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Panel not showing object [duplicate]

I have a JPanel and JButton on the JFrame.
on runtime add JLabel to JPanel When click JButton.
I use of the following code:
panel.setLayout(null);
jLabel _lbl=new jLabel();
_lbl.setText("Label");
panel.add(_lbl);
panel.validate();
but no display any JLabel in JPanel.

I see you create a JLabel called _lbl:
JLabel _lbl=new JLabel();
but you never add it to your panel. Instead you add a new JLabel with no text to your panel:
panel.add(new JLabel());
This would ofcourse construct an empty label which wont be visible.
Also try calling revalidate() and repaint() on your JPanel instance after adding the JLabel like so:
JLabel _lbl=new JLabel("Label");//make label and assign text in 1 line
panel.add(_lbl);//add label we made
panel.revalidate();
panel.repaint();
With this you may also need to call pack() on your frames instance so as to resize the JFrame to fit the new components.
Also please never use a null/Absolute layout this is very bad practice (unless doing animation) and may prove to be problematic and very hard to use.
Rather use a LayoutManager:
A Visual Guide to Layout Managers
or if you only have a single component on the JPanel simply call add(label); as it will stretch to the JPanel size.
UPDATE:
Here is a small sample. Simply adds JLabels to the JPanel each time JButton is pressed:
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class JavaApplication116 {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new JavaApplication116().createAndShowUI();
}
});
}
private void createAndShowUI() {
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
initComponents(frame);
frame.setResizable(false);
frame.pack();
frame.setVisible(true);
}
private void initComponents(final JFrame frame) {
final JPanel panel = new JPanel(new FlowLayout());
JButton button = new JButton("Add label");
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
JLabel _lbl = new JLabel("Label");//make label and assign text in 1 line
panel.add(_lbl);//add label we made
panel.revalidate();
panel.repaint();
frame.pack();//so our frame resizes to compensate for new components
}
});
frame.getContentPane().add(panel, BorderLayout.CENTER);
frame.getContentPane().add(button, BorderLayout.SOUTH);
}
}

How do I add other swing components in a specific swing tabbed pane?

I have just started learning Java Swing and I am making a application form sort of project and I want to add more components like buttons,text areas and other in specific tab but I am not able to.
The code is given below:
import javax.swing.*;
public class TabbedPaneExample {
JFrame f;
TabbedPaneExample(){
f=new JFrame("Hotel Appication Form");
JTextArea ta=new JTextArea(400,400);
JPanel p1=new JPanel();
p1.add(ta);
JPanel p2=new JPanel();
JPanel p3=new JPanel();
JTabbedPane tp=new JTabbedPane();
tp.setBounds(39,20,500,500);
tp.add("form",p1);
tp.add("preferences",p2);
tp.add("FaQ's",p3);
f.add(tp);
f.setSize(600,600);
f.setVisible(true);
//JButton
JButton b = new JButton("Submit");
b.setBounds(50,50,30,20);
f.add(b);
//JLabel
}
public static void main(String[] args) {
new TabbedPaneExample();
}
}
The screenshot of the output is attached here

In this code example simple frame with tabbed panel and simple components in each tab.
Your problem was incorrect adding components to JPanel.
Hope that helps you!
output1 output2
import java.awt.GridLayout;
import javax.swing.*;
public class test {
private static void createAndShowGUI() {
// Create and set up the window.
final JFrame frame = new JFrame("Split Pane Example");
// Display the window.
frame.setSize(500, 300);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// set grid layout for the frame
frame.getContentPane().setLayout(new GridLayout(1, 1));
JTabbedPane tabbedPane = new JTabbedPane(JTabbedPane.TOP);
JPanel panel = new JPanel();
JPanel panel2 = new JPanel();
JButton button = new JButton("Button");
JLabel label = new JLabel("Label");
JTextField textField = new JTextField("TextField");
panel.add(button);
panel.add(label);
panel2.add(textField);
tabbedPane.addTab("Tab1", panel);
tabbedPane.addTab("Tab2", panel2);
frame.getContentPane().add(tabbedPane);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}

Java Swing 13 GridLayout does not exist?

I can't seem to get a swing GridLayout to work in java 13. The error is that GridLayout cannot be resolved to a type in the following code:
import javax.swing.*;
public class GameFrame extends JFrame {
public static final void NewFrame() {
new GameFrame();
}
public GameFrame() {
this.setSize(1600, 800);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setTitle("The Game");
this.setVisible(true);
this.setResizable(false);
JPanel MainPanel = new JPanel();
MainPanel.setLayout(new GridLayout());
}
}

The issue is caused by the class not being imported.
import java.awt.GridLayout;
Since it is not in the swing package it doesn't get imported with the star import.
Also it is better to use explicit imports.

