How do I draw a string in Java 2D?

By I Wayan Saryada in 2D API, Core API 0 Comment

The code snippet below show you how to draw a string using Graphics2D. The drawString() method accept the string to be drawn and their x and y coordinate. Here you can also see how to set the antialiasing mode using the setRenderingHint() method.

package org.kodejava.awt.geom;

import javax.swing.*;
import java.awt.*;

public class DrawString extends JPanel {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setTitle("Draw String Demo");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.add(new DrawString());
        frame.pack();
        frame.setSize(420, 300);
        frame.setVisible(true);
    }

    @Override
    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;

        // Define rendering hint, font name, font style and font size
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setFont(new Font("Segoe Script", Font.BOLD + Font.ITALIC, 40));
        g2.setPaint(Color.ORANGE);

        // Draw Hello World String
        g2.drawString("Hello World!", 50, 100);
    }
}

Run the snippet, and you’ll see the following screen:

Draw 2D String

Draw 2D String

How do I define a servlet with @WebServlet annotation?

By I Wayan Saryada in Servlet 0 Comment

Annotations is one new feature introduces in the Servlet 3.0 Specification. Previously to declare servlets, listeners or filters we must do it in the web.xml file. Now, with the new annotations feature we can just annotate servlet classes using the @WebServlet annotation.

package org.kodejava.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(
        name = "HelloAnnotationServlet",
        urlPatterns = {"/hello", "/helloanno"},
        asyncSupported = false,
        initParams = {
                @WebInitParam(name = "name", value = "admin"),
                @WebInitParam(name = "param1", value = "value1"),
                @WebInitParam(name = "param2", value = "value2")
        }
)
public class HelloAnnotationServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");

        PrintWriter out = response.getWriter();
        out.write("<html><head><title>WebServlet Annotation</title></head>");
        out.write("<body>");
        out.write("<h1>Servlet Hello Annotation</h1>");
        out.write("<hr/>");
        out.write("Welcome " + getServletConfig().getInitParameter("name"));
        out.write("</body></html>");
        out.close();
    }
}

After you’ve deploy the servlet you’ll be able to access it either using the /hello or /helloanno url.

The table below give brief information about the attributes accepted by the @WebServlet annotation and their purposes.

ATTRIBUTE DESCRIPTION
name The servlet name, this attribute is optional.
description The servlet description and it is an optional attribute.
displayName The servlet display name, this attribute is optional.
urlPatterns An array of url patterns use for accessing the servlet, this attribute is required and should at least register one url pattern.
asyncSupported Specifies whether the servlet supports asynchronous processing or not, the value can be true or false.
initParams An array of @WebInitParam, that can be used to pass servlet configuration parameters. This attribute is optional.
loadOnStartup An integer value that indicates servlet initialization order, this attribute is optional.
smallIcon A small icon image for the servlet, this attribute is optional.
largeIcon A large icon image for the servlet, this attribute is optional.

Maven dependencies

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>4.0.1</version>
</dependency>

Maven Central

How do I create a gradient paint in Java 2D?

By I Wayan Saryada in 2D API, Core API 0 Comment

To change the color of a graphics shape we can use the setPaint() method. For a simple coloring we can pass the color object into this method, such as Color.RED or Color.GREEN.

If you want to paint with a gradient paint you can use the GradientPaint class. This class provides a way to fill a shape with a linear color gradient pattern. To create a gradient color pattern you can pass the following parameter to the object constructor.

  • x1: x coordinate of the first specified point in user space
  • y1: y coordinate of the first specified point in user space
  • color1: color at the first specified point
  • x2: x coordinate of the second specified point in user space
  • y2: y coordinate of the second specified point in user space
  • color2: color at the second specified point
package org.kodejava.awt.geom;

import javax.swing.*;
import java.awt.*;
import java.awt.geom.Rectangle2D;

public class GradientPaintDemo extends JComponent {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Gradient Paint Demo");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.getContentPane().add(new GradientPaintDemo());
        frame.pack();
        frame.setSize(new Dimension(420, 350));
        frame.setVisible(true);
    }

    @Override
    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;

        GradientPaint blackToGray = new GradientPaint(50, 50, Color.BLACK,
                300, 100, Color.LIGHT_GRAY);
        g2.setPaint(blackToGray);
        g2.fill(new Rectangle2D.Double(50, 50, 300, 100));

        GradientPaint blueToBlack = new GradientPaint(0, 0, Color.BLUE,
                400, 400, Color.BLACK);
        g2.setPaint(blueToBlack);
        g2.fill(new Rectangle2D.Double(50, 160, 300, 100));
    }
}

This code snippet produce the following output:

2D Gradient Paint Demo

2D Gradient Paint Demo

How do I define stroke when drawing a shape in Java 2D?

By I Wayan Saryada in 2D API, Core API 0 Comment 
package org.kodejava.awt.geom;

import javax.swing.*;
import java.awt.*;
import java.awt.geom.Line2D;

public class DrawStrokeDemo extends JComponent {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Draw Stroke Demo");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.getContentPane().add(new DrawStrokeDemo());
        frame.pack();
        frame.setSize(new Dimension(420, 200));
        frame.setVisible(true);
    }

    @Override
    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;

        float[] strokes = {1, 2, 3, 4, 5, 6};
        for (float stroke : strokes) {
            g2.setStroke(new BasicStroke(stroke));
            g2.draw(new Line2D.Float(50, stroke * 20, 350, stroke * 20));
        }
    }
}

This code snippet produce the following output:

Draw 2D Stroke

Draw 2D Stroke

How do I create a dashed stroke in Java 2D?

By I Wayan Saryada in 2D API, Core API 0 Comment 
package org.kodejava.awt.geom;

import javax.swing.*;
import java.awt.*;
import java.awt.geom.RoundRectangle2D;

public class DrawDashedStroke extends JComponent {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Draw Dashed Stroke Demo");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.getContentPane().add(new DrawDashedStroke());
        frame.pack();
        frame.setSize(new Dimension(420, 250));
        frame.setVisible(true);
    }

    @Override
    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;
        float[] dash = {10.0f, 5.0f, 3.0f};

        // Creates a dashed stroke
        Stroke dashed = new BasicStroke(2.0f, BasicStroke.CAP_BUTT,
                BasicStroke.JOIN_MITER, 10.0f, dash, 0.0f);

        g2.setStroke(dashed);
        g2.setPaint(Color.RED);
        g2.draw(new RoundRectangle2D.Double(50, 50, 300, 100, 10, 10));
    }
}

This code snippet produce the following output:

Draw 2D Dashed Stroke

Draw 2D Dashed Stroke