Basic use of Java 8 stream stream __java

Use of data flow (stream)
1) Stream's acquisition

① through the collection collection get

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list<integer> list = new Arraylist<integer> (arrays.aslist (1,2,3,4,5));

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stream<integer> stream = List.stream ();

② is obtained by array

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String[] Array = {"Are", "You", "OK"};

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stream<string> stream = Array.stream (Array);

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Handling of primitive type arrays

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Int[] array = {1,2,3,4,5};

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stream<integer> stream = Arrays.stream (array). boxed (); At this point Arrays.stream (array) gets a Intstream object

③ by value (as far as possible using the above 2 ways to get, this way there are defects)

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stream<string> stream = Stream.of ("Are", "You", "OK");

2) Filtering filter

The filter function receives a lambda expression as a parameter that returns a Boolean, in which the stream transports the element to filter one at a time and filters out the element that executes the result to true;

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Filter out non-empty items in a list

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list<string> list = Arrays.aslist ("Are", "You", "", "OK");

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list<string> filted = List.stream ()

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  . Filter (x->!x.empty ())

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  . Collect (Collectors.tolist ());

3) Go to heavy distinct

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list<string> list = Arrays.aslist ("Are", "You", "You", "OK");

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list<string> distincted = List.stream ()

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  . Distinct ()

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  . Collect (Collectors.tolist ());

4) Interception of limit

The first n elements of an intercept stream: