Adding JPanel to JFrame? - java

I'm trying to add a JLabel to a JPanel to a JFrame. I set the border for the JPanel, but all I see on the JFrame is a small black square in the center of my frame. Whatever I do I can't change the size or location of it. Please help.
Start main = new Start();
Random random = new Random();
JFrame mainFrame = new JFrame("MainFrame");
JPanel mainPanel = new JPanel();
JLabel welcomeLabel = new JLabel();
mainFrame.add(main);
mainFrame.setLayout(new GridBagLayout());
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setTitle(names[random.nextInt(names.length)]);
mainFrame.pack();
mainFrame.setVisible(true);
mainFrame.setSize(mainFrameX, mainFrameY);
mainFrame.setResizable(false);
mainFrame.setLocationRelativeTo(null);
mainFrame.add(mainPanel);
mainPanel.add(welcomeLabel);
mainPanel.setBorder(new LineBorder(Color.BLACK));
mainPanel.setSize(new Dimension(200, 200));
welcomeLabel.setFont(new Font("Verdana", 1, 20));
welcomeLabel.setLocation(100, 100);
main.start();

Suggestions:
You will want to read the tutorial, Laying out Components, as it will explain how to code with the Swing layout managers, and this information is essential to solve your current problem.
One caveat: I urge you to avoid the temptation to use the null layout as use of it will lead to creation of code that is very hard to maintain or upgrade.
Your JLabel, welcomeLabel, will of course need some text to be visible.
Don't set it's location via setLocation(...) but again use the layout managers to do the dirty work of placing and sizing your components.
You will also want to call pack() and setVisible(true) on your JFrame after adding all initial components.

Hovercraft is right (+1), make sure you understand how the layout managers are working.
The order in which you do things are important, especially when dealing with the top level containers...
Start main = new Start();
Random random = new Random();
JFrame mainFrame = new JFrame("MainFrame");
JPanel mainPanel = new JPanel();
JLabel welcomeLabel = new JLabel();
welcomeLabel.setFont(new Font("Verdana", 1, 20));
mainPanel.add(welcomeLabel);
mainPanel.setBorder(new LineBorder(Color.BLACK));
// Do this first
mainFrame.setLayout(new GridBagLayout());
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setTitle(names[random.nextInt(names.length)]);
// Add your components
mainFrame.add(main);
mainFrame.add(mainPanel);
// Prepare the window for showing, now you have some content.
mainFrame.setResizable(false);
mainFrame.pack();
mainFrame.setVisible(true);
mainFrame.setLocationRelativeTo(null);
main.start();
This will still only produce a small black square in the window, because the JLabel has no content and therefore it's preferred size is going to be (something like) 2x2 (because of the border).
Try adding some text to...
welcomeLabel.setText("Welcome");
And then see the difference

Related

Java: What Layout Manager would be best for a game menu?

