCentre.add(label);
subCentre.add(textfield);
bottom.add(subBottom);
centre.add(subCentre);
masterPanel.add(bottom, BorderLayout.PAGE_END);
masterPanel.add(top, BorderLayout.PAGE_START);
masterPanel.add(centre, BorderLayout.CENTER);
add(masterPanel);
}
}

How to exactly make JComponents background transparent?

There are two things that I am trying to figure out. First thing, I want to figure out how to make a Jcomponent background transparent. When placing a JPanel into another JPanel that has a color set as the background, the JPanel that is set within the other JPanel has a white background that I can't seem to get rid of. I tried using the firstpanel.setOpache function and repaint but it doesn't do anything.
And second, I noticed that putting a JPanel within another JPanel thats within another JPanel compresses it size. The images below will show what I am trying to describe. I want to know what to do to avoid compressing the JPanel size and still able to put it within two levels of other JPanels . The code below is what I am practicing with.
import javax.swing.*;
import java.awt.*;
public class LearningFrame extends JFrame {
private JLabel userLabel;
private LearningFrame(){
JPanel backGroundPanel = new JPanel();
JPanel mainPanel = new JPanel();
JPanel firstPanel = new JPanel();
JPanel secondPanel = new JPanel();
userLabel = new JLabel("User");
userLabel.setFont(new Font("Arial",1 ,24));
backGroundPanel.setBackground(new Color(247,211,53));
// backGroundPanel.setLayout(new BoxLayout(backGroundPanel,BoxLayout.Y_AXIS));
setContentPane(backGroundPanel);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(1200,800);
setLocationRelativeTo(null);
//backGroundPanel.setLayout(null);
mainPanel.setLayout(new GridLayout(1,2));
firstPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
secondPanel.setLayout(new BoxLayout(secondPanel,BoxLayout.Y_AXIS));
// firstPanel.setBackground(new Color(211,43,185));
secondPanel.setBackground(new Color(34,233,44));
JButton button = new JButton("Click");
JButton button2 = new JButton("Click");
JButton button3 = new JButton("Click");
JButton button4 = new JButton("Click");
firstPanel.add(button);
firstPanel.add(button2);
firstPanel.add(userLabel);
secondPanel.add(button3);
secondPanel.add(button4);
mainPanel.add(firstPanel);
mainPanel.add(secondPanel);
backGroundPanel.add(mainPanel);
setVisible(true);
}
public JPanel logPanel() {
JPanel logInPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
JTextField userTextField = new JTextField(14);
JTextField passTextField = new JTextField(14);
userLabel = new JLabel("Username: ");
JLabel passLabel = new JLabel("Password: ");
passLabel.setFont(new Font("Arial", Font.BOLD, 24));
userLabel.setFont(new Font("Arial", Font.BOLD, 24));
logInPanel.add(userLabel);
logInPanel.add(userTextField);
logInPanel.add(passLabel);
logInPanel.add(passTextField);
logInPanel.setOpaque(true);
logInPanel.repaint();
return logInPanel;
}
public static void main(String[] args){
LearningFrame x = new LearningFrame();
}
}

Just use
firstPanel.setOpaque(false);
This is will make the background of the component invisible, but you will still be able to see any components that are positioned inside it.

How do I create the following GUI in Java Swing?

I want to create the following GUI with Java Swing.
Since I'm not experienced enough with Java Swing, I'm not sure how to exactly recreate that GUI.
I've tried using GridLayout which looks like this:
I've tried other LayoutManagers but due to my inexperience, I couldn't get anything even remotely resembling the GUI I want to achieve.
I probably have to use GridBagLayout but I've tried it and simply wasn't able to get anything done.
I'm not sure how to exactly use GridBagLayout, especially since there is a variance of the amount of colums needed (2, 2 and then 3).
Here is the code used for creating the second GUI:
import java.awt.*;
import javax.swing.*;
public class GUITest extends JFrame {
public GUITest() {
super("Testing Title");
Container pane = getContentPane();
pane.setLayout(new GridLayout(3,1));
pane.add(getHeader());
pane.add(getTextArea());
pane.add(getButtonPanel());
}
public JComponent getHeader() {
JPanel labelPanel = new JPanel();
labelPanel.setLayout(new GridLayout(1,2));
labelPanel.setSize(getPreferredSize());
JLabel labelLocal = new JLabel("Left value: ", JLabel.CENTER);
JLabel labelDB = new JLabel("Right value: ", JLabel.CENTER);
labelPanel.add(labelLocal);
labelPanel.add(labelDB);
return labelPanel;
}
public JComponent getTextArea() {
JPanel textPanel = new JPanel();
textPanel.setLayout(new GridLayout(1,2,5,0));
JTextArea testTextArea = new JTextArea();
testTextArea.setEditable(false);
JScrollPane sp1 = new JScrollPane(testTextArea);
JTextArea testTextArea2 = new JTextArea();
JScrollPane sp2 = new JScrollPane(testTextArea2);
testTextArea2.setEditable(false);
testTextArea.setText("Hello Hello Hello\nTesting!\ntesterino\ntesteroni");
testTextArea2.setText("Hello Hello Hello\nTesting!\ntest\nABC123\ncdef123\nhijk123");
textPanel.add(sp1);
textPanel.add(sp2);
return textPanel;
}
public JComponent getButtonPanel() {
JPanel inner = new JPanel();
inner.setLayout(new FlowLayout((FlowLayout.CENTER),0,100));
inner.add(new JButton("Do something"));
inner.add(new JButton("Do something different"));
inner.add(new JButton("Do something even more different"));
return inner;
}
public static void main(String[] args) {
GUITest e = new GUITest();
e.setSize(700, 500);
e.setVisible(true);
e.setResizable(false);
e.setDefaultCloseOperation(EXIT_ON_CLOSE);
e.setLocationRelativeTo(null);
}
}
I'm thankful for any kind of support!

