Drawing equilateral triangle using drawpolygon method?

Question

How can I draw an equilateral triangle using the graphics method especially the draw polygon method. My issue is that to make an equilateral triangle I need the square root 3/2 and the drawPolygon method I can only use int[],int[],int, the compiler will not let me double because it differ in lengh.

Any help is appreciated.

         import java.awt.*;

          public class Triangle extends Shape {
         // Instance variables
           private int leng;


       // Constructor
       public Triangle(int x, int y, Color color,
               int leng) {
               super(x, y, color);
               this.leng=leng;
         }
        // Instance methods
           public void draw(Graphics g) {
               double[] Xcoord = { getX(), getX() + leng, getX() + leng / 2};
             double[] Ycoord = { getY(), getY(), getY()*(1.0+ Math.sqrt(3) / (2.0))};
              g.drawPolygon(Xcoord,Ycoord,3);

       }

        public int getHeight() {
              return leng;
        }

         public int getWidth() {
             return leng;
           }
           }

Use a consistent and logical indent for code blocks. The indentation of the code is intended to help people understand the program flow. — Andrew Thompson, Nov 16 '13 at 16:32
What's the issue? You can't use floating point values because pixel coordinates cannot be fractional. Just round the double value(s) and cast them to int. — Radiodef, Nov 16 '13 at 16:37

score 2 · Answer 1 · edited May 23 '17 at 12:28

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Polygon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class JRisk {

    private JFrame mainMap;
    private Polygon poly;

    public JRisk() {

        initComponents();

    }

    private void initComponents() {

        mainMap = new JFrame();
        mainMap.setResizable(false);

        mainMap.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        int xPoly[] = {150, 250, 325, 375, 450, 275, 100};
        int yPoly[] = {150, 100, 125, 225, 250, 375, 300};

        poly = new Polygon(xPoly, yPoly, xPoly.length);
        JPanel p = new JPanel() {
            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.setColor(Color.BLUE);
                g.drawPolygon(poly);
            }

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(800, 600);
            }
        };
        mainMap.add(p);
        mainMap.pack();
        mainMap.setVisible(true);

    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new JRisk();
            }
        });
    }
}

This was found from about drawing a Polygon in java after searching in google.

Drawing equilateral triangle using drawpolygon method?

1 Answers1