How to check the execution environment being used in Eclipse?

I want to import the package java.util.concurrent in my Java project, b开发者_如何学Gout it is not available. This project is developed in Eclipse, and my Eclipse is using JRE6. java.util.concurrent package is available since Java 1.5, and how come JRE6 does not contain Java 1.5?

My only guess is that Eclipse is currently using an execution environment that is older than Java 1.5, but how can I verify that?

Or, is there any other way to import a package that is not shown in the drop down selection box?

Thanks in advance.

Right click on the project

Properties -> Java Built Path -> Libraries ->Check the JRE/JDK is at least 1.5

Properties ->Java Compiler -> check if the Compiler is at least 1.5

Help->About->Installation Details->Configuration. You can also try setting the VM path dirrectly in ecipse.ini.

-vm {$path_to_jdk$}/jdk1.6.0_18/bin