You could try something like this:
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.awt.*;
public class Example {
public static void main(String[] args) {
JFrame jFrame = new JFrame();
jFrame.setTitle("Testing Title");
jFrame.setLocationRelativeTo(null);
JPanel mainPanel = new JPanel(new BorderLayout());
mainPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
JPanel listPanel = new JPanel(new GridLayout(0, 2, 10, 0));
JPanel leftListPanel = new JPanel(new BorderLayout(0, 10));
JLabel leftLabel = new JLabel("Left value:");
JTextArea leftTextArea = new JTextArea("Hello Hello Hello\nTesting!\ntest");
JScrollPane leftScrollPane = new JScrollPane(leftTextArea);
leftListPanel.add(leftLabel, BorderLayout.NORTH);
leftListPanel.add(leftScrollPane, BorderLayout.CENTER);
JPanel rightListPanel = new JPanel(new BorderLayout(0, 10));
JLabel rightLabel = new JLabel("Right value:");
JTextArea rightTextArea = new JTextArea("Hello Hello Hello\nTesting!\ntest");
JScrollPane rightScrollPane = new JScrollPane(rightTextArea);
rightListPanel.add(rightLabel, BorderLayout.NORTH);
rightListPanel.add(rightScrollPane, BorderLayout.CENTER);
listPanel.add(leftListPanel);
listPanel.add(rightListPanel);
mainPanel.add(listPanel, BorderLayout.CENTER);
JPanel buttonsPanel = new JPanel(new BorderLayout());
buttonsPanel.setBorder(new EmptyBorder(10, 10, 10, 10));
buttonsPanel.add(new JButton("Do something"), BorderLayout.WEST);
buttonsPanel.add(new JButton("Do something different"), BorderLayout.CENTER);
buttonsPanel.add(new JButton("Do something even more different"), BorderLayout.EAST);
mainPanel.add(buttonsPanel, BorderLayout.SOUTH);
jFrame.setContentPane(mainPanel);
jFrame.pack();
jFrame.setVisible(true);
}
}
Explanation:
Firstly I created a main JPanel with a BorderLayout. This JPanel will be split horizontally, the CENTRE component will be another JPanel containing the text areas and labels, and the SOUTH component will be a JPanel containing the buttons.
The JPanel that contains the text areas is given a GridLayout so that it can be easily split vertically, and is also given a hgap of 10 to add some spacing.
The left and right JPanels that are put into that are both the same. They have a BorderLayout with a vgap to add spacing. The NORTH component is a JLabel and the CENTRE component is a JScrollPane containing a JTextArea.
Finally, the SOUTH component of the main JPanel is another JPanel which is given a BorderLayout again. Three JButtons are added with WEST, CENTRE and EAST attributes allocated accordingly.
The overall result looks like:

Here is your code with just some little changes :)
import java.awt.*;
import javax.swing.*;
public class GUITest extends JFrame {
public GUITest() {
super("Testing Title");
Container pane = getContentPane();
pane.setLayout(new BorderLayout());//Modified Layout to BorderLayout
pane.add(getHeader(),BorderLayout.NORTH); //BorderLayout.NORTH
pane.add(getTextArea(),BorderLayout.CENTER);//BorderLayout.CENTER
pane.add(getButtonPanel(),BorderLayout.SOUTH);//BorderLayout.SOUTH
}
public JComponent getHeader() {
JPanel labelPanel = new JPanel();
labelPanel.setLayout(new GridLayout(1,2));
labelPanel.setSize(getPreferredSize());
JLabel labelLocal = new JLabel("Left value: ", JLabel.CENTER);
JLabel labelDB = new JLabel("Right value: ", JLabel.CENTER);
labelPanel.add(labelLocal);
labelPanel.add(labelDB);
return labelPanel;
}
public JComponent getTextArea() {
JPanel textPanel = new JPanel();
textPanel.setLayout(new GridLayout(1,2,5,0));
JTextArea testTextArea = new JTextArea();
testTextArea.setEditable(false);
JScrollPane sp1 = new JScrollPane(testTextArea);
JTextArea testTextArea2 = new JTextArea();
JScrollPane sp2 = new JScrollPane(testTextArea2);
testTextArea2.setEditable(false);
testTextArea.setText("Hello Hello Hello\nTesting!\ntesterino\ntesteroni");
testTextArea2.setText("Hello Hello Hello\nTesting!\ntest\nABC123\ncdef123\nhijk123");
textPanel.add(sp1);
textPanel.add(sp2);
return textPanel;
}
public JComponent getButtonPanel() {
JPanel inner = new JPanel();
inner.setLayout(new FlowLayout());//Modified to standard FlowLayout
inner.add(new JButton("Do something"));
inner.add(new JButton("Do something different"));
inner.add(new JButton("Do something even more different"));
return inner;
}
public static void main(String[] args) {
GUITest e = new GUITest();
e.pack(); //Modified setSize(700,500) to pack()
e.setVisible(true);
e.setResizable(false);
e.setDefaultCloseOperation(EXIT_ON_CLOSE);
e.setLocationRelativeTo(null);
}
}

GridLayout sizes all cells the same, i.e. your outer layout with 3 rows and 1 column makes 3 cells of all the same size.
Instead, use BorderLayout for your outer container and add the top, mid and lower panels with constraints BorderLayout.NORTH, BorderLayout.CENTER and BorderLayout.SOUTH respectively