NoClassDefFound Error! Please Help!

[ItsRoland]

I'm getting the NoClassDefFound Error when running this. Please note I'm very new to java.
Heres my code:

class DoMath {
	

	
	public static void main(String[] arguents){
	
	double velocity = 0;
	double accel = 0;
	double time = 0;
	
	
	System.out.println("Please enter the value for acceleration"); //promts user to input value for velocity
	
	double input = accel ; //accepts user input for acceleration
	
	System.out.println("Please enter the value for time in free fall"); //promts user to input value for time
	
	input = time ; //accepts user input for time
	
	velocity = 0.5 * accel * time ;
	
	System.out.println(velocity);
}
}

Heres the full error code:
Exception in thread "main" java.lang.NoClassDefFoundError: gravcalc (wrong name: gravcalc/gravcalc)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java :800)
at java.security.SecureClassLoader.defineClass(Secure ClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader .java:449)
at java.net.URLClassLoader.access$100(URLClassLoader. java:71)
at java.net.URLClassLoader$1.run(URLClassLoader.java: 361)
at java.net.URLClassLoader$1.run(URLClassLoader.java: 355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:4 25)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 58)
at sun.launcher.LauncherHelper.checkAndLoadMain(Launc herHelper.java:482)


------------------
(program exited with code: 1)
Press return to continue



Any help is appreciated!

[Norm]

Please edit your post and wrap the code in code tags.

getting the NoClassDefFound Error

Please copy the full text of the error message and paste it here. It has important info about the error.

[ItsRoland]

added the full error message.

[Norm]

Exception in thread "main" java.lang.NoClassDefFoundError: gravcalc (wrong name: gravcalc/gravcalc)

What command did you enter to get that message?
How is that error message related to the posted code? The posted code has class: DoMath; the error message has class: gravcalc