===================
Game Name
Play
Exit
===================
the above is what my previous game menu looked like. I used the Box Layout to create it but it was very tedious. Is there there a better layout manager that I could use?
here is the code for those that asked of the main pane.
private JButton JB;
private JButton EB;
private JOptionPane JO;
public StartUpWindow(){
super("Pong");
JPanel outside = new JPanel();
JPanel inside = new JPanel();
setLayout(new BorderLayout());
outside.setLayout(new BoxLayout(outside, BoxLayout.LINE_AXIS));
inside.setLayout(new BoxLayout(inside, BoxLayout.PAGE_AXIS));
outside.add(Box.createHorizontalStrut(280));
outside.add(inside);
outside.add(Box.createHorizontalStrut(20));
inside.add(Box.createVerticalStrut(20));
JLabel title = new JLabel(" "+"Pong");
title.setFont( new Font("Serif", Font.BOLD, 40));
inside.add(title);
inside.add(Box.createVerticalStrut(20));
JButton btt1 = new JButton("Start");
Dimension d = new Dimension(200,40);
btt1.setSize(d);
btt1.setMinimumSize(d);
btt1.setMaximumSize(d);
btt1.setPreferredSize(d);
JButton btt2 = new JButton("Credits");
btt2.setSize(d);
btt2.setMinimumSize(d);
btt2.setMaximumSize(d);
btt2.setPreferredSize(d);
JButton btt3 = new JButton("Exit");
btt3.setSize(d);
btt3.setMinimumSize(d);
btt3.setMaximumSize(d);
btt3.setPreferredSize(d);
inside.add(btt1);
btt1.addActionListener(this);
btt1.setActionCommand("start");
inside.add(Box.createVerticalStrut(5));
inside.add(btt2);
btt2.addActionListener(this);
btt2.setActionCommand("credits");
inside.add(Box.createVerticalStrut(5));
inside.add(btt3);
btt3.addActionListener(this);
btt3.setActionCommand("exit");
inside.add(Box.createVerticalStrut(20));
add(outside);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(800,600);
this.setVisible(true);
this.setResizable(false);
this.setLocation(450,200);
inside.setBackground(Color.GRAY);
outside.setBackground(Color.GRAY);
}
I agree that BoxLayout is tedious but I admire its relative simplicity.
Another quick and easy option is to use the "javax.swing.Box" class instead of using a layout manager directly.
Box box = Box.createVerticalBox();
box.add(new JLabel("Game"));
box.add(Box.createVerticalStrut(20));
box.add(new JLabel("Button 1"));
box.add(new JLabel("Button 2"));
JFrame frame = new JFrame();
frame.add(box);
frame.pack();
frame.setVisible(true);
Box offers a number of useful methods. You can use it to create vertical and horizontal boxes, create "struts" to reserve horizontal and vertical space, and create "glue" to fill in available space when the layout grows.
Of course you could also use GridBagLayout, but I tend to reserve it for more complex layouts. Box and his cousin BoxLayout are often good enough for simple layouts and are easy for new programmers who are maintaining the application to understand and debug.
Why not simply use no layout and instead draw everything using a Graphics object?
You could easily achieve this by creating a BufferStrategy bound to the Window object (invoke createBufferStrategy on the latter) then call a few simple methods to easily redraw the screen.
This also means it's simpler to then code the game's display when you're playing it.
BufferStrategy also allows the use of page flipping and other forms of buffering when the application is in fullscreen exclusive mode, allowing it to refresh the screen very rapidly in many applications.

How to re-size JButton

I've bee teaching myself java and following along with the problems in the book. I'm trying to make a display for my calculator. In the example(I did not attach this) the buttons were a smaller size than what mine are and I can't figure out how to reformat them. I tried using the dimension class but it had no affect. Also, I can't get my text at the top of the calculator to align left.
Here is my code:
public class Calculator extends JFrame {
public Calculator() {
setTitle("Calculator");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setSize(300, 300);
setLayout(new BorderLayout());
JPanel numberPanel = new JPanel();
add(numberPanel, BorderLayout.CENTER);
numberPanel.setLayout(new GridLayout(4, 3, 3, 3));
for(int i = 1; i < 10; i++) {
JButton button = new JButton(String.valueOf(i));
numberPanel.add(button);
}
JButton zero = new JButton("" + 0);
JButton dot = new JButton(".");
JButton clear = new JButton("C");
numberPanel.add(zero);
numberPanel.add(dot);
numberPanel.add(clear);
JPanel keyPanel = new JPanel();
add(keyPanel, BorderLayout.EAST);
keyPanel.setLayout(new GridLayout(4, 1, 3, 3));
JButton plus = new JButton("+");
JButton minus = new JButton("-");
JButton times = new JButton("*");
JButton divide = new JButton("/");
keyPanel.add(plus);
keyPanel.add(minus);
keyPanel.add(times);
keyPanel.add(divide);
JPanel equalsPanel = new JPanel();
add(equalsPanel, BorderLayout.SOUTH);
equalsPanel.setLayout(new GridLayout(1, 1));
JButton equals = new JButton("=");
equalsPanel.add(equals);
JPanel textPanel = new JPanel();
add(textPanel, BorderLayout.NORTH);
JTextField inputBox = new JTextField("0.0");
inputBox.setHorizontalAlignment(JTextField.LEFT);
inputBox.setEditable(false);
Font font = new Font("MonoSpaced", Font.BOLD, 20);
inputBox.setFont(font);
textPanel.add(inputBox);
setVisible(true);
}
public static void main(String[] args) {
new Calculator();
}
}
Imports were left off for brevity
GridLayout will laugh at you when you try and set a dimension. It does respect preferred sizes. You should select a layout manager that will respect preferred sizes. Or you can simply pack() (after you add all your components) your frame instead of setSize() and all the components preferred sizes will kick in. (Disclaimer - because of GridLayout though, if you try and resize the frame after that, you components will resize again)
See more at How to use Layout Managers. For a quick view of which layout managers respect preferred sizes and which ones don't, have a look at this post.
A common approach is to nest panels with different layout managers also, as seen here
UPDATE
As mentioned preciously, you should just call pack on the frame instead of set size. With your current code, this would cause the frame to be very small because of the preferred sizes of the components. If you want the buttons to have a bigger preferred size, you can set the font to a bigger font and/or use button.setMargins(new Insets(w,x,y,x)); to make the margins bigger. But it is preferred to pack the frame.
I would recommend using the Window Builder add-on if you’re using Eclipse. This tool will help you with many aspects of Swing. Learn by doing.
WindowBuilder Dowload Link

