import javax.persistence.EntityManager error

Question

I have copied my project from pc to other and i got error

1. import javax.persistence.EntityManager; importjavax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import javax.persistence.Query;

the compiler doesn't know them, in the lib folder i added 3 jar from the local pc derby.jar eclipselink.jar and also javax.persistence_2.0.4.v201112161009.jar

what could be the reason

Answer 1

add two more Jar's that are

toplink-essentials.jar
toplink-essentials-agent.jar

Add this external jars to your project

Answer 2

at first refresh your project, if you copied with OS.

then maybo you have to add them to your build path.

1 right click on your project -> build path -> configure build path -> libraries -> add JARs...

2 select project/lib folder and choose the jars to add them.

3 click OK

Answer 3

All you need is to add those jar on classpath . If you are running the project in eclipse, simply select project properties=>build path=>add jar