This might be related to the fact that panel is empty. Try running this code and it should work.
public class GridLayoutTest {
private static JButton[] arrayBtn;
public static void main(String[] args) {
// the frame that contains the components
JFrame frame = new JFrame("GridLayoutTest from JCG");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// set the size of the frame
frame.setSize(350, 350);
// set the rows and cols of the grid, as well the distances between them
GridLayout grid = new GridLayout(5, 3, 10, 10);
// what layout we want to use for our frame
frame.setLayout(grid);
// add a text field with a specified text to the frame
JTextArea text = new JTextArea();
text.setText("Result");
text.setEditable(false);
frame.add(text);
// add buttons to the frame
frame.add(new JButton("+"));
frame.add(new JButton("="));
arrayBtn = new JButton[10];
// add JButtons dynamically
for(int i=0; i < arrayBtn.length; i++) {
arrayBtn[i] = new JButton(Integer.toString(i));
frame.add(arrayBtn[i]);
}
frame.setVisible(true);
}
}

Having trouble with creating a JFrame and adding text to it

I've been trying to setup a JFrame with text but I'm having trouble. I can create the JFrame, but I can't get a background color or text to work with it.
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
class FundManager {
JFrame window;
JPanel panel;
JLabel text;
public void createWindow()
{
//Create the window
window = new JFrame();
window.setVisible(true);
window.setSize(960, 540);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setLocationRelativeTo(null);
//Create the panel
panel = new JPanel();
panel.setBackground(Color.RED);
//Create the label
text = new JLabel("test");
}
public static void main(String args[]) {
FundManager.createWindow();
}
}
My createWindow() method is not running and I get the error:
cannot make a static reference to to the non-static method.
However, when I make it static the whole program breaks.

The issue here is that you need an instance of FundManager before you can call the method createWindow(). Try the code below instead.
new FundManager().createWindow();

First of all, you cannot make a call to FundManager.createWindow(), because createWindow() is not a static method. You need an instance of FundManager.
Furthermore, you are not adding the panel nor the text field to the frame. You are only declaring them. This is a quick example of how you could locate the elements inside the frame:
JFrame window;
JPanel panel;
JLabel text;
public void createWindow() {
// Create the window
window = new JFrame();
window.setVisible(true);
window.setSize(960, 540);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setLocationRelativeTo(null);
// Create the panel
panel = new JPanel();
panel.setPreferredSize(new Dimension(500, 500));
panel.setBackground(Color.RED);
// Create the label
text = new JLabel("test");
text.setPreferredSize(new Dimension(200, 30));
text.setLocation(100, 100);
panel.add(text);
window.getContentPane().add(panel);
window.pack();
}
And run this with:
new FundManager().createWindow();

problem in nested Jpanel over Jframe

I have a JFrame and a Jpanel over that in which various buttons are placed.so on click of a button I have called a new class which is also having containers placed in a Jpanel.so I want to show that new class panel over the main Jframe panel.How can I do that?
And if we use card layout in it then how can i use that as on click button i have called an object of a new class.
as
Card layout consider each component in a container as card and i want whole Jpanel as a card so is it possible to do that???
Can We do nesting of Jpanels in it?
Please suggest me a right way to do that?
here is SSCCE:
// this is the main class on which i want to use panel of other class
public class mymain
{
JFrame jframe = new JFrame();
JPanel panel = new JPanel();
BorderLayout borderlayout = new BorderLayout();
public mymain()
{
jframe.setLayout(borderlayout);
JMenuBar menubar = new JMenuBar();
jframe.setJMenuBar(menubar);
JButton home_button = new JButton("HOME");
menubar.add(home_button);
jframe.getContentPane().add(panel,BorderLayout.CENTER);
panel.setLayout(new GridBagLayout());
//here used containers over that frame
and call it from main()
}
here is another class to manage category is
public class manageCategory
{
JPanel panel = new JPanel();
GridBagLayout gridbglayout = new GridBagLayout();
GridBagConstraints gridbgconstraint = new GridBagConstraints();
public manageCategory()
{
panel.setLayout(new BorderLayout());
// i have again here used containers placed with grid bag layout
}
}
So now i want that as i click on home button used in mymain class then the panel that is used in manageCategory() should be displayed on the same panel.and when i again click on home button then the mymain panel get displayed.how can i do that???

I would advise you to use a CardLayout for this task.
Updated example with JPanel and "classes":
static class MainPanel extends JPanel {
public MainPanel(final Container frame) {
add(new JButton(new AbstractAction("Click to view next") {
#Override
public void actionPerformed(ActionEvent e) {
frame.add(new NextPanel(), "NextPanel");
((CardLayout) frame.getLayout()).show(frame, "NextPanel");
}
}));
}
}
static class NextPanel extends JPanel {
public NextPanel() {
add(new JLabel("Next page in the card layout"));
}
}
public static void main(String[] args) throws Exception {
JFrame frame = new JFrame("Test");
frame.setLayout(new CardLayout());
frame.add(new MainPanel(frame.getContentPane()), "MainPanel");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 300);
frame.setVisible(true);
}

CardLayout is one of possible ways, but there are another options valid or required by most completed GUI
1) BorderLayout, because there only one JComponent can occupate decision area
someContainer.add(myPanel, BorderLayout.CENTER)
revalidate();
repaint();
2) GridBagLayout
before anything you have to get declared GridBagConstraints from myOldComponent layed by GridBagLayout
myContainer.setVisible(myOldComponent);
//or
myContainer.remove(myOldComponent);
myContainer.add(myNewComponent, gbc);
revalidate();
repaint();

You can
JFrame myFrame = new JFrame();
JPanel panel1 = new JPanel();
Panel1.setVisible(true);
myFrame.add(panel1);
JPanel panel2 = new JPanel();
Panel2.setVisible(false);
myFrame.add(panel2);
//Here you setup your panels and your actionlisteners etc and when
//you wish for your second panel to show up just run the code below.
panel1.setVisible(false);
panel2.setVisible(true);
Obviously you first have to add both panels to your Jframe. Panel1 will be at first visible, as it is the one shown by default. Panel2 must be set to be invisible in the beginning.