Aligning Diagram in Java

0 votes

I try to draw a rectangular in Java. I set the frame size (800,400) and resizable(false) rectangular's x = 50, y = 50 width = 700 height = 300. Why isn't it in the middle? 

Thank you.

Feb 11, 2019 in Java by Sushmita
• 6,910 points
372 views

1 answer to this question.

0 votes

Without any evidence otherwise, I'd guess you've over-ridden the paint method of something like a JFrame and are painting directly to it.

The problem is, frames have decoration (a border and title bar for example), which takes up space inside the frame...

enter image description here

Technically, this is correct. The rectangle is painted in the center of frame, but because of the frame's decorations, it looks like it's slightly high...

Instead, you should be painting onto the frame's content area instead.

enter image description here

Here the rectangle now looks correctly centered. In my tests, I set the first frame (bad) to 800x400, I made the second frame's content pane's preferred size 800x400, which made the frame size actually 816x438, as the frame's decorations are now outside of the paint area.

public class CenterOfFrame {

    public static void main(String[] args) {
        new CenterOfFrame();
    }

    public CenterOfFrame() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                new BadFrame().setVisible(true);

                JFrame goodFrame = new JFrame();
                goodFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                goodFrame.setContentPane(new PaintablePane());
                goodFrame.pack();
                goodFrame.setLocationRelativeTo(null);
                goodFrame.setVisible(true);

            }
        });
    }

    public class BadFrame extends JFrame {

        public BadFrame() {
            setSize(800, 400);
            setDefaultCloseOperation(EXIT_ON_CLOSE);
        }

        @Override
        public void paint(Graphics g) {
            super.paint(g);
            paintTest(g, getWidth() - 1, getHeight() - 1);
        }
    }

    public void paintTest(Graphics g, int width, int height) {
        g.setColor(Color.RED);
        g.drawLine(0, 0, width, height);
        g.drawLine(width, 0, 0, height);
        g.drawRect(50, 50, width - 100, height - 100);
    }

    public class PaintablePane extends JPanel {

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(800, 400);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g); //To change body of generated methods, choose Tools | Templates.
            paintTest(g, getWidth() - 1, getHeight() - 1);
        }
    }
}

This is, one of many reasons, why you should not override the paint method of top level containers ;)

answered Feb 11, 2019 by developer_1
• 3,320 points

Related Questions In Java

+1 vote
3 answers

What is the syntax to declare and initialize an array in java?

You can use this method: String[] strs = ...READ MORE

answered Jul 25, 2018 in Java by samarth295
• 2,220 points
3,139 views
0 votes
2 answers

How can I convert a String variable to a primitive int in Java

 Here are two ways illustrating this: Integer x ...READ MORE

answered Aug 20, 2019 in Java by Sirajul
• 59,230 points
1,888 views
0 votes
5 answers

How to compare Strings in Java?

String fooString1 = new String("foo"); String fooString2 = ...READ MORE

answered Jul 12, 2018 in Java by Daisy
• 8,120 points
2,154 views
+1 vote
2 answers

How to generate random integers within specific range in Java?

You can achieve that concisely in Java: Random ...READ MORE

answered Jul 25, 2018 in Java by samarth295
• 2,220 points
959 views
+5 votes
4 answers

How to execute a python file with few arguments in java?

You can use Java Runtime.exec() to run python script, ...READ MORE

answered Mar 27, 2018 in Java by DragonLord999
• 8,450 points

edited Nov 7, 2018 by Omkar 79,310 views
+1 vote
1 answer

How to handle drop downs using Selenium WebDriver in Java

First, find an XPath which will return ...READ MORE

answered Mar 27, 2018 in Selenium by nsv999
• 5,500 points
7,921 views
0 votes
1 answer

What are the differences between getText() and getAttribute() functions in Selenium WebDriver?

See, both are used to retrieve something ...READ MORE

answered Apr 5, 2018 in Selenium by nsv999
• 5,500 points
16,941 views
0 votes
1 answer

Selenium JARS(Java) missing from downloadable link

Nothing to worry about here. In the ...READ MORE

answered Apr 5, 2018 in Selenium by nsv999
• 5,500 points

edited Aug 4, 2023 by Khan Sarfaraz 4,356 views
0 votes
3 answers

Check if a String is numeric in Java

Java 8 Lambda Expression is used: String someString ...READ MORE

answered Sep 3, 2018 in Java by Daisy
• 8,120 points
3,357 views
0 votes
3 answers

How can I add new elements to an Array in Java

String[] source = new String[] { "a", ...READ MORE

answered Sep 19, 2018 in Java by Sushmita
• 6,910 points
11,430 views
webinar REGISTER FOR FREE WEBINAR X
REGISTER NOW
webinar_success Thank you for registering Join Edureka Meetup community for 100+ Free Webinars each month JOIN MEETUP GROUP