I wrote the following code which is a simple window with a JLabel header at the top. The code is as follows:
import java.awt.Color;
import java.awt.Font;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
public class Main extends JFrame {
private static final long serialVersionUID = 1L;
public static void main(String[] args) {
init();
}
public Main() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
int WIDTH = 500;
int HEIGHT = 500;
setBackground(Color.LIGHT_GRAY);
setSize(WIDTH, HEIGHT);
setTitle("New Window");
setLocationRelativeTo(null);
JPanel pane = new JPanel();
pane.setOpaque(false);
setContentPane(pane);
pane.setLayout(null);
JLabel title = new JLabel("New Window", SwingConstants.CENTER);
title.setFont(new Font("Neuropol", Font.PLAIN, 22));
title.setSize(WIDTH, 20);
title.setBorder(BorderFactory.createLineBorder(Color.black));
pane.add(title);
}
static void init() {
Main frame = new Main();
frame.setVisible(true);
}
}
I'm having a weird issue with it though. As you can see I set the width of the JLabel to the same width as the JFrame (and therefore the same width as the JPanel), but for some reason, the label goes past the right edge of the Frame. The width of the frame is 500, but I have to set the JLabel to a width of 483 in order for the border to be within the JFrame. I've been over and over this, but can't see anything wrong. Does anybody see my mistake here?
I set the width of the JLabel to the same width as the JFrame
But the JFrame width includes the "decorations" of the frame, like the Border.
I have to set the JLabel to a width of 483 in order for the border to be within the JFrame.
No, 483 will make the label too big for the frame. The Borders of the frame are not 17 pixels. I think the Borders are 4 or 5 pixels each depending on the LAF.
So this is another reason why you should NOT be using a null layout as hardcoding a value for one LAF may not work on another LAF.
Also, what happens if the user resizes the frame wider? Now the label will not go to the end. Use a Layout Manager do design dynamic GUI's that adapt to changes as the user resizes the frame.
The easiest solution is to just use the default BorderLayout of content pane of the frame. Then you add your label to the PAGE_START.
add(title, BorderLayout.PAGE_START);
There is also no reason to create a content pane. The frame already has a JPanel which uses a BorderLayout.
Read the Swing tutorial on Layout Managers for more information and working examples. Download the demos code and use them as a starting point for your code. The demo code will show you how to better structure your code to follow Swing conventions.
Related
Why is my JLabel text not aligned to the left or center? Is the FlowLayout the issue?
Both of the texts are just appearing at the top, next to each other and I can't fix this.
Main Class
public static void main(String[] args) {
simpleGui SG = new simpleGui();
SG.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
SG.setSize(1000,1000);
SG.setVisible(true);
}
Constructor class
public class simpleGui extends JFrame{
private JLabel label1;
private JLabel label2;
simpleGui(){
//title bar
super("Simple GUI");
setLayout(new FlowLayout());
label1 = new JLabel("I'm a label in the window");
label1.setVerticalTextPosition(SwingConstants.BOTTOM);
add(label1);
label2 = new JLabel("Label2");
label2.setHorizontalTextPosition(SwingConstants.LEFT);
add(label2);
}
}
Refer to Laying Out Components Within a Container which is a lesson in the Creating a GUI With Swing trail of Oracle's Java tutorials.
The javadoc for method setVerticalTextPosition, of class JLabel states the following:
Sets the vertical position of the label's text, relative to its image.
A JLabel can contain both text and an image. The image is also referred to as an icon. Since the JLabel in your code contains only text, calling this method does nothing. The same applies for method setHorizontalTextPosition.
A layout manager is responsible for placing a JComponent within its parent container. FlowLayout, by default, places the components in the top, center part of the container (which is JPanel in your code) and gives them their preferred size. (Refer to method getPreferredSize in class javax.swing.JComponent)
I suggest that you put a border around each component so that you can see how much space each one actually takes up. In the below screen capture, I added a red border to the [content pane of the] JFrame, a cyan border around label1 and a blue border around label2.
I assume that you want label1 to appear at the bottom of the content pane and label2 to appear at the left side. Therefore I think that the default layout manager is appropriate. The default layout manager is BorderLayout.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
public class SimpleGui extends JFrame {
private JLabel label1;
private JLabel label2;
public SimpleGui() {
super("Simple GUI");
((JPanel) getContentPane()).setBorder(BorderFactory.createLineBorder(Color.red));
label1 = new JLabel("I'm a label in the window", SwingConstants.CENTER);
label1.setBorder(BorderFactory.createLineBorder(Color.cyan));
add(label1, BorderLayout.PAGE_END); // changed
label2 = new JLabel("Label2");
label2.setBorder(BorderFactory.createLineBorder(Color.blue));
add(label2, BorderLayout.LINE_START); // changed
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
SimpleGui sg = new SimpleGui();
sg.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
sg.setSize(1000,1000);
sg.setVisible(true);
});
}
}
This is how it looks when I run the above code.
