Programming Forums > Application Development > Java

1stMan · Jul 11th, 2005, 10:46 AM

Hi,

I am trying to run a program in Java but it is not working. It compiles fine, but when i run it, it gives the error message:

"Exception in thread "main" java.lang.NoSuchMethodError: main"

Does anybody know what the problem is?

Thanks in advance.

Below is the code:

(Toggle Plain Text)

/*Mandel.java - Java Mandelbrot by MN Karthik. 
Any questions, comments, suggestions? You can contact me at mnkarthik@yahoo.com.
*/
import java.awt.Graphics;
import java.awt.Color;

public class Mandel extends java.applet.Applet {

    public void paint(Graphics g) {
  int sx=320;           //Screenwidth
  int sy=240;           //Screenheight
  double xmin=-2;       //smallest real value (x-axis)
  double xmax=1.25;     //largest real value (x-axis)
  double ymin=-1.25;    //smallest imaginary value (y-axis)
  double ymax=1.25;     //largest imaginary value (y-axis)
  double maxiter=512;       //Max number of iterations

  double old_x;         //temporary variable to store x-value
  double fx,fy;        
  int m;                //variable to store number of iterations

  double dx=(xmax-xmin)/sx; //how much to add for each x-pixel?
  double dy=(ymax-ymin)/sy; //how much to add for each y-pixel?

  int px;               //Variable storing current x-pixel
  int py=0;             //Variable storing current y-pixel
  double x;             //Variable storing current x-value
  double y=ymin;        //Variable storing current y-value

 g.setColor(Color.black);
 g.drawString("Rendering Mandelbrot..... please wait", 72, 220);
  while (py<sy) {
	 px=0;
	 x=xmin;
	 py++;
	 while (px<sx) {
		px++;

		fx=0;           
		fy=0;
		m=0;            
		do {
		  old_x=fx;      
		  fx=fx*fx-fy*fy+x;   
		  fy=2*old_x*fy+y;  
		  m++;                
		} while (((fx*fx+fy*fy)<4) && (m<maxiter)); 
	    if (m%2==0) g.setColor(Color.white);
	    if (m%3==0) g.setColor(Color.green);
	    if (m%4==0) g.setColor(Color.blue);
	    if (m%5==0) g.setColor(Color.red);
	    if (m%6==0) g.setColor(Color.yellow);
	    if (m%7==0) g.setColor(Color.cyan);
	    if (m%8==0) g.setColor(Color.magenta);
	    if (m%9==0) g.setColor(Color.orange);
	    if (m%10==0) g.setColor(Color.pink);
	    if (m%11==0) g.setColor(Color.gray);
	    if (m%12==0) g.setColor(Color.red);
	    if (m%13==0) g.setColor(Color.black);	g.drawLine(px-3,py-3,px+10,py+10);	 //the +10 adds a nice effect while rendering :)
	 x+=dx;
	 }
  y+=dy;
  }
  g.setColor(Color.black);
  g.drawString("Java Mandelbrot By MN Karthik", 3, 10);
    }
  public String getAppletInfo() {
    return "Java Mandelbrot by MN Karthik (mnkarthik@yahoo.com)";
  }
}

/*Mandel.java - Java Mandelbrot by MN Karthik. 
Any questions, comments, suggestions? You can contact me at mnkarthik@yahoo.com.
*/
import java.awt.Graphics;
import java.awt.Color;

public class Mandel extends java.applet.Applet {

    public void paint(Graphics g) {
  int sx=320;           //Screenwidth
  int sy=240;           //Screenheight
  double xmin=-2;       //smallest real value (x-axis)
  double xmax=1.25;     //largest real value (x-axis)
  double ymin=-1.25;    //smallest imaginary value (y-axis)
  double ymax=1.25;     //largest imaginary value (y-axis)
  double maxiter=512;       //Max number of iterations

  double old_x;         //temporary variable to store x-value
  double fx,fy;        
  int m;                //variable to store number of iterations

  double dx=(xmax-xmin)/sx; //how much to add for each x-pixel?
  double dy=(ymax-ymin)/sy; //how much to add for each y-pixel?

