Develop Reference

How do I create a new JFrame?

I'm a complete beginner to Java, and I'm finding some answers a bit too technical for me (even the most basic tutorials seem to give me syntax errors when I run the code). How, in really simple terms do I add a JButton to a JFrame? I've got as far as:
import javax.swing.JButton;
import javax.swing.JFrame;
public class JF {
public static void main(String[] args) {
JFrame myFrame = new JFrame();
/*some pretty basic code to initialize the JFrame i.e.
myFrame.setSize(300, 200);
This is as far as I got
*/
}
}
I would seriously appreciate some help!

Creating a new JFrame
The way to create a new instance of a JFrame is pretty simple.
All you have to do is:
JFrame myFrame = new JFrame("Frame Title");
But now the Window is hidden, to see the Window you must use the setVisible(boolean flag) method. Like this:
myFrame.setVisible(true);
Adding Components
There are many ways to add a Component to a JFrame.
The simplest way is:
myFrame.getContentPane().add(new JButton());//in this case we are adding a Button
This will just add a new Component that will fill the JFrame().
If you do not want the Component to fill the screen then you should either make the ContentPane of the JFrame a new custom Container
myFrame.getContentPane() = new JPanel();
OR add a custom Container to the ContentPane and add everything else there.
JPanel mainPanel = new JPanel();
myFrame.getContentPane().add(mainPanel);
If you do not want to write the myFrame.getContentPane() every time then you could just keep an instance of the ContentPane.
JPanel pane = myFrame.getContentPane();
Basic Properties
The most basic properties of the JFrame are:
Size
Location
CloseOperation
You can either set the Size by using:
myFrame.setSize(new Dimension(300, 200));//in pixels
Or packing the JFrame after adding all the components (Better practice).
myFrame.pack();
You can set the Location by using:
myFrame.setLocation(new Point(100, 100));// starting from top left corner
Finally you can set the CloseOperation (what happens when X is pressed) by
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
There are 4 different actions that you can choose from:
DO_NOTHING_ON_CLOSE //Nothing happens
HIDE_ON_CLOSE //setVisible(false)
DISPOSE_ON_CLOSE //Closes JFrame, Application still runs
EXIT_ON_CLOSE //Closes Application
Using Event Dispatch Thread
You should initialize all GUI in Event Dispatch Thread, you can do this by simply doing:
class GUI implements Runnable {
public static void main(String[] args) {
EventQueue.invokeLater(new GUI());
}
#Override
public void run() {
JFrame myFrame = new JFrame("Frame Title");
myFrame.setLocation(new Point(100, 100));
myFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new BorderLayout());
myFrame.getContentPane().add(mainPanel);
mainPanel.add(new JButton("Button Text"), BorderLayout.CENTER);
myFrame.pack();
myFrame.setLocationByPlatform(true);
myFrame.setVisible(true);
}
}

//I hope this will help
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JPanel;
public class JF extends JFrame
{
private JButton myButton;//Here you begin by declaring the button
public JF()//Here you create you constructor. Constructors are used for initializing variable
{
myButton = new JButton();//We initialize our variable
myButton.setText("My Button"); //And give it a name
JPanel panel1 = new JPanel();//In java panels are useful for holding content
panel1.add(myButton);//Here you put your button in the panel
add(panel1);//This make the panel visible together with its contents
setSize(300,400);//Set the size of your window
setVisible(true);//Make your window visible
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args)
{
JFrame frame = new JF();
frame.setTitle("My First Button");
frame.setLocation(400,200);
}
}

Putting everything into a JFrame

I want to know how to put put console output into a JFrame. For example, putting this output into a JFrame:
import static java.lang.System.out;
public class frame{
public static void main(String [] args){
out.println("hello");
}
}
How is it possible?

You need to set up the JFrame first.
JFrame frame = new JFrame("title");
Then, set the properties of the JFrame:
frame.setSize(1280,720); //Sets the program's size
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Tells the program to exit on close
frame.setResizable(true); //Tells the program if resizing is enabled
Then, create a panel to store the components:
JPanel p = new JPanel();
After that, you must add the panel to the JFrame like so:
frame.add(p);
Then, with that done, you can use the components supplied in the swing framework, and add them to the panel. A reference for these components can be found here: http://docs.oracle.com/javase/tutorial/uiswing/components/componentlist.html.
To create a component, use the following code:
JLabel label = new JLabel();
Then, use it's build in functions to change it:
label.setText("new text");
Then, once again, to add a component to a panel, use the panel's add() method:
panel.add(label);
Those are just the basics of making a GUI with java. A full tutorial can be viewed here:
http://docs.oracle.com/javase/tutorial/uiswing/
Good Luck!

