Netbeans Java Error: "error: Diamond Operator is not supported in -source 1.5"

Question

I’m trying to use a List of Lists in Java in Netbeans for the first time:

List<List<String>> listao = new ArrayList<>();

But it presents a compilation error on the line where I have the list:

error: Diamond Operator is not supported in -source 1.5

And present the hint:

use -source 7 or Higher to enable Diamond Operator

Okay, but what source is this, and how to do this?

Answer 1

First, right-click on your project to see the drop-down menu of the figure below, where you see the item "Properties" or "Properties":

When opening the properties, change the source code box to JDK 7 or larger: