Develop Reference

Swing JScrollPane resizing to fit the viewport panel

I tried a lot of layout managers but none could solve my problem:
I want the items in a scrollPane to keep their size (preferred or minimum) and not being resized (reduced) to fit the viewport Panel. Since if it is a JTextArea, and if the text area has blank space and it is bigger then the viewport, it would reduce it so the blank text area won't be shown. I want the blank text area to be shown for appearance issues.
Im stacking one item after another using BoxLayout, and it seems to me that for text areas the setMinimum method fails.
If the text area has blank space, then the scrollbar of the ScrollPane won't appear, instead it only appears it there are no blank space left.
Any solution?
JScrollPane materialPane = new FScrollPane();
this.materialPaneView = new TPanel();
this.materialPaneView.setMinimumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/2)));
this.materialPaneView.setLayout(new BoxLayout(this.materialPaneView, BoxLayout.Y_AXIS));
materialPane.setViewportView(materialPaneView);
materialPane.setMinimumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/2)));
for(Material mat: this.unit.getMaterial()){
this.addMaterial(mat);
}
centerPanel.add(sectionPane);
centerPanel.add(exercisePane);
centerPanel.add(materialPane);
this.add(upperPanel, BorderLayout.NORTH);
this.add(centerPanel, BorderLayout.CENTER);
public void addMaterial(Material mat){
JTextField matName = new JTextField(30);
JPanel fieldButtonPanel = new TPanel();
fieldButtonPanel.setLayout(new GridLayout(1,2));
JPanel fieldPanel = new TPanel(new FlowLayout(FlowLayout.LEFT));
JPanel deleteMatButtonPanel = new TPanel(new FlowLayout(FlowLayout.RIGHT));
matName.setText(mat.getName());
matName.setMaximumSize(new Dimension(FFont.def.getSize()*20, 30));
fieldPanel.add(matName);
JButton deleteMat = new JButton("Delete Material");
deleteMatButtonPanel.add(deleteMat);
fieldButtonPanel.add(fieldPanel);
fieldButtonPanel.add(deleteMatButtonPanel);
fieldButtonPanel.setAlignmentX(LEFT_ALIGNMENT);
JTextArea matText = new FTextArea(mat.getDesc(), (int)(WIDTH*0.95), (int)(HEIGHT/3.4));
matText.setMinimumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/3.5)));
/*matText.setMaximumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/3.4)));*/
matText.setText(mat.getDesc());
matText.setAlignmentX(LEFT_ALIGNMENT);
this.materialPaneView.add(fieldButtonPanel);
this.materialPaneView.add(matText);
matName.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
mat.setName(matName.getText());
}
});
HEIGHT and WIDTH are constants, and TPanel FScrollPane are my predefined transparent panels. The BoxLayout panel is the viewport of a scrollPane, and still, it would resize the text areas.

I am not sure i get what you are asking for so please tell me if i totally missed the point...
As far as i know the Viewport size is controlled by the component inside the JScrollPane and the JScrollPane size wont change no matter what happens to the viewport.
You either want to:
A) Resize the JScrollPane to the same size as it's content.
I would implement listeners to look for the content size change and resize the ScrollPane accordingly but you need to pay attention to resize the whole Hierarchy too.
B) You want to resize the viewport so that it fits in the JScrollPane? Y'know without scrollbars.
I had this problem and fixed it by using a ScrollablePanel component. Check this answer, follow the link to download the .class and use it to use a JPanel that resizes to fit the ScrollPane.
Those arent very detailed answers but i will need more information about what you are trying to do before expanding on it. And your code isnt complete, always share a code that we can CTRL+C/V and readily verify the problem in our end.

How to add image in Java Swing?

Help! How can I add image on my JFrame? This is my code
public class JavaApplication79 extends JFrame{
ImageIcon icon = new ImageIcon("Downloads/splash.jpg");
JLabel label = new JLabel(icon);
public JavaApplication79(){
add(label);
setLayout(null);
setSize(900,500);
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String args[]){
JavaApplication79 show = new JavaApplication79();
show.setVisible(true);
}
}

The problems start with the null layout. Because there is no layout to set the component size to it's preferred size, or any other size, the panel takes its default size of 0 x 0 pixels.
For 'top left' of frame I'd recommend FlowLayout.
For 'center' of frame - GridBagLayout is easy.
For 'centered & stretched' to fill the frame, GridLayout.
Learn about layouts in the Laying Out Components Within a Container lesson of the tutorial.
But an extra tip about combining layouts for different effects in different parts of the GUI. Use layout managers, or combinations of them along with layout padding and borders for white space.