Note that BorderLayout gives the bottom component the same width as the content pane as well as its preferred height while the left component is given its preferred width but its height matches the height of the content pane. Refer to the tutorial I linked to at the start of this answer.
Since the width of label1 is greater than the width of the text it contains, I explicitly set the horizontal alignment of label1 to CENTER. By default it is LEFT. The alignment only affects the display when the width of the JLabel is larger than the width of its text.
I recommend that you go through the entire Creating a GUI With Swing trail in Oracle's Java tutorials.
I've updated your code a bit, I changed the classname to include java naming conventions and I've stuck with the default BorderLayout. I think this is what you're after judging by the names of your constants.
import javax.swing.*;
import java.awt.*;
public class SimpleGui extends JFrame{
private JLabel label1;
private JLabel label2;
SimpleGui(){
//title bar
super("Simple GUI");
//setLayout(new FlowLayout());
label1 = new JLabel("I'm a label in the window");
label1.setVerticalTextPosition(SwingConstants.BOTTOM);
add(label1, BorderLayout.SOUTH);
label2 = new JLabel("Label2");
label2.setHorizontalTextPosition(SwingConstants.LEFT);
add(label2, BorderLayout.WEST);
}
public static void main(String[] args) {
SimpleGui SG = new SimpleGui();
SG.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
SG.setSize(1000,1000);
SG.setVisible(true);
}
}
The FlowLayout is going to position things differently and you cannot just say, "you're at the top" and "you're at the left".
What you perceive: Regardless of the calls setVerticalTextPosition() or setHorizontalTextPosition() the text is always at the same location. But your calls actually had some effect that you just did not see.
The reason is that there are two positioning algorithms at the same time:
Positioning the label within the frame
You asked FlowLayout to take care. FlowLayout will simply ask the components about their preferred size, then place one besides the other just as you would expect characters or words to show up besides each other in an editor. Not that at this time each label was sized to it's preferred size.
Positioning the text within the label
When the label is asked about it's preferred size, it will give the minimum size necessary to render the configured text with the configured font. This way the information can be rendered comfortably without clipping off any information.
Later, when the label is asked to render the text, it will try follow your settings setVerticalTextPosition() or setHorizontalTextPosition(). But since there is no excess space within the label, doing it left-aligned or right-aligned or top-aligned or bottom aligned all ends up at the same coordinate.
Getting out of this
Either accept that the labels use their minimum size and you take care that the labels themselves are positioned correctly (GridBagLayout is very powerful in this respect), or resize the labels by setting a minimum and/or preferred size on them, then watch how your text positioning works.
The text positioning can be seen very nicely if you use BorderLayout and add the label in the center position. But this typically will work for one component only.
private void setupGUI(){
// Setup Frame
f = new JFrame("Shape Image Generator");
f.setBounds(500, 150, 450, 350);
f.setLayout(new GridLayout(8,1));
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent windowEvent){
System.exit(0);
}
});
}
I create the frame above, then 8 panels. I create various components and add them to the panels and everything works fine. Until I created an ImageIcon and added it to a label and added that label to the 8th panel. The image used is 140x129 pixels. The problem is, only the top.... maybe 1/4 of the image is showing. If I change the frames dimensions in the code, more empty space is created between each panel, but only a slight bit more of the image is shown, so the image is still off of the screen. I'd say the window is easily adding 10 pixels of spacing for every 1 more pixel of the image it shows. If I drag the corners of the window to expand it, the same thing happens. If the window is maximized I still can only see a little over half of my now very stretched image.
Things I tried:
None of my components have preferred dimensions set, but I tried setting a preferred dimension for the label then panel that contains the ImageIcon and it only added the difference between the image and preferred size in gray space above the image, pushing it further offscreen. So, I undid that.
Adding the label containing the ImageIcon to a different panel which was not the 8th and last panel, in this case, the image is still cut off, but at the point that it gets cut off, the components on the panel underneath it appear (over top of the background coloring which cuts off the image).
Exhaustively Googling this situation with about 30 different ways of phrasing it and not finding a solution.
(row1 - row8 are JPanels, I didn't include the coding for them)
ImageIcon iconStart = createImageIcon("/images/ShapeClipart.png", "Shapes");
JLabel imgLabel = new JLabel();
row8.add(imgLabel);
// Add image to image label
imgLabel.setIcon(iconStart);
// Add panels to frame
f.add(row1);
f.add(row2);
f.add(row3);
f.add(row4);
f.add(row5);
f.add(row6);
f.add(row7);
f.add(row8);
f.setVisible(true);
Window at execution
Window when stretched
edit:
adding f.pack() makes a very tall skinny window (the windows height taller than my screen) but it still looks like when I manually expand the window (empty space between panels, image partially offscreen), even if I take out f.setBounds and only use f.setLocation.
