All language subtitles for 009 Stream Pipeline – Part 2_en

The Stream pipeline replaces Lupe's.

Once again, you will run an array less through a stream pipeline.

Remember that loops can get messy using loops, simple operations on an array list can get really tedious,

but Java offers a cleaner way.

First, you're going to learn about the intermediate operation map, what map does is it updates every

single element in the sequence.

It uses a lambda expression that receives each element.

And returns the updated elements.

Mapped out, Java starts with an array list of four prices.

With tax has the following reference.

The function receives the reference as a parameter, both the parameter and outside variable share a

reference to the same array list.

And so here we're updating elements in the Israelis to include taxes.

Once again, loops are messy and it's easier to run the original list through a stream pipeline.

Were each operation in the pipeline updates the sequence of elements in some way the pipeline is going

to have one intermediate operation map which like filter goes through every element in the sequence,

and map expects us to return the updated elements.

We can use the arrow key that points to the code we're going to write and here will return the updated

value.

That same element times one point one three.

OK, we're going to end the pipeline with the terminal operation collects.

Collect except a collector, which is going to collect the updated sequence of elements and return it

as a list.

You can't store a list of elements in a variable of type array list, but we can add all of the elements

from the list that's being returned by the pipeline.

Let's run this code.

And perfect, once again, running the rails through a pipeline is a lot cleaner than using a loop.

We can clean it up even more, because if you only have one line, the arrow, he can point directly

to the value that we're returning.

You can run to make sure.

And everything works.

All right, finally, you can chain intermediate operations.

In this class, first we filter the lower prices.

Then we update every element in the filtered array list.

OK, I'm going to give you the chance to pause the video and try to work this one out yourself.

OK, so first we're going to filter elements with a price less than five dollars.

The updated sequence continues through the pipeline and the next operation in the pipeline is going

to be map, then we can use map to update every single element from the filtered sequence map receives

each price and returns the updated price.

We're going to end the pipeline with the terminal operation, collect, collect, accepts a collector,

and from the series of collectors, we're going to choose the collector to list, which is going to

accumulate every single element and aggregate it into a list.

And remember, you can't store a list of elements in a variable of type array list, but we can add

all of the elements from the list that's being returned by the pipeline.

First, we're filtering oil price values below five dollars, and then we're updating every element

in that filter sequence.

And we get the expected results.

Let's recap in this lesson, you chained to intermediate operations, the filter operation filters elements

based on a predicate.

The map operation updates every elements.

And finally, a terminal operation ends the pipeline by returning the results.