JPanel create empty space between subPanels

I'm developing a Java application for homework. This is my code
JLabel queryHandlerL = new JLabel("Create php to handle query results", JLabel.CENTER);
final JCheckBox queryHandlerCB = new JCheckBox();
JPanel checkBoxPanel = new JPanel(new FlowLayout());
checkBoxPanel.add(queryHandlerL);
checkBoxPanel.add(queryHandlerCB);
// Query Panel
// set image
picLabelQuery = new JLabel("",JLabel.LEFT);
picLabelQuery.setIcon(currentPicForm);
JPanel queryPanel = new JPanel();
final JButton queryButton = new JButton("Insert a query");
queryPanel.add(queryButton);
queryPanel.add(picLabelQuery);
// Panel create
final JButton createButton = new JButton("Create");
JPanel createPanel = new JPanel(new FlowLayout(FlowLayout.TRAILING));
createPanel.add(createButton);
JPanel finalPanel = new JPanel(new GridLayout(0, 1,5,2));
finalPanel.add(queryPanel);
finalPanel.add(checkBoxPanel);
finalPanel.add(createPanel);
finalPanel.setBorder(BorderFactory.createTitledBorder("SQL connection"));
setLayout(new GridBagLayout());
add(finalPanel);
I have a CardLayout and this is a Window inside this CardLayout. The last add(finalPanel) refers to the panel of the CardLayout.
This piece of code works but this is the result
How do I remove the space that is automatically created between the panels?
How do I remove the space that is automatically created between the panels?
Use a different layout manager for the panel. The GridLayout will always resize components to take up all the space in the panel.
Maybe you can use a BoxLayout or a GridBagLayout. You can also nest panels with different layout managers to get your desired effect.
Read the section from the Swing tutorial on Layout Managers for more information and examples.
You should pack() your surrounding panel or set the height to a desired value.

createVerticalGlue() in BoxLayout not functioning

I have used the createVerticalGlue() successfully on a number of times. However in the following screen building code it is not working. I am still wondering why.
The situation is that I have two JPanels (leftPanel, rightPanel) within another Panel (centralPanel). Each of these two panels will host two JComponents using a BoxLayout Y-Axis. I want to distribute the remaining free space before, between and after the two JComponents.
I know that I can use empty borders and rigid areas to solve the problem but it happens that I am a bit hard headed!
My appologies for the long question.
public class MemberGUI extends JFrame {
JPanel contPane = (JPanel) this.getContentPane();
JPanel centralPanel = new JPanel();
JPanel leftPanel = new JPanel();
JPanel rightPanel = new JPanel();
JPanel lowerPanel = new JPanel();
JLabel title = new JLabel("Add/Delete Member");
JLabel nameLbl = new JLabel("Member's name");
JLabel idLbl = new JLabel ("Member ID");
JTextField nameFld = new JTextField(10);
JTextField idFld = new JTextField(10);
public void buildMe(){
//LayoutManagers
contPane.add(title,BorderLayout.PAGE_START);
contPane.add(centralPanel,BorderLayout.CENTER);
contPane.add(lowerPanel,BorderLayout.PAGE_END);
centralPanel.add(leftPanel);
centralPanel.add(rightPanel);
leftPanel.setLayout(new BoxLayout(leftPanel,BoxLayout.Y_AXIS));
rightPanel.setLayout(new BoxLayout(rightPanel,BoxLayout.Y_AXIS));
//leftPanel.add(Box.createRigidArea(new Dimension(0,50)));
leftPanel.add(Box.createVerticalGlue());
leftPanel.add(idLbl);
leftPanel.add(Box.createVerticalGlue());
leftPanel.add(nameLbl);
leftPanel.add(Box.createVerticalGlue());
//rightPanel.add(Box.createRigidArea(new Dimension(0,50)));
rightPanel.add(Box.createVerticalGlue());
rightPanel.add(idFld);
rightPanel.add(Box.createVerticalGlue());
rightPanel.add(nameFld);
rightPanel.add(Box.createVerticalGlue());
// JFrame Settings
this.setSize(500,400);
this.setResizable(false);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
this.setVisible(true);
}
}
afaics, centralPanel has default layoutManager, which is FlowLayout. This always sizes its children to their prefSize, so the glue never comes into play.
Nesting containers comes at a price (which nesting wizards like #Andrew happily pay :-) Also, it's not entirely trivial to get right (f.i. replace the upper textField with a comboBox to see the mis-alignment). In the longer run, there's hardly a route around learning to master a more powerful manager, like f.i. MigLayout (my current personal favorite)