I can help you with this, but let me please fix some syntax errors you have. When you put the import, an import can't be static (that I know of) and when you want to print out something using "System.out.print" or "System.out.println" you MUST include the "System" part of the line. If you want to add text to a a JFrame use the JLabel to import both just do this bit of code:
import javax.swing.*;
That should import all of your swing elements such as JLabel and JFrame and JPanel, and try this code it will make a window that will have a button and a label. The button doesn't do anything in this code:
import javax.swing.*;
public class main{
public static void main(String[] args)
{
/*
* Creates the frame, makes it visible, and makes
* appear in the center of the screen. While also making it have a close operation
*/
JFrame frame = new JFrame("Button");
frame.setVisible(true);
frame.setSize(300, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
//Creates the panel, and adds it to the frame
JPanel panel = new JPanel();
frame.add(panel);
//Creates the label and adds it to the panel, also sets the text
JLabel label = new JLabel();
label.setText("Welcome" + "\n" + "\n");
panel.add(label);
//Creates the button and adds it to the panel
JButton button1 = new JButton("Button 1");
panel.add(button1);
}
}

1.If you want to use JFrame you have to extend your class to a subclass of JFrame:
public class frame extends JFrame {}
2.a)If you want to put Text in your Frame use JLabel and add it to your frame:
JLabel hello = new JLabel("Hello");
add(hello);
2.b)If you want a console output just call System.out.println() in the constructor
Here is a small example class:
import javax.swing.JFrame;
import javax.swing.JLabel;
public class Frame extends JFrame {
public static void main(String args[]) {
new Frame();
}
Frame() {
System.out.println("Hello");
JLabel hello = new JLabel("Hello");
add(hello);
this.setSize(100, 100);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
}
}
have a look to the oracle lessons... or any java book!

If that is the case, I don't want to get into GUI just yet. (Learning from a book) Can I convert my current project to a jar file and have it automatically open a command prompt window upon double click?

Why is the window too small if I don't resize it?

I am wondering why when I enter this code without resizing the window, I cannot see anything:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GolfScoresGUI
{
public static void main(String[] args)
{
JFrame frame = new JFrame("GolfScoresGUI");
JLabel label = new JLabel("Did you score it? ");
JTextField textField = new JTextField(10);
frame.setVisible(true);
frame.getContentPane().add(textField);
}
}

add your components to a panel on which you call setPreferredSize, add the panel to the frame and call JFrame.pack().
JFrame.pack() updates the size of the frame to take the minimum possible size, given the size on its contained elements.
If you don't call it, the size will be something like 0x0, explaining why you don't see anything.
JFrame frame = new JFrame("GolfScoresGUI");
JPanel panel=new JPanel();
panel.setPreferredSize(new Dimension(600,400)); // Not mandatory. Without this, the frame will take the size of the JLabel + JTextField
frame.add(panel);
JLabel label = new JLabel("Did you score it? ");
JTextField textField = new JTextField(10);
panel.add(label);
panel.add(textField);
frame.setVisible(true);
frame.pack();
EDIT
btw, you should also add this line so that your application stops when you close the frame :
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

Everything is fine but you are not specifying any size for that JFrame. That is the problem. Try giving frame.setSize(width,height), or frame.pack(). By using one of this your problem will be solved.
http://docs.oracle.com/javase/tutorial/uiswing/components/frame.html
have a look at this to know about using JFrame in detailed.
Be carefull while using setVisible(true). Try to place setVisible(true) at the end of your GUI code, i.e: use it after adding all the GUI components to the container, because some times when you are adding more components it will not display some components until the frame is resized.

