apache commons: ClassNotFoundException

问题

I'm trying to benefite from the EnumeratedIntegerDistribution() from org.apache.commons.math3.distribution, as shown below.

I'm working wiht jdk7 , on windows Xp, running from Command Line, in one and only project folder

I do:

download commons-math3-3.2 and unpackage it to my folder, where my java is.
compile my source with (no errors no warnings) javac -cp commons-math3-3.2/commons-math3-3.2.jar CheckMe.java
run java CheckMe

Here is the demonstration:

import java.lang.Math.*; import org.apache.commons.math3.distribution.EnumeratedIntegerDistribution;

public class CheckMe {

public CheckMe() {

    System.out.println("let us check it out"); 
    System.out.println(generate_rand_distribution (10));
}

private static int[] generate_rand_distribution (int count){
    int[] nums_to_generate          = new int[]    { -1,   1,    0  };
    double[] discrete_probabilities = new double[] { 0.4, 0.4, 0.2  };
    int[] samples = null;

    EnumeratedIntegerDistribution distribution = 
    new EnumeratedIntegerDistribution(nums_to_generate, discrete_probabilities);

    samples = distribution.sample (count);

    return (samples);
}   

public static void main (String args[]) { 
    System.out.println("Main: ");
    CheckMe  animation = new CheckMe();  
}

}

However I have got:

ClassNotFoundException: org.apache.commons.math3.distribution.EnumeratedIntegerDistribution at line 18 - the call for EnumeratedIntegerDistribution()

If I run as I was just advised (below):

    java -cp   commons-math3-3.2/commons-math3-3.2.jar  CheckMe

I get error: impossible to find the principle class CheckMe

Thanks a lot in advance for your advise.

回答1:

You need to specify the classpath both when you compile and when you run. So running

java CheckMe.java

is not enough. Also it should be

java CheckMe

assuming the class CheckMe is not in any package.

You need to execute

java -cp commons-math3-3.2/commons-math3-3.2.jar CheckMe

specifying the jars and other classes your CheckMe program needs.

来源：https://stackoverflow.com/questions/20954322/apache-commons-classnotfoundexception

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