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Layout Problem in Java - set a 20%opaque Panel on Bottom of JFrame

Well, actually I have a Layout problem in java Swing. I simply want to add a JPanel on the bottom of a Frame - a coding snipplet that might be done with every web based language in about 5 Minutes. Not so in Java. I tried to add a jPanel to a jFrame, that Contains a jContentPane, set the size of the jPanel to what I need and to repaint and revalidate the jFrame, as well as setting the LayOutManager to null.
Java shows me in this case a full-width jPanel, that fills my whole jFrame.
Therefore I tried another approach: I divided my jPanel in a fully transparent jPanel on top and a 20%opaque jPanel on the bottom. Still it didn't work out as expected.
Since then I tried to resize the child jPanels of my new Panel and the Panel as well and tried to repaint and revalidate the jFrame. Without any effect.
Despite of my efforts, java still shows me a full sized 20%opaque jPanel on the whole jFrame, that now contains another 20%opaque jPanel on Top.
I know that this whole problem is caused by the LayoutManager, Java useless per Default. However, it is not an option to set the LayoutManager to null or even change the LayoutManager of our jFrame, because that would lead us to refactor the whole functionality of our tiny app we worked on for several weeks.
public void showUndoPanel() {
System .out.println("Show Undo Panel");
JPanel myPanel = new JPanel(null);
JPanel glassPanel = new JPanel();
JPanel ContentPanel = new JPanel();
JLabel myJLabel = new JLabel("Great Job!");
myPanel.setBackground(new Color(255,122,122,100));
glassPanel.setSize(650, 550);
glassPanel.setBackground(new Color(255,122,122,100));
myPanel.add(glassPanel);
ContentPanel.setSize(650, 30);
ContentPanel.setBackground(new Color(255,122,122,20));
ContentPanel.add(myJLabel);
myPanel.revalidate();
myPanel.repaint();
undoPanel = myPanel;
myJFrame.add(undoPanel);
myJFrame.revalidate();
}
What I expected:
What it actually does:

Well, I solved the problem by using a BoxLayoutManager and a RigidArea. In case if anyone else may encounter that problem again in the future, I decided to provide the code for this simple solution.
public void showUndoPanel() {
System .out.println("Show Undo Panel");
JPanel myPanel = new JPanel(null);
JPanel glassPanel = new JPanel();
JPanel ContentPanel = new JPanel();
JLabel myJLabel = new JLabel("Great Job!");
myPanel.setBackground(new Color(255,255,255,0));
myPanel.setLayout(new BoxLayout(myPanel, BoxLayout.PAGE_AXIS));
glassPanel.setSize(650, 650);
glassPanel.setBounds(0,0,650,550);
glassPanel.setBackground(new Color(255,122,122,0));
myPanel.add(glassPanel);
myPanel.add(Box.createRigidArea(new Dimension(0,450)));
ContentPanel.setSize(650, 30);
ContentPanel.setBounds(0,750,650,30);
ContentPanel.setBackground(new Color(255,122,122,20));
ContentPanel.add(myJLabel);
myPanel.add(ContentPanel);
myPanel.revalidate();
myPanel.repaint();
undoPanel = myPanel;
myJFrame.add(undoPanel);
myJFrame.revalidate();
}
Now it behaves as expected:

BorderLyout would make it easier to implement.
Note the comments in the following mre:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Main {
private static JFrame myJFrame;
public static void main(String[] args) {
myJFrame = new JFrame();
myJFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
myJFrame.setLocationRelativeTo(null);
showUndoPanel();
myJFrame.pack();
myJFrame.setVisible(true);
}
public static void showUndoPanel() {
JPanel myPanel = new JPanel();
myPanel.setBackground(new Color(255,255,255,0));
myPanel.setLayout(new BorderLayout());
JPanel glassPanel = new JPanel(); //uses FlowLayout by default
//glassPanel.setSize(650, 650); //use preferred size
glassPanel.setPreferredSize(new Dimension(650, 650));
//glassPanel.setBounds(0,0,650,550); //no need to set bounds. bounds are set by the layout manager
glassPanel.setBackground(new Color(255,122,122,0));
myPanel.add(glassPanel, BorderLayout.CENTER);
JPanel contentPanel = new JPanel(); //uses FlowLayout by default
//contentPanel.setSize(650, 30);//use preferred size
contentPanel.setPreferredSize(new Dimension(650, 30));
//contentPanel.setBounds(0,750,650,30); //no need to set bounds. bounds are set by the layout manager
contentPanel.setBackground(new Color(255,122,122,20));
JLabel myJLabel = new JLabel("Great Job!");
contentPanel.add(myJLabel);
myPanel.add(contentPanel, BorderLayout.SOUTH);
myJFrame.add(myPanel);
}
}

Java component deployment using JPanel

I wanted components deployment like this picture:
I wrote a code that makes two JPanel in a JFrame and puts components JPanel on left side. I set Frame Layout to BorderLayout and Each panel's Layout to FlowLayout. However, result was not what I wanted. Even List is not appear.
Result picture:
Can you tell me what to do?
There is a code below.
package com.java.APISearch;
import java.awt.*;
import javax.swing.*;
import javax.swing.JPanel;
public class MainFrame extends JFrame {
JPanel search;
JPanel result;
JLabel ksLb;
JTextField ksTf;
JButton ksOK;
JCheckBox choicePackage;
JCheckBox choiceClass;
JCheckBox choiceFunc;
JTextField dsTf;
JButton dsOK;
JLabel rcLb;
JList<String> rcList;
JTextField resultTf;
Container contentPane;
public MainFrame(String title) {
super(title);
Toolkit tk = Toolkit.getDefaultToolkit();
Dimension screenSize = tk.getScreenSize();
setLocation(screenSize.width/2 - 300, screenSize.height/2 - 200);
setSize(new Dimension(600, 400));
setResizable(false);
setLayout(new BorderLayout());
search = new JPanel();
result = new JPanel();
search.setLayout(new FlowLayout(FlowLayout.LEFT));
search.setSize(new Dimension(300,400));
result.setLayout(new FlowLayout());
result.setSize(new Dimension(300,400));
contentPane = getContentPane();
contentPane.add(search, BorderLayout.WEST);
contentPane.add(result, BorderLayout.EAST);
ksLb = new JLabel("키워드 검색");
ksTf = new JTextField(20);
ksOK = new JButton("검색");
search.add(ksLb);
search.add(ksTf);
search.add(ksOK);
choicePackage = new JCheckBox("package");
choiceClass = new JCheckBox("class");
choiceFunc = new JCheckBox("function");
dsTf = new JTextField(20);
dsOK = new JButton("검색");
search.add(choicePackage);
search.add(choiceClass);
search.add(choiceFunc);
search.add(dsTf);
search.add(dsOK);
rcLb = new JLabel("recent search");
rcList = new JList<String>();
search.add(rcLb);
search.add(rcList);
}
}

The common strategy to solve complex computing tasks, is to break them into small, well defined manageable tasks. Divide and conquer.
This also applies to gui: break the design into small, easy to layout containers.In this case, for example start by dividing the design into two areas:
Serach panel added to JFrame's NORTH, and a main panel added to JFrame's CENTER. The main panel is a container for all other gui components. See more info in the code.
Here is a skeleton to demonstrate the strategy. Note the comments :
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class MainFrame extends JFrame {
public MainFrame(String title) {
super(title);
setSize(new Dimension(600, 400));
setResizable(false);
//setLayout(new BorderLayout());// no need. its the default for JFrame
JPanel search = new JPanel();
search.setLayout(new FlowLayout(FlowLayout.LEFT));
//search.setSize(new Dimension(300,400)); //let layout manager set size
//set preferred size if needed
JLabel ksLb = new JLabel("Search:");
JTextField ksTf = new JTextField(20);
JButton ksOK = new JButton("Click Me");
search.add(ksLb);
search.add(ksTf);
search.add(ksOK);
add(search, BorderLayout.NORTH); //add search to content pane
//construct a container to hold all the rest
//set border layout to it
JPanel mainPanel = new JPanel(new BorderLayout());
//add content to mainPanel:
//add result to NORTH
//add a JPanel to hold list and label to CENTER
add(mainPanel, BorderLayout.CENTER);//main to content pane
setVisible(true);
}
}
More examples of applying this strategy: 1 2 and 3