Use BorderLayout to create two even columns

I'm trying to create a program using BorderLayout() that I want to look like this (but with even left right height and such)
although I am having trouble resizing the two JPanels (two boxes within the large box). At the moment my GUI looks like this,
I believe it is due to the CENTER still being there, I looked up on how to remove it but could not get it to work,
Question
Can can I edit this so that it will look like the top image.
package fuelstation;
import java.awt.*;
import java.util.*;
import javax.swing.*;
public class Fuelstation extends JFrame {
JButton btn1 = new JButton("Random Button");
public Fuelstation() {
JFrame frame = new JFrame("Fuel Station");
frame.setLayout(new BorderLayout());
frame.setResizable(false);
frame.setPreferredSize(new Dimension(500,350));
frame.setMaximumSize(new Dimension(500,350));
// Left Hand Side
JPanel lhs = new JPanel();
JTextArea tf_list = new JTextArea();
tf_list.setEditable(false);
tf_list.setWrapStyleWord(true);
tf_list.setText("This is a list of items");
lhs.add(tf_list);
tf_list.setSize(245, 325);
lhs.setBorder(BorderFactory.createTitledBorder("Left"));
// Left Hand Side End
// Right Hand Side
JPanel rhs = new JPanel();
rhs.setAlignmentX(Component.CENTER_ALIGNMENT);
rhs.setBorder(BorderFactory.createTitledBorder("Right"));
rhs.add(btn1);
tf_list.setSize(245, 325);
JPanel center = new JPanel();
center.setSize(0, 0);
// Right Hand Side End
frame.add(lhs, BorderLayout.WEST);
frame.add(center, BorderLayout.CENTER);
frame.add(rhs, BorderLayout.EAST);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
Fuelstation gui = new Fuelstation();
}
}

You need to drop the requirement to use a BorderLayout. The resizing policy for components when using a BorderLayout is stated in the class javadoc
The components are laid out according to their preferred sizes and the constraints of the container's size. The NORTH and SOUTH components may be stretched horizontally; the EAST and WEST components may be stretched vertically; the CENTER component may stretch both horizontally and vertically to fill any space left over.
By forcing your JFrame to a certain size
frame.setResizable(false);
frame.setPreferredSize(new Dimension(500,350));
frame.setMaximumSize(new Dimension(500,350));
your center component will take the extra width, as the EAST and WEST component will only stretch vertically.
So you need to use another LayoutManager. You can use the Visual guide to layout managers to get a grasp of the available LayoutManagers and their capabilities. That document states that a GridLayout would be a good candidate:
GridLayout simply makes a bunch of components equal in size and displays them in the requested number of rows and columns

JButton Appears on One Computer, But Not Others (BorderLayout)

I am new to Swing. I am building a JFrame with a JScrollPane inside it using Eclipse IDE. Inside of the JScrollPane is a JPanel in Border Layout. I tried to add a JButton (called "submitAnswers") to the JFrame using the code below, but for some reason the button only appears at the end of the frame on my computer, but not on other computers (my friend tried it on his Mac and I tried it on a separate Windows OS like mine). Some proposed solutions that I have tried and from other sites that have not worked include:
Use the pack() method. Reason: since the preferred size of the JPanel is much longer in height than the JFrame (hence I employed a JScrollPane), packing the JFrame only causes the text to be not visible on the desktop.
Place button on content JPanel. Reason: I don't know. It just wouldn't appear on another desktop computer or my friend's mac computer.
Use BorderLayout.SOUTH instead of BorderLayout.PAGE_END. Reason: There was absolutely no change. The button would still be visible on my computer, but invisible on others.
Place button directly on JFrame. Reason: I don't know.
In addition, my JFrame is nested within a static method; hence, I've only included the relevant code for the specific method I'm having issues with.
Has anyone had this issue before? I would really appreciate your insight.
Code:
public static void createTestPage() {
JFrame testFrame = new JFrame("testing...1,2,3");
//Customizes icon to replace java icon
try {
testFrame.setIconImage(ImageIO.read(new File("src/icon.png")));
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
//Centers location of introFrame to center of desktop
Dimension screenDimensions = Toolkit.getDefaultToolkit().getScreenSize();
testFrame.setLocation(screenDimensions.width / 16,screenDimensions.height / 14);
//Size and display the introFrame.
Insets insets = testFrame.getInsets();
//Format size of screen itself
testFrame.setSize(1200 + insets.left + insets.right,
400 + insets.top + 250 + insets.bottom);
//Temporarily set screen so that it cannot be resized
testFrame.setResizable(false);
//Set background color of testFrame
testFrame.getContentPane().setBackground(new Color(75, 0, 130));
testFrame.setLayout(new BorderLayout());
//Set layout of testFrame
testFrame.setLayout(new BorderLayout(10, 1));
//Test content
JPanel testContentPanel = new JPanel();
testContentPanel.setBackground(new Color(75, 0, 130));
testContentPanel.setSize(new Dimension(900,2060));
testContentPanel.setPreferredSize(new Dimension(900, 2060));
//Test content pane layout
testContentPanel.setLayout(new BoxLayout(testContentPanel, BoxLayout.PAGE_AXIS));
//Create panel to hold instructions text
JPanel instructionsPanel = new JPanel();
instructionsPanel.setBackground(new Color(75, 0, 130));
instructionsPanel.setLayout(new BorderLayout(10,1));
//Create JPanel for submit answers button
JPanel submitAnswersPanel = new JPanel(new BorderLayout());
submitAnswersPanel.setBackground(new Color(75, 0, 130));
submitAnswersPanel.setVisible(true);
//Create button to submit personality test answers
JButton submitAnswers = new JButton("Submit Answers");
submitAnswers.setVisible(true);
submitAnswers.setBorder(new EmptyBorder(10, 400, 10, 400));
//Add submitAnswers button to panel
submitAnswersPanel.add(submitAnswers);
//Add submitAnswersPanel to test content panel
testContentPanel.add(submitAnswersPanel);
//Create scroll pane to allow for scrollable test (contents cannot fit one page)
JScrollPane testScrollPane = new JScrollPane();
testScrollPane.setViewportView(testContentPanel);
//Get rid of horizontal scroll bar and add vertical scrollbar
testScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
testScrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
//Speed up scrolling
testScrollPane.getVerticalScrollBar().setUnitIncrement(16);
testFrame.add(testScrollPane);
//Experiment to show button
testFrame.setVisible(true);
}