  int px;               //Variable storing current x-pixel
  int py=0;             //Variable storing current y-pixel
  double x;             //Variable storing current x-value
  double y=ymin;        //Variable storing current y-value

 g.setColor(Color.black);
 g.drawString("Rendering Mandelbrot..... please wait", 72, 220);
  while (py<sy) {
	 px=0;
	 x=xmin;
	 py++;
	 while (px<sx) {
		px++;

		fx=0;           
		fy=0;
		m=0;            
		do {
		  old_x=fx;      
		  fx=fx*fx-fy*fy+x;   
		  fy=2*old_x*fy+y;  
		  m++;                
		} while (((fx*fx+fy*fy)<4) && (m<maxiter)); 
	    if (m%2==0) g.setColor(Color.white);
	    if (m%3==0) g.setColor(Color.green);
	    if (m%4==0) g.setColor(Color.blue);
	    if (m%5==0) g.setColor(Color.red);
	    if (m%6==0) g.setColor(Color.yellow);
	    if (m%7==0) g.setColor(Color.cyan);
	    if (m%8==0) g.setColor(Color.magenta);
	    if (m%9==0) g.setColor(Color.orange);
	    if (m%10==0) g.setColor(Color.pink);
	    if (m%11==0) g.setColor(Color.gray);
	    if (m%12==0) g.setColor(Color.red);
	    if (m%13==0) g.setColor(Color.black);	g.drawLine(px-3,py-3,px+10,py+10);	 //the +10 adds a nice effect while rendering :)
	 x+=dx;
	 }
  y+=dy;
  }
  g.setColor(Color.black);
  g.drawString("Java Mandelbrot By MN Karthik", 3, 10);
    }
  public String getAppletInfo() {
    return "Java Mandelbrot by MN Karthik (mnkarthik@yahoo.com)";
  }
}

skuinders · Jul 11th, 2005, 11:13 AM

that is an applet, you don't run it from the command line. you need to run it in a web browser or applet viewer... make an html file that references the applet like this:

(Toggle Plain Text)

<applet code="Applet.class" width="200" height="200"/>

and open it in your browser.

Infinite Recursion · Jul 11th, 2005, 11:20 AM

beat me to it...

applications that run from the command line, look for the 'Main' function. The applets, look for 'Paint', etc.

varun_sud · Jul 25th, 2005, 7:30 AM

If u want to execute a program, the executable code must be inside main() method.
It seems u dont have any main() method.So u cannot execute a java program after compilation

