Lambda != method reference
Most of the IDE’s give you hints, that you could replace lambdas with method references. But there is a subtle difference between them.
I was refactoring commit at work on Vaadin application. To improve readability I started replacing lambdas with method references. After refactoring, and testing I noticed, that button click action resulted in NullPointerException.
In this example, I’ll try to show the difference between lambda expression and method reference.
My cool function invoked
An object must be initialized before using method reference operator on it.
Lambdas are bit different, they can access a variable from outside their scope.