You are using a GridLayout. This gives all of the enclosed panels the same amount of space. In this case it is a vertical grid.
You should probably use something a bit different. I might try a BorderLayout in the JFrame and put the a panel containing the top seven panels (in a GridLayout) into the CENTER, and then put the JLabel into the SOUTH portion of the JFrame.
There are other ways to lay it out, but this is the first I could think of.
GridLayout makes each cell in the grid the same size and the size of each cell is determined by the largest Component contained in the grid.
In your code, the icon is the largest component and you also have only one column in your grid so every row has the same height as your icon.
Since you also limit the size of your JFrame by calling method setBounds(), the Swing infrastructure cuts off the icon so that all the components fit into the bounds you specified.
One alternative, but not the only one, is to use BoxLayout since it uses the preferred size of each of its contained components.
Here is a sample GUI that matches the screen capture that you posted and uses BoxLayout.
import static javax.swing.WindowConstants.EXIT_ON_CLOSE;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.net.URL;
import javax.swing.BoxLayout;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JTextField;
public class Shapes23 implements Runnable {
private JFrame frame;
#Override // java.lang.Runnable
public void run() {
showGui();
}
private JPanel createEighthRow() {
JPanel eighthRow = new JPanel();
URL url = getClass().getResource("paint-bursht.jpg");
Icon ico = new ImageIcon(url);
JLabel label = new JLabel(ico);
eighthRow.add(label);
return eighthRow;
}
private JPanel createFifthRow() {
JPanel fifthRow = new JPanel();
JTextField textField = new JTextField(20);
fifthRow.add(textField);
return fifthRow;
}
private JPanel createFirstRow() {
JPanel firstRow = new JPanel();
JLabel label = new JLabel("2D Shapes");
firstRow.add(label);
return firstRow;
}
private JPanel createFourthRow() {
JPanel fourthRow = new JPanel();
fourthRow.add(createRadioButton("Sphere"));
fourthRow.add(createRadioButton("Cube"));
fourthRow.add(createRadioButton("Cone"));
fourthRow.add(createRadioButton("Cylinder"));
fourthRow.add(createRadioButton("Torus"));
return fourthRow;
}
private JPanel createMainPanel() {
JPanel mainPanel = new JPanel();
BoxLayout layout = new BoxLayout(mainPanel, BoxLayout.PAGE_AXIS);
mainPanel.setLayout(layout);
mainPanel.add(createFirstRow());
mainPanel.add(createSecondRow());
mainPanel.add(createThirdRow());
mainPanel.add(createFourthRow());
mainPanel.add(createFifthRow());
mainPanel.add(createSixthRow());
mainPanel.add(createSeventhRow());
mainPanel.add(createEighthRow());
return mainPanel;
}
private JRadioButton createRadioButton(String text) {
JRadioButton radioButton = new JRadioButton(text);
return radioButton;
}
private JPanel createSecondRow() {
JPanel secondRow = new JPanel();
secondRow.add(createRadioButton("Circle"));
secondRow.add(createRadioButton("Rectangle"));
secondRow.add(createRadioButton("Square"));
secondRow.add(createRadioButton("Triangle"));
return secondRow;
}
private JPanel createSeventhRow() {
JPanel seventhRow = new JPanel();
JButton button = new JButton("Enter");
seventhRow.add(button);
return seventhRow;
}
private JPanel createSixthRow() {
JPanel sixthRow = new JPanel();
JTextField textField = new JTextField(20);
sixthRow.add(textField);
return sixthRow;
}
private JPanel createThirdRow() {
JPanel thirdRow = new JPanel();
JLabel label = new JLabel("3D Shapes");
thirdRow.add(label);
return thirdRow;
}
private void showGui() {
frame = new JFrame("Shape Image Generator");
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.add(createMainPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Shapes23());
}
}
Here is a screen capture of how it looks. Note that I couldn't find the same icon as in your screen capture so I just used a different one.
I have a JPanel with layout set to null and the background is white. Then I added that JPanel to JScrollPane.
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class TestJScollPane extends JPanel {
private static final long serialVersionUID = 1L;
public TestJScollPane() {
initUI();
}
private void initUI()
{
JScrollPane scrollPane = new JScrollPane();
scrollPane.getViewport().setBackground(Color.GRAY);
scrollPane.setBounds(1, 1, 200, 200);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
setBorder(BorderFactory.createEtchedBorder(Color.GREEN, Color.MAGENTA));
setBackground(Color.WHITE);
setLayout(null);
JFrame frame = new JFrame();
scrollPane.setViewportView(this);
frame.add(scrollPane);
frame.setLayout(null);
frame.setVisible(true);
frame.setSize(800, 500);
frame.getContentPane().setBackground(Color.BLACK);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(30,30);
}
public static void main(String[] args)
{
new TestJScollPane();
}
}
My scenario is I have a zoom tool that if I zoom out the JPanel and all its shapes that were painted were scaled using AffineTransform. So I expect that if I zoom out, the background of JScrollPane was color gray but the actual was color white.