To make thing like this, use NetBeans (or some other tool that will help you create layout).
In NetBeans, getting something like you want takes ~5 minutes. It's really easier comparing to writing code for yourself.
In my personal opinion, GridBagLayout is the best thing when it comes to most of Swing based components. You can easily take control over each and every cell (whether it should grow or not, how anchors should behave, whether components should fill cell or not, etc.).
Take a look here: https://docs.oracle.com/javase/tutorial/uiswing/layout/gridbag.html
If you don't know which layout would suit you best, you can always take a look here:
https://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html
For NetBeans tutorial, take a look here: https://netbeans.org/kb/docs/java/quickstart-gui.html

Layout - Relative to screensize

So I am a computer science student and I've finished my first year. I wanted to create a simple program and I realized that I am so tired of using no layout;
this.setLayout(null);
It is so tiresome to add bounds to every single component. Well, I have been using JPanel components and GridLayout a lot, which have made my work a bit easier. But I am tired of it.
I care very much about the look of the GUI I make and use almost half the time programming to make the GUI look good before I start adding the functionality of the code. By not using a layout and adding bounds I am forced to setResizable(false) because it looks bad if I change the size of the JFrame.
I've been searching a bit, and I know of BorderLayout, and FlowLayout, but I don't like them. Is there any Layout that keeps the relative size of the components with respect to the size of the window?
For example I want to make a simple program that looks like this: (Quick sketch in Photoshop)
I can easily make this with 3 panels, but as I said, if I change the size of the frame everything stays in place instead of being relative to the window-size.
Can you guys help me?

This design looks for me to fit the BorderLayout, where in the NORTH you have the values that changes the CENTER you have the main part, and the SOUTH you have the buttons.
Link to the Oracle Border Layout
You can apply this BorderLayout to the JFrame, then create 3 JPanels for each of the NORTH,CENTER and SOUTH sections. If you want to use responsive design for the components and panels, take a look at GridBagLayout which is much more flexible than the GridLayout

Layout management is a very complex problem, I don't think people really appreciate just how complex it really is.
No one layout is ever going to achieve everything your want, in most cases, you will need to resort to two or more layouts, especially as your requirements become more complex.
For example, the following is simply a BorderLayout at the base and the buttons on a JPanel using a FlowLayout
Which is achieved by using
JList listOfThings = new JList(...);
JTextField tf = new JTextField();
JButton add = new JButton("Add");
JButton delete = new JButton("Delete");
JButton go = new JButton("Go...");
JPanel buttons = new JPanel();
buttons.add(add);
buttons.add(delete);
buttons.add(go);
add(new BorderLayout());
add(tf, BorderLayout.NORTH);
add(new JScrollPane(listOfThings));
add(buttons, BorderLayout.SOUTH);
For more complex layouts, I would consider using something like GridBagLayout. You may also want to consider MigLayout as an alternative
Take a look at Laying Out Components Within a Container for more details about using layout managers