Placing a JLabel at a specific x,y coordinate on a JPanel

I'm trying to place a series of JLabels at specific X and Y coordinates on a JPanel (and set its height and width, too). No matter what I do, each label winds up immediately to the right of the previous label and has the exact same size as all of the others.
Right now, my Jpanel is in a Grid Layout. I've tried Absolute Layout (illegal argument exception results), Free Design (no labels appear), Flow Layout (everything just gets squeezed to the center), and a few others.
Not sure what I need to do to make this work. Can anyone help? Thanks!
JLabel lbl1 = new JLabel("label 1");
JLabel lbl2 = new JLabel("label 2");
JLabel lbl3 = new JLabel("label 3");
JLabel lbl4 = new JLabel("label 4");
JLabel lbl5 = new JLabel("label 5");
myPanel.add(lbl1);
myPanel.add(lbl2);
myPanel.add(lbl3);
myPanel.add(lbl4);
myPanel.add(lbl5);
lbl1.setLocation(27, 20);
lbl2.setLocation(123, 20);
lbl3.setLocation(273, 20);
lbl4.setLocation(363, 20);
lbl5.setLocation(453, 20);
lbl1.setSize(86, 14);
lbl2.setSize(140, 14);
lbl3.setSize(80, 14);
lbl4.setSize(80, 14);
lbl5.setSize(130, 14);

You have to set your container's Layout to null:
myPanel.setLayout(null);
However is a good advise also to take a look at the Matisse Layout Manager, I guess it is called GroupLayout now. The main problem with absolute positioning is what happens when the window changes its size.

Set the container's layout manager to null by calling setLayout(null).
Call the Component class's setbounds method for each of the container's children.
Call the Component class's repaint method.
Note:
Creating containers with absolutely positioned containers can cause problems if the window containing the container is resized.
Refer this link:
http://docs.oracle.com/javase/tutorial/uiswing/layout/none.html

Layout managers are used to automatically determine the layout of components in a container. If you want to put components at specific coordinate locations, then you should not use a layout manager at all.
myPanel = new JPanel(null);
or
myPanel.setLayout(null);

My advise is to use an IDE like NetBeans with its GUI editor. To inspect the code and because there are many ways:
Setting the layout manager, or for absolute positioning doing a myPanel.setLayout(null), has several influences.
In general, assuming you do your calls in the constructor of a JFrame, you can call pack() to start the layouting.
Then, every layout manager uses its own implementation of add(Component) or add(Component, Constraint). BorderLayout's usage is with add(label, BorderLayout.CENTER) and so on.

// Best solution!!
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Main {
public static void main(String args[]) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = (JPanel) frame.getContentPane();
panel.setLayout(null);
JLabel label = new JLabel("aaa");
panel.add(label);
Dimension size = label.getPreferredSize();
label.setBounds(100, 100, size.width, size.height);
frame.setSize(300, 200);
frame.setVisible(true);
}
}

You can use your own method that calling by setSize, setLocation values for directly....! `
As well i show you how to use JProgress Bar
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class installComp{
void install(Component comp, int w, int h, int x, int y){
comp.setSize(w,h);
comp.setLocation(x,y);
}
}
class MyFrame extends JFrame{
int cur_val = 0;
JButton btn = new JButton("Mouse Over");
JProgressBar progress = new JProgressBar(0,100);
MyFrame (){
installComp comp=new installComp();
comp.install(btn,150,30,175,20);
comp.install(progress,400,20,50,70);
btn.addMouseListener(new MouseAdapter(){
public void mouseEntered(MouseEvent evt){
cur_val+=2;
progress.setValue(cur_val);
progress.setStringPainted(true);
progress.setString(null);
}
});
add(btn);
add(progress);
setLayout(null);
setSize(500,150);
setResizable(false);
setDefaultCloseOperation(3);
setLocationRelativeTo(null);
setVisible(true);
}
}
class Demo{
public static void main(String args[]){
MyFrame f1=new MyFrame();
}
}

How to place images on top of each other in java

I have a background image of a road, which I have displayed on a JFrame using an ImageIcon. I want to put a car on top of that background image at a certain (x,y) location.
I tried using another ImageIcon and the background does not appear when I run the program , however the car does.
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class Gui extends JFrame {
private ImageIcon northcar = new ImageIcon("src/north.gif");
private ImageIcon usIcon = new ImageIcon("src/trafficLight.jpg");
public Gui() {
add(new JLabel(usIcon)); // background image does not appear after the i added the northcar label
add(new JLabel(northcar)); // this picture can be seen
}
public static void main(String[] args) {
Gui frame = new Gui();
frame.setTitle("TestImageIcon");
frame.setLocationRelativeTo(null); // Center the frame
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(0, 0, 650, 650);
frame.setVisible(true);
}
}
I heard about using a canvas but have no clue. Any ideas ?
Many Thanks

How about using LayeredPane, this might help.

add(new JLabel(usIcon));
add(new JLabel(northcar));
Change the order to:
add(new JLabel(northcar));
add(new JLabel(usIcon));
Read up on Z-Order. Simply the last component added gets painted first.