The best way to predict the future is to create it.


What’s the error

Error 1: Cannot find symbol class Generated

If you are using some libraries to generate source code, such as MapStruct, QueryDSL,some annotation wil be processed and those java classed java sources will be saved under target folder.

However, if you getting errors in thsoe generated class, such as cannot find symbol calss Generated, this is acatualy one class in javax.annotation.processing package.

here is the error screenshot:


Firslty you may be tempted to add one dependency in maven, like below one


Generally this should not work (but if it do to you, congradulations and you can close this page now. :-) )

If not, let’s keep reading.

The root cause is actaully this Generated is introduced from JDK 9. So you need to make sure your project is using JDK 9+.

So go to check your pom.xml (maven) to make sure no JDK 8 but at lease 9, such as below example:

Error 2: cannot find symbol class var

If you are using new Java keyword var and combiled good, however get following error in runtime;

java: as of release 10, ‘var’ is a restricted local variable type and cannot be used for type declarations or as the element type of an array

The error may look like below:

You may think this is an easy fix and try to update JDK version in maven pom.xml, unfortuantely it may not work.


If you spot in more details you may realized this is compile good but failed in run. As you know, Java will compile to byte code and JVM will use the byte code to spin up a new Java process. So the error should fall in the byte code.

This can be fixed by updating following config in your IDE:

go to Build->Compiler->Java Compiler-> Target bytecode version