Fixing a NoClassDefFoundError
- by Chris Okyen
I have some code:
package ftc;
import java.util.Scanner;
public class Fer_To_Cel {
public static void main(String[] argv)
{
// Scanner object to get the temp in degrees Farenheit
Scanner keyboard = new Scanner(System.in);
boolean isInt = true; // temporarily put as true in case the user enters a valid int the first time
int degreesF = 0; // initialy set to 0
do
{
try
{
// Input the temperature text.
System.out.print("\nPlease enter a temperature (integer number, no fractional part) in degrees Farenheit: ");
degreesF = Integer.parseInt(keyboard.next()); // Get user input and Assign the far. temperature variable, which is casted from String to int.
}
// Let the user know in a user friendly notice that the value entered wasnt an int ( give int value range ) , and then give error log
catch(java.lang.Exception e)
{
System.out.println("Sorry but you entered a non-int value ( needs to be between ( including ) -2,147,483,648 and 2,147,483,647 ).. \n");
e.printStackTrace();
isInt = false;
}
}
while(!isInt);
System.out.println(""); // print a new line.
final int degreesC = (5*(degreesF-32)/9); // convert the degrees from F to C and store the resulting expression in degreesC
// Print out a newline, then print what X degrees F is in Celcius.
System.out.println("\n" + degreesF + " degrees Farenheit is " + degreesC + " degrees Celcius");
}
}
And The following error:
C:\Program Files\Java\jdk1.7.0_06\bin>java Fer_To_Cel
Exception in thread "main" java.lang.NoClassDefFoundError: Fer_To_Cel (wrong name: ftc/Fer_To_Cel)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14
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$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:480)
The code compiled without compile errors, but presented errors during execution.
Which leads me to two questions.
I know Errors can be termed Compiler, Runtime and Logic Errors, but the NoClassDefFoundError inherits java.lang.LinkageError. Does that make it a Linker error, being niether of the three types of errors I listed,
If I am right this is the answer. For someone else who obtains the singular .java file and compiles it, would this be the only way to solve this problem? Or can I (should I ) do/have done something to fix this problem? Basically, based on a basis of programming, is this a fault of me as the writer? Could this be done once on, my half and be distributed and not needed be done again?
