I'm new to Java programming and am having difficulty with the drawString method delaying almost a full second before drawing after the JFrame appears. Here is the test class I ran to verify it was drawString causing the delay(I'm sorry it is written out, I'm posting on my phone):
import javax.swing.*;
import java.awt.*;
public class Frame1 extends JFrame{
JPanel jp;
Container c;
Frame1(){
setSize(new Dimension(300,300));
c = getContentPane();
c.add(jp = new JPanel(){
public void paint(Graphics g){
g.drawString("hello", 20, 20);
}
});
setVisible(true);
}
public static void main(String args[]){
new Frame1();
}
}
Is there a way to use drawString without this delay? I'm using a MacBook Pro with Mac OSX 10.6.3. Thanks for your help.
Related
I am trying to create a simple program using JInternalFrame on Swing and when i run my code, it suddenly produces a blue background. Can anyone tell me how i can remove it?
here is the code i tried
import javax.swing.*;
public class Main extends JFrame {
JDesktopPane dp = new JDesktopPane();
JInternalFrame intf = new JInternalFrame("demo");
public void initialize() {
setTitle("Test Program");
setSize(500, 500);
setLocationRelativeTo(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
public Main() {
intf.setSize(150, 200);
intf.setVisible(true);
dp.add(intf);
add(dp);
initialize();
}
public static void main(String args[]) {
new Main();
}
}
It's part of the PL&F.
To literally remove it you can make the JDesktopPane non-opaque:
dp.setOpaque(false);
Or set the background to a colour that you like:
dp.setBackground(new java.awt.Color(200,200,200));
But it looks weird with a light colour.
There's probably someway of configuring the macOS PL&F. All just live with macOS looking like macOS wants to look.
I'm new here. Been reading questions and answers for aeons. Recently I found time to start studying Java, and I'm seriously enjoying the process. Until I started to write some code. The getting stuck is killing me. So I've come to seek advice on something extremely simple but I cannot crack it.
The code below attempts to create a frame, maximize it, and place elements inside. I was just fooling around. First the button1, I tried to change its size (so I got it into a FlowLayout). Then a button in the mainPanel, just to... try. Then an oval. I tried for 2 hours to get the oval to display but it is Impossible. When I found about "drawOval" I thought that was it but it made no difference. And to think that I was planning for the button1 to create Moving Balls. I'm so, So far away from that.
Please, why does the silly Oval refuse to display itself. Help.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class MainClass {
JFrame frame = new JFrame();
JPanel mainPanel = new JPanel();
JPanel southPanel = new JPanel();
JButton button1 = new JButton("Button1");
JButton button2 = new JButton("Button2");
Oval oval = new Oval();
public static void main(String[] args) {
MainClass program = new MainClass();
program.go();
}
public void go() {
buildGUI();
}
public void buildGUI() {
button1.setBorder(BorderFactory.createMatteBorder(2,2,2,2, Color.BLACK));
button1.addActionListener(new Button1Listener());
frame.getContentPane().add(BorderLayout.CENTER, mainPanel);
button1.setPreferredSize(new Dimension(200, 50));
frame.getContentPane().add(BorderLayout.SOUTH, southPanel);
southPanel.add(button1);
mainPanel.add(button2);
mainPanel.add(oval);
frame.setSize(400, 400);
frame.setExtendedState(frame.getExtendedState() | JFrame.MAXIMIZED_BOTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
class Button1Listener implements ActionListener {
#Override
public void actionPerformed(ActionEvent event) {
//What the button will do.
}
}
}
And the Oval part
import java.awt.*;
import javax.swing.*;
public class Oval extends JPanel {
public void paintComponent(Graphics g) {
g.setColor(Color.orange);
g.fillOval(20, 50, 100, 100);
}
}
JPanel uses a FlowLayout by default. Since you Oval class doesn't provide any sizing hints, then it's set to a default size of 0x0.
Start by updating your class to something more like...
public class Oval extends JPanel {
#Override
public Dimension getPreferredSize() {
return new Dimension(120, 150);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.orange);
g.fillOval(20, 50, 100, 100);
}
}
to create Moving Balls.
Ok, you might want to have a look at:
java bounceBall mouse escape
paintComponent not working
package Main;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
public class Main extends JFrame{
public static void main(String[] args) {
int width = 800;
int height = 600;
String title = "Test";
JFrame display = new JFrame();
display.setTitle(title);
display.setSize(width, height);
display.setVisible(true);
display.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void paint(Graphics g) {
g.setColor(Color.white);
g.drawLine(0, 100, 800, 300);
getContentPane().setBackground(Color.black);
}
}
I'm using Java's JFrame. So this isn't recognising the paint method and cant figure out why. I've been looking on YouTube videos and having a look to see if anyone has had similar problems, however everything I've found doesn't seem to help the problem.
when i set the background colour in the main part, it works, bit in paint, it doesn't seem to do anything and leaves it blank.
Its a white line over a black background, so i should easily be able to see it.
