How to Create a Simple Line Graph in Java

What is the process for drawing a simple line graph in Java?

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

public class LineGraph extends JPanel {
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.BLUE);
        g.drawLine(50, 300, 200, 100); // Example line
        g.drawLine(200, 100, 350, 200);
        g.drawLine(350, 200, 500, 50);
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        LineGraph graph = new LineGraph();
        frame.add(graph);
        frame.setSize(600, 400);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

Drawing a simple line graph in Java can be accomplished using Java's AWT (Abstract Window Toolkit) and Swing libraries. This answer provides a comprehensive approach including the creation of a JFrame, the implementation of a JPanel, and the use of graphics methods to draw lines effectively on a canvas.

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

public class LineGraph extends JPanel {
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.BLUE);
        g.drawLine(50, 300, 200, 100);
        g.drawLine(200, 100, 350, 200);
        g.drawLine(350, 200, 500, 50);
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        LineGraph graph = new LineGraph();
        frame.add(graph);
        frame.setSize(600, 400);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

Causes

• Lack of familiarity with Java GUI libraries
• Not understanding how to override paint methods
• Inadequate setup of JFrame or JPanel

Solutions

• Use Java Swing for GUI applications
• Override the paintComponent method in a JPanel to customize drawing
• Ensure the JFrame is set up properly to display the JPanel

Mistake: Forgetting to call super.paintComponent(g) in paintComponent method.

Solution: Always include super.paintComponent(g) to ensure proper rendering.

Mistake: Not setting the JFrame visible.

Solution: Ensure frame.setVisible(true) is called before testing the graph.

Mistake: Using incorrect coordinates or dimensions.

Solution: Double-check coordinates in the drawLine method for accurate representation.