awt

I keep getting a Run Time error that says I am having an Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException it is saying a [line 65] but to me it just looks like a basic if statement. I can give some background. this frame is call from a sequence of frames that is then once the state is selected sent to a new frame that contains states A-C cities. This current frame will work only when Alabama is not the state selected. (I have not created the other frames for the other states hence why they are commented out) I can put up the code to the other frame it is supposed to call

import java.awt.*; import java.awt.event.*; public class QuadraticSolver extends Frame implements ActionListener, WindowListener { private TextField tfX2; private TextField tfX; private TextField tfNum; private TextField tfVal1; private TextField tfVal2; private TextField tfRoots; private Label lblX2; private Label lblX; private Label lblNum; private Label lblVal1; private Label lblVal2; private Label lblRoots; private Button btnCheckRoots; private Button btnCalc; private Button btnClear; double a = 0, b = 0, c = 0; double Val1 = 0, Val2 = 0, Discriminant = 0; String StrVal1, StrVal2; public

In java awt or swing when you want to change painting of some component you usually have to override the method paint(Graphics g) (in awt) or paintComponent(Graphics g) (in swing). This is usually (maybe allways - I'm not sure) done when you are creating the component for example: JPanel jPanel = new JPanel() { @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g; //... my implementation of paint, some transfromations, rotation, etc } }; Imagine that you have container of components which could for example consists of some JLabels, some

I have found an open source application that creates a JFrame to display some content. I would like to "embed" this JFrame into an applet, so everything that is displayed in the Jframe will be displayed in the applet - is this possible? Thanks for your help! Create an instance of the frame. Get the content pane of the frame. Add the content pane to the applet. Andrew Thompson ..open source application that creates a JFrame.. Since the source is available, take whatever they do in the frame, and do that instead in an applet (with some slight variants & gotchas). Some typical problems with using

I'm using bezier curves in my libgdx project. I was testing the desktop version using java.awt.geom with GeneralPath but when I went to test on android, it raised an error saying that I can't import java.awt . Android have corresponding classes for GeneralPath , Point2D etc so my question is how can I use those classes in their respective environments? Android does not have an AWT implementation, so references to those classes won't work on Android. (On the desktop you're getting those classes from the JDK.) Technically, you can put code that depends on AWT in your desktop Libgdx backend, and

I want to add a JComboBox in Swing that is simple but I want to assign the values for each items in combo. I have the following code JComboBox jc1= new JComboBox(); jc1.addItem("a"); jc1.addItem("b"); jc1.addItem("c"); Now what I want is that when click on combo box it should return 1, 2 and 3 correspondingly instead of a ,b, c. Is there any way to assign the key values for each items in combo box? You can add an item as an object instead of adding String like this: JComboBox<ItemClass> jc = new JComboBox<ItemClass>(); jc.addItem(item1); jc.addItem(item2); jc.addItem(item3); So to return key,

I have two JPanels on a JLayeredpane. One of them displays a pdf and the overlapping one has a transparent background (I have used setOpaque(false)). Now I can add drawings to the transparent panel such that it seems I'm actually annotating the pdf. I want to have a eraser tool to erase these annotations. I tried using the following code @Override public void draw(Graphics2D g2) { g2.setPaint(Color.WHITE); g2.setComposite(AlphaComposite.getInstance(AlphaComposite.CLEAR)); g2.setBackground(new Color(255, 255, 255, 0)); g2.setStroke(new BasicStroke(thickness, BasicStroke.CAP_ROUND, BasicStroke

I'm trying to draw simple shapes with Canvas, in this class I've set the painting public class Game extends Canvas{ //FIELDS public int WIDTH = 1024; public int HEIGHT = WIDTH / 16 * 9; //METHODS public void start(){ Dimension size = new Dimension (WIDTH, HEIGHT); setPreferredSize(size); paint(null); } public void paint(Graphics g){ g.setColor(Color.GREEN); g.fillRect(0, 0, WIDTH, HEIGHT); g.setColor(Color.BLACK); g.fillOval(100, 100, 30, 30); } } And in this the Window public class MainW { public static void main(String[] args) { Game ga = new Game(); JFrame frame = new JFrame (); frame