Admittedly, I don't know much about Swing (I prefer JavaFX). However, it's clear that your Main class is a JFrame, so you should not make a new one within it. All of those methods you call on display are built in your current class. Basically, within your JFrame you made a new JFrame. However, your paint method was being called on the parent JFrame, which you never made visible. This solves your problem (you may have to fullscreen the window):
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
public class Main extends JFrame{
public static void main(String[] args) {
new Main();
}
public Main() {
int width = 800;
int height = 600;
String title = "Test";
setTitle(title);
setSize(width, height);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void paint(Graphics g) {
super.paint(g);
g.setColor(Color.WHITE);
g.drawLine(100, 100, 800, 300);
getContentPane().setBackground(Color.black);
}
}
You are creating an instance of JFrame with
JFrame display = new JFrame();
But the JFrame class has no logic to draw a white line on a black background. That logic is in your custom class Main. So instead, you should create an instance of Main:
JFrame display = new Main();
However, that change along still won't fix the problem because you are setting the background color of the "content pane" but trying to draw directly on the JFrame itself. The preferred solution here is to extend JPanel instead of JFrame and override its paintComponent() method. Then create an instance of your new class to use as the content pain:
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainPanel extends JPanel{
public static void main(String[] args) {
int width = 800;
int height = 600;
String title = "Test";
JFrame display = new JFrame();
display.setTitle(title);
display.setSize(width, height);
display.setVisible(true);
display.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
display.setContentPane(new MainPanel());
}
public MainPanel() {
setBackground(Color.black);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.white);
g.drawLine(0, 100, 800, 300);
}
}
Notes:
I call setBackground() in the constructor because it does not rely on the Graphics instance passed to paintComponent(). This also avoids the overhead of another function call for each render.
In paintComponent(), I call super.panitComponent(). This allows JPanel to clear the area to be painted and any other necessary initialization.
This question already has answers here:
Swing - paintComponent method not being called
(2 answers)
Closed 5 years ago.
I am trying to draw a simple rectangle but I think the paintComponent method is not getting called.
Here is the code for the class with main method:
package painting;
import java.awt.*;
import javax.swing.*;
public class Painting {
public static void main(String[] args) {
JFrame jf;
jf = new JFrame("JUST DRAW A RECTANGLE");
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.setLayout(null);
jf.setLocationRelativeTo(null);
jf.setSize(600,600);
jf.setVisible(true);
Mainting maint = new Mainting();
jf.add(maint);
}
}
and the class with paintComponent()
package painting;
import java.awt.*;
import javax.swing.*;
public class Mainting extends JPanel {
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawRect(0, 0 , 200, 200);
System.out.println("haha");
g.setColor(Color.red);
}
}
What is the problem here, I cannot figure out...
While the answers already provided might have resulted in the rectangle appearing, the approach was less than optimal. This example aims to show a better approach. Read the comments in the code for details.
Note that Swing/AWT GUIs should be started on the EDT. This is left as an exercise for the reader.
import java.awt.*;
import javax.swing.*;
public class Painting {
public static void main(String[] args) {
JFrame jf = new JFrame("JUST DRAW A RECTANGLE");
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// null layouts cause more problems than they solve. DO NOT USE!
//jf.setLayout(null);
jf.setLocationRelativeTo(null);
/* if components return a sensible preferred size,
it's better to add them, then pack */
//jf.setSize(600, 600);
//jf.setVisible(true); // as mentioned, this should be last
Mainting maint = new Mainting();
jf.add(maint);
jf.pack(); // makes the GUI the size it NEEDS to be
jf.setVisible(true);
}
}
class Mainting extends JPanel {
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.RED);
g.drawRect(10, 10, 200, 200);
System.out.println("paintComponent called");
/* This does nothing useful, since nothing is painted
before the Graphics instance goes out of scope! */
//g.setColor(Color.red);
}
#Override
public Dimension getPreferredSize() {
// Provide hints to the layout manager!
return new Dimension(220, 220);
}
}
Try setting your layout manager to eg. BorderLayout
so use
jf.setLayout(new BorderLayout());
and then add your component with some constraints
Mainting maint = new Mainting();
jf.add(maint,BorderLayout.CENTER);
I have drawn a rectangle using a JPanel
My main objective is to store my Requirement Engineering chapter into a JPanel or a JFrame
import java.awt.*;
import javax.swing.*;
class RequirementEngineering extends JPanel
{
public void paintComponent(Graphics g)
{
super.paintComponent();
g.drawRect(10,10,60,60);
g2.drawString("Feasibility study", 20, 20); //rectangle is my main objective, I will look after the string later
}
public static void main(String[] args)
{
}
}
how do I display the JPanel? I know, JApplet doesn't require a main method, but how do we represent JPanel in main() method?
I have this doubt for long, and other posts are confusing me further, Could I have a direct question
My main question being "How to add JFrame to JPanel" pertaining my current coding
thanks in advance
see if you need to use a Window based app, you can do as:
JPanel customPanel = new RequirementEngineering();
JFrame frame = new JFrame("my window");
frame.getContentPane().add(customPanel );
frame.setSize(300,200);
frame.setVisible(true);
If you need in Applet,
public class JAppletExample extends JApplet {
public void init() {
Container content = getContentPane();
JPanel customPanel = new RequirementEngineering();
content.add(customPanel );
}
And you can run it using appletViewer or in any Web Browser such as IE.