I've refactored your code a little to use method to create the individual components of the GUI. You can find the full code at this ideone link
What I saw when I first copied your code to my machine was that the only thing visible was the button. So I create all the components in their own methods and then added them to the frame and panels using the Border Layout. This then enabled me to put the instructions in the NORTH sections, the button in the SOUTH section and then the main bits would go in the CENTER section.
One thing to note about the sections: (From the documentation)
The components are laid out according to their preferred sizes and the constraints of the container's size. The NORTH and SOUTH components may be stretched horizontally; the EAST and WEST components may be stretched vertically; the CENTER component may stretch both horizontally and vertically to fill any space left over.
So you should add the component you want to scale in size to the CENTER section.
My main method now looks like this:
public static void main(final String[] args) {
final JButton submitAnswers = createSubmitAnswersButton();
final JPanel instructionsPanel = createInstructionsPanel();
final JPanel testContentPanel = createContentPanel();
testContentPanel.add(instructionsPanel, BorderLayout.NORTH);
testContentPanel.add(submitAnswers, BorderLayout.SOUTH);
final JScrollPane scrollingContentPane = createScrollPaneFor(testContentPanel);
final JFrame testFrame = createJFrame();
testFrame.add(scrollingContentPane, BorderLayout.CENTER);
testFrame.setVisible(true);
}

How to layout multiple panels on a jFrame? (java)

I am in the process of making my own java socket game. My game is painting alright to the full screen (where it says "paint graphics here", but im painting to the whole jframe at the moment). I want to add a textbox with a scroll bar for displaying only text, not taking any input and another textbox to take text inputs from the user and then a button to send the text, for chat purposes. But onto my question, how do I even start to lay this out? I understand I need a layout, but can someone help me on this? Here is my code at the moment (this code only sets up painting to the whole screen at the moment, need to divide the screen up now like I have in the picture above):
public class Setup extends JFrame implements Runnable{
JPanel panel;
JFrame window;
public Setup(Starter start, JFrame window){
window.setSize(600,500);
window.setLocationRelativeTo(null);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setResizable(false);
panel = new Display(start);
this.window = window;
}
public void run(){
window.getContentPane().add(panel);
window.setBackground(Color.BLACK);
window.setVisible(true);
}
}
"new Display(start)" - this extends jpanel, its basically where I paint everything graphics wise.
In addition, I've seen people add in different panels but I cant have them be the same size. Like in the picture, the "paint graphics here" panel is the biggest one, and so on.

