Graph implemented

src/main/java/DrawGraph.java

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+import java.awt.BasicStroke;
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Point;
+import java.awt.RenderingHints;
+import java.awt.Stroke;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+import javax.swing.*;
+
+@SuppressWarnings("serial")
+public class DrawGraph extends JPanel {
+    private static final int MAX_SCORE = 20;
+    private static final int PREF_W = 800;
+    private static final int PREF_H = 650;
+    private static final int BORDER_GAP = 30;
+    private static final Color GRAPH_COLOR = Color.black;
+    private static final Color GRAPH_POINT_COLOR = new Color(150, 50, 50, 180);
+    private static final Stroke GRAPH_STROKE = new BasicStroke(1f);
+    private static final int GRAPH_POINT_WIDTH = 2;
+    private static final int Y_HATCH_CNT = 10;
+    private List<Double> scores;
+
+    public DrawGraph(List<Double> scores) {
+        this.scores = scores;
+    }
+
+    @Override
+    protected void paintComponent(Graphics g) {
+        super.paintComponent(g);
+        Graphics2D g2 = (Graphics2D)g;
+        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+
+        double xScale = ((double) getWidth() - 2 * BORDER_GAP) / (scores.size() - 1);
+        double yScale = ((double) getHeight() - 2 * BORDER_GAP) / (MAX_SCORE - 1);
+
+        List<Point> graphPoints = new ArrayList<Point>();
+        for (int i = 0; i < scores.size(); i++) {
+            int x1 = (int) (i * xScale + BORDER_GAP);
+            int y1 = (int) ((MAX_SCORE - scores.get(i)) * yScale + BORDER_GAP);
+            graphPoints.add(new Point(x1, y1));
+        }
+
+        // create x and y axes
+        g2.drawLine(BORDER_GAP, getHeight() - BORDER_GAP, BORDER_GAP, BORDER_GAP);
+        g2.drawLine(BORDER_GAP, getHeight() - BORDER_GAP, getWidth() - BORDER_GAP, getHeight() - BORDER_GAP);
+
+        // create hatch marks for y axis.
+        for (int i = 0; i < Y_HATCH_CNT; i++) {
+            int x0 = BORDER_GAP;
+            int x1 = GRAPH_POINT_WIDTH + BORDER_GAP;
+            int y0 = getHeight() - (((i + 1) * (getHeight() - BORDER_GAP * 2)) / Y_HATCH_CNT + BORDER_GAP);
+            int y1 = y0;
+            g2.drawLine(x0, y0, x1, y1);
+        }
+
+        // and for x axis
+        for (int i = 0; i < scores.size() - 1; i++) {
+            int x0 = (i + 1) * (getWidth() - BORDER_GAP * 2) / (scores.size() - 1) + BORDER_GAP;
+            int x1 = x0;
+            int y0 = getHeight() - BORDER_GAP;
+            int y1 = y0 - GRAPH_POINT_WIDTH;
+            g2.drawLine(x0, y0, x1, y1);
+        }
+
+        Stroke oldStroke = g2.getStroke();
+        g2.setColor(GRAPH_COLOR);
+        g2.setStroke(GRAPH_STROKE);
+        for (int i = 0; i < graphPoints.size() - 1; i++) {
+            int x1 = graphPoints.get(i).x;
+            int y1 = graphPoints.get(i).y;
+            int x2 = graphPoints.get(i + 1).x;
+            int y2 = graphPoints.get(i + 1).y;
+            g2.drawLine(x1, y1, x2, y2);
+        }
+
+        g2.setStroke(oldStroke);
+        g2.setColor(GRAPH_POINT_COLOR);
+        for (int i = 0; i < graphPoints.size(); i++) {
+            int x = graphPoints.get(i).x - GRAPH_POINT_WIDTH / 2;
+            int y = graphPoints.get(i).y - GRAPH_POINT_WIDTH / 2;;
+            int ovalW = GRAPH_POINT_WIDTH;
+            int ovalH = GRAPH_POINT_WIDTH;
+            g2.fillOval(x, y, ovalW, ovalH);
+        }
+    }
+
+    @Override
+    public Dimension getPreferredSize() {
+        return new Dimension(PREF_W, PREF_H);
+    }
+
+    private static void createAndShowGui() {
+        List<Double> scores = new ArrayList<>();
+        Random random = new Random();
+        int maxDataPoints = 16;
+        double maxScore = 20.0;
+        for (int i = 0; i < maxDataPoints ; i++) {
+            scores.add(random.nextDouble()*maxScore);
+        }
+        DrawGraph mainPanel = new DrawGraph(scores);
+
+        JFrame frame = new JFrame("DrawGraph");
+        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        frame.getContentPane().add(mainPanel);
+        frame.pack();
+        frame.setLocationByPlatform(true);
+        frame.setVisible(true);
+    }
+
+    public static void main(String[] args) {
+        SwingUtilities.invokeLater(new Runnable() {
+            public void run() {
+                createAndShowGui();
+            }
+        });
+    }
+}