In NetBeans 6.7 we can get code completion as we type. Normally we must invoke code completion with Ctrl+Space. To get auto popup code completion we go to Tools | Options | Editor | Code Completion. We select Java from the Language combo box. The option dialog window shows the option Auto Popup on Typing Any Java Identifier Part (What is in a name?). We must select the checkbox to get auto popup code completion.
Now when we write code in the Java editor the code completion popup window shows when we stop typing characters.