Jul 11th, 2005, 10:46 AM	#1
1stMan Newbie Join Date: Jul 2005 Posts: 1 Rep Power: 0	Trying to run a java program Hi, I am trying to run a program in Java but it is not working. It compiles fine, but when i run it, it gives the error message: "Exception in thread "main" java.lang.NoSuchMethodError: main" Does anybody know what the problem is? Thanks in advance. Below is the code: (Toggle Plain Text) /Mandel.java - Java Mandelbrot by MN Karthik. Any questions, comments, suggestions? You can contact me at mnkarthik@yahoo.com. / import java.awt.Graphics; import java.awt.Color; public class Mandel extends java.applet.Applet { public void paint(Graphics g) { int sx=320; //Screenwidth int sy=240; //Screenheight double xmin=-2; //smallest real value (x-axis) double xmax=1.25; //largest real value (x-axis) double ymin=-1.25; //smallest imaginary value (y-axis) double ymax=1.25; //largest imaginary value (y-axis) double maxiter=512; //Max number of iterations double old_x; //temporary variable to store x-value double fx,fy; int m; //variable to store number of iterations double dx=(xmax-xmin)/sx; //how much to add for each x-pixel? double dy=(ymax-ymin)/sy; //how much to add for each y-pixel? int px; //Variable storing current x-pixel int py=0; //Variable storing current y-pixel double x; //Variable storing current x-value double y=ymin; //Variable storing current y-value g.setColor(Color.black); g.drawString("Rendering Mandelbrot..... please wait", 72, 220); while (py<sy) { px=0; x=xmin; py++; while (px<sx) { px++; fx=0; fy=0; m=0; do { old_x=fx; fx=fxfx-fyfy+x; fy=2old_xfy+y; m++; } while (((fxfx+fyfy)<4) && (m<maxiter)); if (m%2==0) g.setColor(Color.white); if (m%3==0) g.setColor(Color.green); if (m%4==0) g.setColor(Color.blue); if (m%5==0) g.setColor(Color.red); if (m%6==0) g.setColor(Color.yellow); if (m%7==0) g.setColor(Color.cyan); if (m%8==0) g.setColor(Color.magenta); if (m%9==0) g.setColor(Color.orange); if (m%10==0) g.setColor(Color.pink); if (m%11==0) g.setColor(Color.gray); if (m%12==0) g.setColor(Color.red); if (m%13==0) g.setColor(Color.black); g.drawLine(px-3,py-3,px+10,py+10); //the +10 adds a nice effect while rendering :) x+=dx; } y+=dy; } g.setColor(Color.black); g.drawString("Java Mandelbrot By MN Karthik", 3, 10); } public String getAppletInfo() { return "Java Mandelbrot by MN Karthik (mnkarthik@yahoo.com)"; } } /Mandel.java - Java Mandelbrot by MN Karthik. Any questions, comments, suggestions? You can contact me at mnkarthik@yahoo.com. / import java.awt.Graphics; import java.awt.Color; public class Mandel extends java.applet.Applet { public void paint(Graphics g) { int sx=320; //Screenwidth int sy=240; //Screenheight double xmin=-2; //smallest real value (x-axis) double xmax=1.25; //largest real value (x-axis) double ymin=-1.25; //smallest imaginary value (y-axis) double ymax=1.25; //largest imaginary value (y-axis) double maxiter=512; //Max number of iterations double old_x; //temporary variable to store x-value double fx,fy; int m; //variable to store number of iterations double dx=(xmax-xmin)/sx; //how much to add for each x-pixel? double dy=(ymax-ymin)/sy; //how much to add for each y-pixel? int px; //Variable storing current x-pixel int py=0; //Variable storing current y-pixel double x; //Variable storing current x-value double y=ymin; //Variable storing current y-value g.setColor(Color.black); g.drawString("Rendering Mandelbrot..... please wait", 72, 220); while (py<sy) { px=0; x=xmin; py++; while (px<sx) { px++; fx=0; fy=0; m=0; do { old_x=fx; fx=fxfx-fyfy+x; fy=2old_xfy+y; m++; } while (((fxfx+fyfy)<4) && (m<maxiter)); if (m%2==0) g.setColor(Color.white); if (m%3==0) g.setColor(Color.green); if (m%4==0) g.setColor(Color.blue); if (m%5==0) g.setColor(Color.red); if (m%6==0) g.setColor(Color.yellow); if (m%7==0) g.setColor(Color.cyan); if (m%8==0) g.setColor(Color.magenta); if (m%9==0) g.setColor(Color.orange); if (m%10==0) g.setColor(Color.pink); if (m%11==0) g.setColor(Color.gray); if (m%12==0) g.setColor(Color.red); if (m%13==0) g.setColor(Color.black); g.drawLine(px-3,py-3,px+10,py+10); //the +10 adds a nice effect while rendering :) x+=dx; } y+=dy; } g.setColor(Color.black); g.drawString("Java Mandelbrot By MN Karthik", 3, 10); } public String getAppletInfo() { return "Java Mandelbrot by MN Karthik (mnkarthik@yahoo.com)"; } }

Jul 11th, 2005, 11:13 AM	#2
skuinders Hobbyist Programmer Join Date: Jun 2005 Location: MA, US Posts: 204 Rep Power: 4	that is an applet, you don't run it from the command line. you need to run it in a web browser or applet viewer... make an html file that references the applet like this: (Toggle Plain Text) <applet code="Applet.class" width="200" height="200"/> <applet code="Applet.class" width="200" height="200"/> and open it in your browser. __________________ "A stupid man's report of what a clever man says can never be accurate, because he unconciously translates what he hears into something he can understand." - B. Russell http://web.bryant.edu/~srk2 Last edited by skuinders; Jul 11th, 2005 at 11:25 AM.

Jul 11th, 2005, 11:20 AM	#3
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,467 Rep Power: 8	beat me to it... applications that run from the command line, look for the 'Main' function. The applets, look for 'Paint', etc. __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."

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Jul 25th, 2005, 7:30 AM	#4
varun_sud Newbie Join Date: Jul 2005 Posts: 1 Rep Power: 0	If u want to execute a program, the executable code must be inside main() method. It seems u dont have any main() method.So u cannot execute a java program after compilation

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Programming Forums > Application Development > Java

Trying to run a java program