- In the Project tab, right-click on the project and select Properties. In the Library category select Java Platform JDK 1.6.
- Then, in the Source category select Source/Binary Format JDK6.
- This assumes that you installed JDK 1.6 and NetBeans knows about
this. - JDK 1.6 must be known to NetBeans as a Java Platform.
- From the menu select menu Tools → Java Platform Manager.
- If JDK 1.6 is not in the list, you can add it there.