Thread: Help With Applets

Hi im using applet for my project to draw road maps with the latitude longitude information.But im having a problem in tat.my values read
minX=40.1128
maxX=40.1150
minY=30.1145
maxY=30.1138

when i draw a line i get only a dot.can i give my own scale to the applet or do u have any other ideas ???plz help thanks ..............

Without an SSCCE one can only guess that you are trying to draw floating point values to a panel which can only draw integers.

This is my code

 import java.sql.*;
 import java.sql.DriverManager;
 import java.sql.ResultSet;
 import java.awt.geom.Line2D;
 import java.awt.Graphics2D;
 import java.sql.Statement;
 import java.applet.*;
 import java.awt.*;
 
 public class ConnectSQLite extends Applet
 {
      int x;
  float y;
  Graphics gr;
  Connection connection = null;
     ResultSet resultSet = null;
     Statement statement = null;
 
 
 
 
    try
     {
         Class.forName("org.sqlite.JDBC");
         connection = DriverManager.getConnection("jdbc:sqlite:///home/student/Desktop//roads.db");
         statement = connection.createStatement();
         resultSet = statement
                 .executeQuery("SELECT * FROM coord");
 
         while (resultSet.next())
         {
              System.out.println("id:"+ resultSet.getString("id"));
              System.out.println("minX:"+ resultSet.getString("minX"));
              System.out.println("minY:"+ resultSet.getString("minY"));
 
               float x1=Float.parseFloat(resultSet.getString("minX"));
               float y1=Float.parseFloat(resultSet.getString("minY"));
               float x2=Float.parseFloat(resultSet.getString("maxX"));
               float y2=Float.parseFloat(resultSet.getString("maxY"));
 
		   //Drawing lines with floating point coordinates
 
 
               BasicStroke ll=new BasicStroke(2.0f);
 
               Graphics2D g2=(Graphics2D)this.getGraphics();
               g2.setStroke(ll);
               g2.draw(new Line2D.Float(x1*Applet.WIDTH, y1*Applet.HEIGHT, x2*Applet.WIDTH, y2*Applet.HEIGHT));
 
          }
     }
     catch (Exception e)
     {
         javax.swing.JOptionPane.showMessageDialog(null,e);
     }
 
 
 
 }

One post is enough....your other post has been deleted. For future reference, please do not post your question twice to the forums.

Do not call getGraphics to draw to a Component. Override the paint method (for awt) or paintComponent (for Swing) and do your drawing there. If you have small lines, then scale the drawing by either altering the values, or calling graphics.scale

sorry that was my first post so i i was not familiar with thread creation...

thanks for ur reply ill look into it and reply

If you have small lines, then scale the drawing by either altering the values, or calling graphics.scale

hi i have tried scaling but i get divide by zero exception.....can u plz give an elaborate idea???

Originally Posted by mukilan

hi i have tried scaling but i get divide by zero exception.....can u plz give an elaborate idea???

I recommend posting an SSCCE demonstrating the problem. Division by zero seems more like a logic problem that can't be resolved without a code example.

ok this is my test data

id:1000
minX:43.0999984741211
minY:80.0999984741211
minX:43.0999984741211
minY:80.1019973754883
id:1001
minX:43.101001739502
minY:80.0999984741211
minX:43.101001739502
minY:80.1019973754883
id:1002
minX:43.1004981994629
minY:80.0999984741211
minX:43.100700378418
minY:80.1019973754883
id:1003
minX:43.0999984741211
minY:80.0999984741211
minX:43.1004981994629
minY:80.0999984741211
id:1004
minX:43.1004981994629
minY:80.0999984741211
minX:43.101001739502
minY:80.0999984741211
id:1005
minX:43.0999984741211
minY:80.1019973754883
minX:43.100700378418
minY:80.1019973754883
id:1006
minX:43.100700378418
minY:80.1019973754883
minX:43.101001739502
minY:80.1019973754883


and my code is

 import java.sql.*;
 import java.sql.DriverManager;
 import java.sql.ResultSet;
 import java.awt.geom.Line2D;
 import java.awt.Graphics2D;
 import java.sql.Statement;
 import java.applet.*;
 import java.awt.*;
 
 public class ConnectSQLite extends Applet
 {
      int x;
  float y;
  Graphics gr;
  Connection connection = null;
     ResultSet resultSet = null;
     Statement statement = null;
 
    @Override
  public void init()
  {
try
     {
         Class.forName("org.sqlite.JDBC");
         connection = DriverManager.getConnection("jdbc:sqlite:///home/foss/Desktop//roads.db");
         statement = connection.createStatement();
         resultSet = statement
                 .executeQuery("SELECT * FROM coord");
 
 
     }
     catch (Exception e)
     {
         javax.swing.JOptionPane.showMessageDialog(null,e);
     }
  }
 
 
    @Override
    public void paint(Graphics g)
    {
            super.paintComponents(g);
        try{
         while (resultSet.next())
         {
              //omit this while running as i have procided the out put of this as the testdata.
 
              System.out.println("id:"+ resultSet.getString("id"));
              System.out.println("minX:"+ resultSet.getString("minX"));
              System.out.println("minY:"+ resultSet.getString("minY"));
              System.out.println("minX:"+ resultSet.getString("maxX"));
              System.out.println("minY:"+ resultSet.getString("maxY"));
 
               double x1=Double.parseDouble(resultSet.getString("minX"));
               double y1=Double.parseDouble(resultSet.getString("minY"));
               double x2=Double.parseDouble(resultSet.getString("maxX"));
               double y2=Double.parseDouble(resultSet.getString("maxY"));
             BasicStroke ll=new BasicStroke(1);
 Graphics2D g2=(Graphics2D)g;
               g2.setStroke(ll);
 
 //this function doesnt work for me as i wanted plz provide me with a appropriate value for my test data.
               g2.scale(2.0,2.0);
               g2.draw(new Line2D.Double(x1, y1, x2, y2));
 
          }
        }
        catch(Exception e)
        {
            javax.swing.JOptionPane.showMessageDialog(null,e);
        }
 
        }  
    }

@ kevin

i have provided a test data for my problem in my second post.im just trying to read the road coordinates from a file(latitude,longitude endpoints) and trying to plot it in my screen.since the distance between the two points are very small im just getting a dot instead of a road network. hope this helps u to figure out wat im saying........

Pixels are pixels, 1=1 and 1.0001=1. So providing floating points that close together will boil down to a single point in a real application.You need to transform and scale the coordinates appropriately so they fit and scale to what you want, and doing so is highly dependent upon the result you want. Have a look at this turorial Java2d: Transformations