NoClassDefFoundError when trying to parse JSON with JSON simple

Question

I use JSON simple to parse JSON and I get NoClassDefFoundError when trying to create JSONParser object.

import org.json.simple.JSONObject;
import org.json.simple.JSONArray;
import org.json.simple.parser.JSONParser;
...
JSONParser parser = new JSONParser();

I compile program with command:

javac MyProgram.java -cp json-simple-1.1.1.jar

And it compiles fine. But when I execute program with this command:

java MyProgram

I get NoClassDefFoundError

What am I doing wrong?

EDIT:
Full error:

Exception in thread "main" java.lang.NoClassDefFoundError: org/json/simple/parser/JSONParser
        at getNotesFromNoter.sendPost(getNotesFromNoter.java:53)
        at getNotesFromNoter.main(getNotesFromNoter.java:14)
Caused by: java.lang.ClassNotFoundException: org.json.simple.parser.JSONParser
        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)
        ... 2 more

Answer 1

You're not including the Simple JSON jar file in your classpath when running. You want:

// Unix
java -cp .:json-simple-1.1.1.jar MyProgram

// Windows
java -cp .;json-simple-1.1.1.jar MyProgram

(The : or ; is the path separator for the relevant operating system.)

When you compile Java and specify a classpath, that's just telling the compiler about the classes to compile against - it doesn't include the library in the result of the compilation, so you still need to specify the classpath in order to run the code, too.