MongoDB Java Driver MongoClient does not working when running

Question

I tried to use MongoDB java driver on Ubuntu 14.04.

The program indeed can pass the compile stage, but when running, it just has this error:

Exception in thread "main" java.lang.NoClassDefFoundError: com/mongodb/MongoClient
    at App.main(App.java:23)
Caused by: java.lang.ClassNotFoundException: com.mongodb.MongoClient
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    ... 1 more

My Java version is 1.7, and I indeed tried 1.6, but same error happened. My compile command is:

javac App.java -classpath mongo-java-driver-2.13.0.jar

And I run the program using command:

java App

Below is my Java code:

import com.mongodb.BasicDBObject;
import com.mongodb.BulkWriteOperation;
import com.mongodb.BulkWriteResult;
import com.mongodb.Cursor;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.MongoClient;
import com.mongodb.ParallelScanOptions;
import com.mongodb.MongoException;
import com.mongodb.ServerAddress;

import java.util.List;
import java.util.Set;

public class App
{
    public static void main(String[] args)
    {
        System.out.println("----- Program Start -----");
        try {
            MongoClient mongoClient = new MongoClient("localhost" , 27017);
            DB db = mongoClient.getDB("demo");
            System.out.println("Connect to database successfully.");

            DBCollection coll = db.getCollection("test");
            BasicDBObject doc = new BasicDBObject();
            for(int i = 0; i < 10; i++) {
                doc.append("A" + Integer.toString(i), 12.56);
            }

            System.out.println(doc);
        } catch (Exception e) {
            System.err.println(e.getClass().getName() + ": ");
            e.getMessage();
        }
    }
}

Could anyone please help? Thanks!!

Besides, the program will output line "----- Program Start -----", which means it runs into the main method. I also tried another version of driver but it still doesn't work. — LoGWRiTer, Feb 01 '15 at 01:01

score 2 · Accepted Answer · answered Feb 01 '15 at 01:06

2

The classpath is needed for both the compilation and the execution. The following invocation should work

java App -classpath mongo-java-driver-2.13.0.jar

answered Feb 01 '15 at 01:06

Frédéric Dumont

958
13
19

Thanks! But how can I make it work in maven? The problem originally happens in Maven actually. – LoGWRiTer Feb 01 '15 at 04:15
For that you'd want to make a so called fat jar. See another Stack Overflow [answer](http://stackoverflow.com/questions/16222748/how-to-build-fat-jar-with-maven). – Frédéric Dumont Feb 01 '15 at 06:13
Thanks. But today I still found the command do not work. The same error happened even when I use your command. – LoGWRiTer Feb 01 '15 at 17:23
I just changed to Windows platform and it seems to work with maven and Intellij. Any way, thank you very much! – LoGWRiTer Feb 01 '15 at 18:04
Sorry just forget to choose your answer. But the fat jar really works in Maven. Thanks for help! – LoGWRiTer Feb 02 '15 at 18:40

MongoDB Java Driver MongoClient does not working when running

1 Answers1