Simple use of stream in Java

In Java8, there is the concept of stream flow. I personally think that the use of streams can help us better iterate over the collection of data.

Let's take a look at the code for the normal for loop and stream stream.

public static void Main (string[] args) {        //Remove even        list<integer> List = arrays.aslist (1,2,3,4);        1.for loop        list<integer> newList1 = new arraylist<> ();        For (integer integer:list) {            if (integer% 2 = = 0) {                newlist1.add (integer);}        }        System.out.println (newList1);        2.stream stream        list<integer> newList2 = List.stream (). filter (x, x 2 = = 0). Collect (Collectors.tolist ()); C12/>system.out.println (NEWLIST2);    }

Output Result:

[2, 4][2, 4]

As you can see, the use of stream streams can sometimes simplify the accountability of our code, and with lambda expressions, you can make your code easier to understand.

Here's a brief introduction to the use of stream streams in Java:

1. Create Stream stream

List collection Creation Create: Call list's Stream method, such as List.stream ()

The array is created by passing in the array via Arrays.stream (), such as: Arrays.stream (new integer[]{1,2})

Note: Stream streams are created and can only be used once, and need to be created again if you want to cycle again!

2. Introduction of common methods:

The flow method is divided into intermediate operations and terminal operations, as the name implies, intermediate operation refers to the call method after the generation of a new stream, you can continue to perform operations, and terminal operations is the end of the use of the stream.

Intermediate Operation:

1.filter filter out non-conforming data

2.limit takes only the first X data

3.skip Skip (delete) x data

4.distinct to duplicate data

5.sorted sorting

6.map to data reorganization, generate new data stream (how to remove user age from user collection stream as new stream)

Terminal operation:

1.count Statistical Data Quantity

2.forEach each data in the stream executes the incoming method

3.anyMatch at least one match, return bool

4.allMatch matches all, returns bool

5.collect can pass in a common method in the collection, for example: Collector.tolist () flows back to the collection, Collector.groupingby () groups the data in the stream

6.reduce perform a return operation, such as summation, etc.

Let's start with a simple introduction to stream streaming in Java, thank you.

Simple use of stream in Java