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…

Accepted Answer

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.

NoClassDefFoundError when trying to parse JSON with JSON simple

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