The JPanel is actually only a container where you can put different elements in it (even other JPanels). So in your case I would suggest one big JPanel as some sort of main container for your window. That main panel you assign a Layout that suits your needs ( here is an introduction to the layouts).
After you set the layout to your main panel you can add the paint panel and the other JPanels you want (like those with the text in it..).
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));
JPanel paintPanel = new JPanel();
JPanel textPanel = new JPanel();
mainPanel.add(paintPanel);
mainPanel.add(textPanel);
This is just an example that sorts all sub panels vertically (Y-Axis). So if you want some other stuff at the bottom of your mainPanel (maybe some icons or buttons) that should be organized with another layout (like a horizontal layout), just create again a new JPanel as a container for all the other stuff and set setLayout(new BoxLayout(mainPanel, BoxLayout.X_AXIS).
As you will find out, the layouts are quite rigid and it may be difficult to find the best layout for your panels. So don't give up, read the introduction (the link above) and look at the pictures – this is how I do it :)
Or you can just use NetBeans to write your program. There you have a pretty easy visual editor (drag and drop) to create all sorts of Windows and Frames. (only understanding the code afterwards is ... tricky sometimes.)
EDIT
Since there are some many people interested in this question, I wanted to provide a complete example of how to layout a JFrame to make it look like OP wants it to.
The class is called MyFrame and extends swings JFrame
public class MyFrame extends javax.swing.JFrame{
// these are the components we need.
private final JSplitPane splitPane; // split the window in top and bottom
private final JPanel topPanel; // container panel for the top
private final JPanel bottomPanel; // container panel for the bottom
private final JScrollPane scrollPane; // makes the text scrollable
private final JTextArea textArea; // the text
private final JPanel inputPanel; // under the text a container for all the input elements
private final JTextField textField; // a textField for the text the user inputs
private final JButton button; // and a "send" button
public MyFrame(){
// first, lets create the containers:
// the splitPane devides the window in two components (here: top and bottom)
// users can then move the devider and decide how much of the top component
// and how much of the bottom component they want to see.
splitPane = new JSplitPane();
topPanel = new JPanel(); // our top component
bottomPanel = new JPanel(); // our bottom component
// in our bottom panel we want the text area and the input components
scrollPane = new JScrollPane(); // this scrollPane is used to make the text area scrollable
textArea = new JTextArea(); // this text area will be put inside the scrollPane
// the input components will be put in a separate panel
inputPanel = new JPanel();
textField = new JTextField(); // first the input field where the user can type his text
button = new JButton("send"); // and a button at the right, to send the text
// now lets define the default size of our window and its layout:
setPreferredSize(new Dimension(400, 400)); // let's open the window with a default size of 400x400 pixels
// the contentPane is the container that holds all our components
getContentPane().setLayout(new GridLayout()); // the default GridLayout is like a grid with 1 column and 1 row,
// we only add one element to the window itself
getContentPane().add(splitPane); // due to the GridLayout, our splitPane will now fill the whole window
// let's configure our splitPane:
splitPane.setOrientation(JSplitPane.VERTICAL_SPLIT); // we want it to split the window verticaly
splitPane.setDividerLocation(200); // the initial position of the divider is 200 (our window is 400 pixels high)
splitPane.setTopComponent(topPanel); // at the top we want our "topPanel"
splitPane.setBottomComponent(bottomPanel); // and at the bottom we want our "bottomPanel"
// our topPanel doesn't need anymore for this example. Whatever you want it to contain, you can add it here
bottomPanel.setLayout(new BoxLayout(bottomPanel, BoxLayout.Y_AXIS)); // BoxLayout.Y_AXIS will arrange the content vertically
bottomPanel.add(scrollPane); // first we add the scrollPane to the bottomPanel, so it is at the top
scrollPane.setViewportView(textArea); // the scrollPane should make the textArea scrollable, so we define the viewport
bottomPanel.add(inputPanel); // then we add the inputPanel to the bottomPanel, so it under the scrollPane / textArea
// let's set the maximum size of the inputPanel, so it doesn't get too big when the user resizes the window
inputPanel.setMaximumSize(new Dimension(Integer.MAX_VALUE, 75)); // we set the max height to 75 and the max width to (almost) unlimited
inputPanel.setLayout(new BoxLayout(inputPanel, BoxLayout.X_AXIS)); // X_Axis will arrange the content horizontally
inputPanel.add(textField); // left will be the textField
inputPanel.add(button); // and right the "send" button
pack(); // calling pack() at the end, will ensure that every layout and size we just defined gets applied before the stuff becomes visible
}
public static void main(String args[]){
EventQueue.invokeLater(new Runnable(){
#Override
public void run(){
new MyFrame().setVisible(true);
}
});
}
}
Please be aware that this is only an example and there are multiple approaches to layout a window. It all depends on your needs and if you want the content to be resizable / responsive. Another really good approach would be the GridBagLayout which can handle quite complex layouting, but which is also quite complex to learn.

You'll want to use a number of layout managers to help you achieve the basic results you want.
Check out A Visual Guide to Layout Managers for a comparision.
You could use a GridBagLayout but that's one of the most complex (and powerful) layout managers available in the JDK.
You could use a series of compound layout managers instead.
I'd place the graphics component and text area on a single JPanel, using a BorderLayout, with the graphics component in the CENTER and the text area in the SOUTH position.
I'd place the text field and button on a separate JPanel using a GridBagLayout (because it's the simplest I can think of to achieve the over result you want)
I'd place these two panels onto a third, master, panel, using a BorderLayout, with the first panel in the CENTER and the second at the SOUTH position.
But that's me