I'd like to use the combination of BorderLayout and BoxLayout. BorderLayout let me put the component based on their relative location's relation and BoxLayout let me manage the subtle distance ( create some white space). You can use component.setBorder(BorderFactory.createEmptyBorder(top, left, bottom, right)); to achieve this goal too.
Here is a demo and hope it can help you.
import java.awt.BorderLayout;
import java.awt.Color;
import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
public class LayoutTest{
private JTextField jTextField;
public void createUI(){
JFrame frame = new JFrame("Layout Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(true);
JPanel mainPanel = new JPanel();
mainPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));
mainPanel.add(new TextFieldPanel());
mainPanel.add(Box.createVerticalStrut(8));
mainPanel.add(new ListPanel());
mainPanel.add(Box.createVerticalStrut(8));
mainPanel.add(new ButtonPanel());
frame.add(mainPanel,BorderLayout.CENTER);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
LayoutTest layoutTest = new LayoutTest();
layoutTest.createUI();
}
#SuppressWarnings("serial")
class TextFieldPanel extends JPanel{
public TextFieldPanel(){
setLayout(new BorderLayout());
jTextField = new JTextField();
jTextField.setEditable(false);
add(jTextField,BorderLayout.CENTER);
}
}
#SuppressWarnings("serial")
class ListPanel extends JPanel implements ListSelectionListener{
private JList<String> list;
public ListPanel(){
setLayout(new BorderLayout());
String stringArr[] = new String[30];
for (int i = 0; i < 30; i++) {
stringArr[i] = "JList :This line is item" + i;
}
list = new JList<String>(stringArr);
JScrollPane scrollPane = new JScrollPane(list);
add(scrollPane,BorderLayout.CENTER);
setBackground(new Color(211,211,211));
list.addListSelectionListener(this);
}
#Override
public void valueChanged(ListSelectionEvent e) {
// TODO Auto-generated method stub
jTextField.setText(list.getSelectedValue());
}
}
#SuppressWarnings("serial")
class ButtonPanel extends JPanel{
public ButtonPanel(){
JButton button1 = new JButton("Button1");
JButton button2 = new JButton("Button2");
JButton button3 = new JButton("Button3");
setLayout(new BorderLayout());
add(button1,BorderLayout.WEST);
add(button2,BorderLayout.CENTER);
add(button3,BorderLayout.EAST);
}
}
}
Here is the effect:
You can use BoxLayout for ButtonPanel if you don't want to let the button's size change.
#SuppressWarnings("serial")
class ButtonPanel extends JPanel{
public ButtonPanel(){
JButton button1 = new JButton("Button1");
JButton button2 = new JButton("Button2");
JButton button3 = new JButton("Button3");
setLayout(new BoxLayout(this, BoxLayout.X_AXIS));
add(button1);
add(Box.createHorizontalStrut(8));
add(button2);
add(Box.createHorizontalStrut(8));
add(button3);
}
}
And the effect is like this:
For more infomation about using BoxLayout to generate whitespace, you can refer to https://stackoverflow.com/a/22525005/3378204

Try GridBagLayout.
Your sketch is actually quite close to the one of the examples in the official tutorial.

HVLayout keeps the relative size of the components with respect to the size of the window, that is, if you configure components to have a relative size (e.g. buttons usually do not grow or shrink - they stick to their preferred size). This SO question was one of the motivations for me to push HVLayout to a release and a screenshot is included (showing big window size, smalll size and preferred "default" size):
Source code for the window is in RelativeToWindowSize.java
A number of helper-classes from HVLayout are used to build the window, so I don't think it will be of much use here, but to get an impression, the "build window" part shown below:
public RelativeToWindowSize build() {
CSize cs = new CSize();
CForm form = new CForm(new VBox(new Insets(2, 4, 2, 4)), cs);
addTitledBorder(form.get(), "Vertical box", Color.BLACK);
form.add(new JScrollPane(
tfield = new JTextArea("Value that changes with value choosen from list.\nhttp://stackoverflow.com/questions/24462297/layout-relative-to-screensize/")
)).csize().setAreaSize(1.0f, 2.5f).fixedMinHeight().setMaxHeight(4.0f);
// tfield shows mono-spaced font by default.
tfield.setFont(SwingUtils.getUIFont());
form.add(new JScrollPane(vlist = new JList<String>(getListValues())))
.csize().setAreaSize(1.0f, 5.0f);
form.addChild(new HBox());
addTitledBorder(form.get(), "Horizontal box", Color.RED);
form.addChild(new HBox(SwingConstants.CENTER));
addTitledBorder(form.get(), "Centered box.", Color.BLUE);
form.add(createButton(cs, "Add"));
form.add(createButton(cs, "Modify"));
form.up();
form.addChild(new HBox(SwingConstants.TRAILING));
addTitledBorder(form.get(), "Trailing box", Color.GREEN);
form.add(createButton(cs, "Delete"));
setContentPane(form.getRoot());
pack();
setLocationByPlatform(true);
//applyComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
vlist.addListSelectionListener(this);
log.debug(getClass().getName() + " build.");
return this;
}
private Component createButton(CSize cs, String text) {
// For purpose of demo, let button shrink in width.
return cs.set(new TButton(text)).setFixed().shrinkWidth(0.33f).get();
}

