Graphs in Java

Cartesian Plane

The Cartesian Plane is the usual graph surface we are taught in school.
It consists of the x and y axes.

In Java, drawing is done using the java.awt and/or javax.swing libraries.

With java.awt, drawing is usually done using an Applet or Canvas component.
With javax.swing, drawing is usually done using a JApplet or JPanel component.

Whichever way, there is a subtle difference between the way we use graphs and the Java drawing components:
The y-axis of the Java drawing components is measured from the top and increases as you move downwards.

Drawing on the Java Canvas

In Java, the canvas component would represent something like a graph book; and this graph book is plotted or drawn on using code.

Create a new java project; call it Dymetric.
Create a new java class file; call it Facet.
Create a second java class file; call it CanvasFeel.

Type out the adjoining Java algorithm to see what the canvas component feels like.

Main Class

package dymetric;

public class Dymetric {

    public static void main(String[] args) {
        Facet lcd = new Facet();
        lcd.setVisible(true);
    }

}

Window Display

package dymetric;

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

public class Facet extends JFrame {

    private Container face;
    private CanvasFeel canvas;
    private ImageIcon logo;

    public Facet() {
        // Give our window a title
        super("A window that will hold a Canvas");
        // set window start points and dimensions
        setSize(780,400);
        // close the window when told to
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(true); // should this window be resizable?

        // It'll be nice to have our own logo (feel free to use yours)
        logo = new ImageIcon(getClass().getResource("studyingPays.png"));
        this.setIconImage(logo.getImage());

        face = this.getContentPane();
        // background colour - may not be necessay since our canvas will have a colour of its own
        face.setBackground(Color.PINK);


        canvas = new CanvasFeel();
        // using the default layout manager
        face.add(canvas, BorderLayout.NORTH);
    }
}

Java code for Canvas class

package dymetric;

import java.awt.*;

public class CanvasFeel extends Canvas {
    public CanvasFeel() {
        setBackground(Color.YELLOW);
    }
}

Important: Get the logo image(.png) used in the code here and save it to the same folder(directory) as your code files.
For NetBeans, this folder should be C:\Users\user_name\Documents\NetBeansProjects\Dymetric\src\dymetric.

Note: The code module for our main class will remain the same for the rest of the demonstrations in this category.
Hence it will be left out hence forth.

Drawing Reference

For a thorough explanation of drawing graphics in Java, please see the following link:
(Just to mention; the tutorial at this link makes heavy use of applets which are no longer supported - deprecated - by modern browsers. To try out the lessons shown, you can run the applets as stand alone programs by changing the following lines in our facet class from

private CanvasFeel canvas;
canvas = new CanvasFeel();
face.add(canvas, BorderLayout.NORTH);
to
private AppletClassName a_var_name;
a_var_name = new AppletClassName();
face.add(a_var_name, BorderLayout.NORTH);

)

David J. Eck's Introduction to Programming Using Java - largely apt for Java beginners; Knock your head out!!