Histogram class

Histogram.java

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

public class Histogram extends JPanel {
    
    // Count the occurrences of 26 letters
    private int[] count;
    
    /** 
     * Set the count and display histogram
     * @param count 
     */
    public void showHistogram(int[] count) {
        this.count = count;
        repaint();
    }
    
    @Override
    /** Paint the histogram */
    protected void paintComponent(Graphics g) {
        if (count == null) {
            return;
        }
        
        super.paintComponent(g);
        
        // Find the panel size and bar width and interval dynamically
        int width = getWidth();
        int height = getHeight();
        int interval = (width - 40) / count.length;
        int individualWidth = (int) (((width - 40) / 26) * 0.8);
        
        // Find the maximum count. The maximum count has the highest bar
        int maxCount = 0;
        for (int i = 0; i < count.length; i++) {
            if (maxCount < count[i])
                maxCount = count[i];
        }
        
        // x is the start position for the first bar in the histogram
        int x = 30;
        
        // Draw a horizontal base line
        g.drawLine(10, height - 45, width - 10, height - 45);
        g.setColor(Color.magenta);
        for (int i = 0; i < count.length; i++) {
            // Find the bar height
            int barHeight = (int) 
                    (((double) count[i] / (double) maxCount) * (height - 45));
            // Display a bar (i.e., rectangle)
            g.fillRect(x, height - 45 - barHeight, individualWidth, barHeight);
            
            // Display a letter under the base line
            g.drawString((char)(65 + i) + "", x, height - 30);
            
            // Move x for displaying the next character
            x += interval;
        }
    }
    
    @Override
    public Dimension getPreferredSize() {
        return new Dimension(300, 300);
    }
    
}