Why won't my buttons appear when I run this JFrame?

I am trying to make a Rock, Paper, Scissors game and I have added 3 buttons to the frame, however when I launch the program two of the buttons don't appear until you hover over them, anyone have any idea why?
import javax.swing.*;
import java.awt.event.*;
import java.util.Random;
import java.awt.FlowLayout;
import javax.swing.JOptionPane;
public class RPSFrame extends JFrame {
public static void main(String [] args){
new RPSFrame();
}
public RPSFrame(){
JFrame Frame1 = new JFrame();
this.setSize(500,500);
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setTitle("Rock, Paper or Scissors game");
this.setLocationRelativeTo(null);
ClickListener cl1 = new ClickListener();
ClickListener cl2 = new ClickListener();
ClickListener cl3 = new ClickListener();
JPanel panel1 = new JPanel();
JLabel label1 = new JLabel("Result:");
panel1.setLayout(new FlowLayout(FlowLayout.CENTER, 25, 25));
this.add(panel1);
this.setVisible(false);
JPanel panel2 = new JPanel();
JButton Rock = new JButton("Rock");
Rock.addActionListener(cl1);
panel2.setLayout(new FlowLayout(FlowLayout.LEFT));
panel2.add(Rock);
this.add(panel2);
this.setVisible(true);
JPanel panel3 = new JPanel();
JButton Paper = new JButton("Paper");
Paper.addActionListener(cl2);
panel3.setLayout(new FlowLayout(FlowLayout.CENTER));
panel3.add(Paper);
this.add(panel3);
this.setVisible(true);
JPanel panel4 = new JPanel();
JButton Scissors = new JButton("Scissors");
Scissors.addActionListener(cl3);
panel4.setLayout(new FlowLayout(FlowLayout.RIGHT));
panel4.add(Scissors);
this.add(panel4);
this.setVisible(true);
}
private class ClickListener implements ActionListener{
public void actionPerformed(ActionEvent e){
if(e.getSource() == "Rock"){
int AI = new Random().nextInt(3) + 1;
JOptionPane.showMessageDialog(null, "I have been clicked!");
}
}
}
}

The setVisible(true) statement should be invoked AFTER all the components have been added to the frame.
You currently have two setVisible(...) statements, so you need to get rid of the first one.
Edit:
Took a second look at the code. You have multiple setVisible(...) statements. Get rid of them all except for the last one.
Don't create separate panels for each button. Instead you create one panel (called buttonPanel) for all the buttons. In your case you might use a horizontal BoxLayout. Add a button to the panel, then add glue then add a button, then add glue and then add your final button. Then add this buttonPanel to the NORTH of the frame. ie. this.add(buttonPanel, BorderLayout.NORTH). Read the section from the Swing tutorial on How to Use Box Layout for more information on how the layout works and on what glue is.

