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 … Read more
You need to enable the option Project Properties -> Build -> Packaging -> Build JAR after compiling (but this is enabled by default)
Quick solution in NetBeans 6.8. In the Projects window right-click on the name of the project that lacks library -> Properties -> The Project Properties window opens. In Categories tree select “Libraries” node -> On the right side of the Project Properties window press button “Add JAR/Folder” -> Select jars you need. You also can … Read more
Since you make sure to put your instances.add(this) at the end of the constructor you should IMHO be safe to tell the compiler to simply suppress the warning (*). A warning, by its nature, doesn’t necessarily mean that there’s something wrong, it just requires your attention. If you know what you’re doing you can use … Read more