Java Positioning a list on a GUI

I'm trying to add a JList to a GUI, but am wondering how to position it? I want it to appear on the right hand side of the TextArea for data that will be sent to the GUI for selection.
Can anyone suggest how to do this? Here is the code (note: very new to Java and GUI's)
protected static void createAndShowGUI() {
GUI predict = new GUI();
JFrame frame = new JFrame("Phone V1.0");
frame.setContentPane(predict.createContentPane());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setMinimumSize(new Dimension(300, 400));
frame.setVisible(true); // Otherwise invisible window
}
private JPanel createContentPane() {
JPanel pane = new JPanel();
TextArea = new JTextArea(5, 10);
TextArea.setEditable(false);
TextArea.setLineWrap(true);
TextArea.setWrapStyleWord(true);
TextArea.setWrapStyleWord(true);
pane.setLayout(new BoxLayout(pane, BoxLayout.Y_AXIS));
//Adds the buttons from Top to Bottom
String[] items = {"dsfsdfd"};
list = new JList(items);
JScrollPane scrollingList = new JScrollPane(list);
int orient = list.getLayoutOrientation();
JPanel window = new JPanel();
pane.add(window);
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(5, 3));
JButton[] buttons = new JButton[] {
new JButton("Yes"),
new JButton(""),
new JButton("Clr"),
new JButton("1"),
new JButton("2abc"),
new JButton("3def"),
new JButton("4ghi"),
new JButton("5jkl"),
new JButton("6mno"),
new JButton("7pqrs"),
new JButton("8tuv"),
new JButton("9wxyz"),
new JButton("*+"),
new JButton("0_"),
new JButton("^#")
}; // Array Initialiser
for (int i = 0; i < buttons.length; i++) {
buttonPanel.add(buttons[i]);
buttons[i].addActionListener(this);
}
pane.add(TextArea);
pane.add(list);
pane.add(buttonPanel);
return pane;
}
Read the section from the Swing tutorial on Using Layout Mananger. There is no need to only use a single layout manager. You can nest layout managers to get the desired effect.
Wrap your TextArea and list in a new panel with a BorderLayout manager. Basically the BorderLayout manager lets you arrange components using north, south, east, west and center coordinates. The components at the center takes all available space as the parent container has more space available to it.
private JPanel createContentPane() {
JPanel pane = new JPanel(); //this is your main panel
JPanel textAreaPanel = new JPanel(new BorderLayout()); //the wrapper
//Some more code...
//Then at the end
//Make your TextArea take the center
textAreaPanel.add(TextArea, BorderLayout.CENTER);
//And the list to the east
textAreaPanel.add(list, BorderLayout.EAST);
pane.add(textAreaPanel);
pane.add(buttonPanel);
return pane;
}
The cool thing is that you can nest panels inside other panels, adding them different layout managers to get your desired layout.
On an unrelated note, try to follow Java naming conventions. Instead of JTextArea TextArea use JTextArea textArea. It makes it easier for you and people reading your code to understand it.
You could use a layout manager like Mig Layout for that kind of positionning.
(source: miglayout.com)
I could recommend you FormLayout. Before I found this layout I had a real pain with GridBagLayout. FormLayout is more powerful and much more convenient to learn and use and it is free. Give it a chance.
As others suggested, familiarize yourself with the concept of layout managers. There are several that come with the standard Swing API and several good 3rd party ones out there.
In addition, you will want to add the JList to a scroll pane (JScrollPane). You may want to consider adding it to a split pane (JSplitPane). And by consider I don't mean "do it because some guy on the net said so" I mean "do it if it makes sense for your end users".

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