Question

Following program runs fine with Netbeans IDE but when i try to run from command prompt i get

Exception in thread "main" java.lang.NoClassDefFoundError: Gcd (wrong name: algo
rithms/Gcd)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.access$100(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)

package algorithms;

public class Gcd {

public static int ComputeGcd(int number1, int number2){
    if(number2 == 0){ return number1;}
    else{
         int remainder = number1 % number2;
         return ComputeGcd(number2,remainder);
    }
}


public static void main(String[] args) {

    int a = 32;
    int b = 12;
    System.out.println(ComputeGcd(a,b));

} 

}

Answer 1

You should be in the src directory, running these commands:

...\src> javac algorithms\Gcd.java
...\src> java algorithms.Gcd

(You don’t have to compile from that directory, but I would suggest you do so.)

The java command takes the fully-qualified class name, which includes the package name.