The problem is that JFrame has a default BorderLayout. When you just add(component) without specifying a BorderLayout.[POSITION] e.g add(panel, BorderLayout.SOUTH), then the component will get added to the CENTER. The problem with that is each POSITION can only have one component. So the only component you see id the last one you add.
Now I don't know after specifying the positions, if you will get your desired result. A BorderLayout may not be the right fit. But just to see a change, you can set the layout to GridLayout(0, 1) and you will see the component.
this.setLayout(new GridLayout(0, 1));
If this is not the result you want, then you should look over Laying out Components within a Container to learn the different layouts available to you.
Also as I pointed out in my comment
if(e.getSource() == "Rock"){
with the above, you are trying to compare an object (ultimately a button) with a String. Instead you will want to compare the actionCommand
String command = e.getActionCommand();
if("Rock".equals(command)){

Centering a JLabel on a JPanel

I'm using the NetBeans GUI builder to handle my layout (I'm terrible with LayoutManagers) and am trying to place a simple JLabel so that it is always centered (horizontally) inside its parent JPanel. Ideally, this would maintain true even if the JPanel was resized, but if that's a crazy amount of coding than it is sufficient to just be centered when the JPanel is first created.
I'm bad enough trying to handle layouts myself, but since the NetBeans GUI Builder autogenerates immutable code, it's been impossible for me to figure out how to do this centering, and I haven't been able to find anything online to help me.
Thanks to anybody who can steer me in the right direction!

Here are four ways to center a component:
import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;
class CenterComponent {
public static JLabel getLabel(String text) {
return getLabel(text, SwingConstants.LEFT);
}
public static JLabel getLabel(String text, int alignment) {
JLabel l = new JLabel(text, alignment);
l.setBorder(new LineBorder(Color.RED, 2));
return l;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JPanel p = new JPanel(new GridLayout(2,2,4,4));
p.setBackground(Color.black);
p.setBorder(new EmptyBorder(4,4,4,4));
JPanel border = new JPanel(new BorderLayout());
border.add(getLabel(
"Border", SwingConstants.CENTER), BorderLayout.CENTER);
p.add(border);
JPanel gridbag = new JPanel(new GridBagLayout());
gridbag.add(getLabel("GridBag"));
p.add(gridbag);
JPanel grid = new JPanel(new GridLayout());
grid.add(getLabel("Grid", SwingConstants.CENTER));
p.add(grid);
// from #0verbose
JPanel box = new JPanel();
box.setLayout(new BoxLayout(box, BoxLayout.X_AXIS ));
box.add(Box.createHorizontalGlue());
box.add(getLabel("Box"));
box.add(Box.createHorizontalGlue());
p.add(box);
JFrame f = new JFrame("Streeeetch me..");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setContentPane(p);
f.pack();
f.setLocationByPlatform(true);
f.setVisible(true);
}
});
}
}

By using Borderlayout, you can put any of JComponents to the CENTER area. For an example, see an answer to Stack Overflow question Get rid of the gap between JPanels. This should work.

Even with BoxLayout you can achieve that:
JPanel listPane = new JPanel();
listPane.setLayout(new BoxLayout(listPane, BoxLayout.X_AXIS ));
JLabel label = new JLabel();
listPane.add(Box.createHorizontalGlue());
listPane.add(label);
listPane.add(Box.createHorizontalGlue());
mKorbel's solution is perfect for your goal. Anyway I always like to suggest BoxLayout because it's very flexible.

Mara: "thanks for your response, however the NetBeans GUI Build uses GroupLayout and this is not overridable."
Not true! Right click anywhere inside JFrame (or any other GUI container) in NetBeans GUI builder and select "Set Layout". By default is selected "Free Design", which is Group layout, but you can select any other layout including Border layout as advised by mKorbel.

There's many ways to do this, depending on the layout manager(s) you use. I suggest you read the Laying Out Components Within a Container tutorial.
I believe the following will work, regardless of layout manager:
JLabel.setHorizontalAlignment(SwingConstants.CENTER)