In the NetBeans 8 IDE, by default you get automatic code completion suggestions when typing a dot. You can also trigger the completion manually at any time by pressing CTRL + SPACE.
Pressing that key combination all the time can get annoying quickly though. So here is how to get it on every character you enter (or key you press):
First, go to Tools => Options. Then Select Editor in the top bar, and go to the Code Completion tab. You should now see this menu shown below. Make sure to select your language, in my case Java, in the drop down list:
Then enable the following two checkboxes named Auto Popup on Typing Any Java Identifier Part and Subword completion:
Now you should get auto-completion as visible below:
That’s it, enjoy!