Apologies, I added a sample. Actually, this is not the actual code I created this so that I can provide a sample for you guys to help me.
I set the preferred size of JPanel to 30x30 so I expect that the background of JScrollPane will become visible but it was not.
Thanks in advance for any help.
By default the panel is sized to fit the viewport so you will not see the background of the viewport.
You need to implement the Scrollable interface of your JPanel to tell the scroll pane you want the panel displayed at its preferred size.
Or, instead of implementing the Scrollable interface yourself you can use the Scrollable Panel which, by default, will display the panel at its preferred size.
Changes to your code would be:
ScrollablePanel panel = new ScrollablePanel();
panel.setPreferredSize( new Dimension(30, 30) );
panel.setBorder(BorderFactory.createEtchedBorder(Color.GREEN, Color.MAGENTA));
panel.setBackground(Color.WHITE);
//panel.setLayout(null);
scrollPane.setViewportView(panel);
//scrollPane.setViewportView(this);
Change:
scrollPane.setViewportView(this);
To something like:
JPanel centerPanel = new JPanel(new GridBagLayout());
centerPanel.add(this);
scrollPane.setViewportView(centerPanel);
A GridBagLayout (by default, unless configured otherwise) will respect the preferred size of the child components and won't stretch them to fill the 'cell'. A scroll pane on the other hand, will stretch the content to (at least) fill the visible area.
Result:
But seriously, drop the use of null layouts. If the effect cannot be achieved using an existing layout (inbuilt or 3rd party) or a combination of layouts, it must have such esoteric positioning constraints that it deserves a custom layout manager.
My first panel's layout is BorderLayout and my second panel's layout is GridBagLayout. I don't know how to show them both at the same time.
I already tried adding two panels to on another panel.
Adding both to another panel is the way to go! But you have to make the right choice of LayoutManager for this "parent" panel. Let me give you an example:
The JFrame's content pane (where you add all your Components to) can be setup with a LayoutManager of your choice. See this runnable example, which creates two JPanels of 100x100 pixels in different colors. The panels are using the LayoutManagers you mentioned, but the main content pane of the JFrame is set to a BoxLayout (horizontal, but you can also set it to vertical!).
You can do this to any other panel, too. A panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS)); is enough. The below example just uses the content pane, but you can adapt it to your needs:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagLayout;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class TwoPanels extends JFrame {
private static final long serialVersionUID = 1L;
private static final Dimension DEFAULT_DIMENSION = new Dimension(100, 100);
public static void main(String[] args) {
new TwoPanels();
}
public TwoPanels() {
//create panel 1
JPanel panel1 = new JPanel(new BorderLayout());
panel1.setPreferredSize(DEFAULT_DIMENSION);
panel1.setBackground(Color.RED);
//create panel 2
JPanel panel2 = new JPanel(new GridBagLayout());
panel2.setPreferredSize(DEFAULT_DIMENSION);
panel2.setBackground(Color.GREEN);
//set content pane layout
setLayout(new BoxLayout(this.getContentPane(), BoxLayout.X_AXIS));
//add to content pane
add(panel1);
add(panel2);
//setup and display window
pack();
setVisible(true);
}
}
It looks like this:
EDIT: It's a little unclear from your question that you actually want to stack overlaying panels. You might find what you need here: https://docs.oracle.com/javase/tutorial/uiswing/components/layeredpane.html
Why cant I change the x and y coordinates of the icon? All I really need is to add the image to the screen. Do I even need to use a JLabel?
package bit;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class BIT extends JFrame
{
JLabel CL;
public BIT()
{
CL = new JLabel(new ImageIcon(this.getClass().getResource("final-image.jpg")));
CL.setBounds(0,0,100,100);
this.getContentPane().add(CL);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setBounds(5,5,1000,500);
this.setResizable(false);
this.setVisible(true);
}
public static void main(String[] args)
{
new BIT();
}
}
Unset the layout of the JFrame before adding controls with setBounds
this.setLayout(null);
You cannot set the x & y coordinates of the JLabel as the JFrame is using its default BorderLayout layout manager which arranges its components according to layout implementation.
setBounds only works when using absolute positioning (or null layout) and this option should be avoided(!).
It appears you are trying to position the JLabel in the top left-hand corner of the frame (0, 0). To do this you could:
Left-align the label
Add the label in the PAGE_START position
This would be:
CL = new JLabel(new ImageIcon(...), JLabel.LEFT);
this.getContentPane().add(CL, BorderLayout.PAGE_START);