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🍱 add stream example
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‎java8-stream/README.md‎

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# Stream
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## 中间操作
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| 操作 | 类型 | 返回类型 | 操作参数 | 函数描述符 |
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|:-----:|:--------|:-------|:-------|:-------|
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| `filter` | 中间 | `Stream<T>` | `Predicate<T>` | `T -> boolean` |
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| `map` | 中间 | `Stream<R>` | `Function<T, R>` | `T -> R` |
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| `limit` | 中间 | `Stream<T>` | | |
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| `sorted` | 中间 | `Stream<T>` | `Comparator<T>` | `(T, T) -> int` |
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| `distinct` | 中间 | `Stream<T>` | | |
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## 收集操作（终端操作）
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| 操作 | 类型 | 目的 |
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|:-----:|:--------|:-------|
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| `forEach` | 收集 | 消费流中的每个元素并对其应用 Lambda。这一操作返回 void |
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| `count` | 收集 | 返回流中元素的个数。这一操作返回 long |
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| `collect` | 收集 | 把流归约成一个集合，比如 List、Map 甚至是 Integer。 |

‎java8-stream/src/main/java/io/github/biezhi/java8/stream/Project.java‎

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package io.github.biezhi.java8.stream;
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import lombok.Builder;
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import lombok.Data;
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/**
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* 项目
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*
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* @author biezhi
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* @date 2018/2/9
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*/
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@Data
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@Builder
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public class Project {
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/**
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* 项目名称
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*/
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private String name;
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/**
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* 编程语言
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*/
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private String language;
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/**
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* star 数
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*/
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private Integer stars;
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/**
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* 描述
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*/
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private String description;
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/**
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* 作者
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*/
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private String author;
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}

‎java8-stream/src/main/java/io/github/biezhi/java8/stream/lesson1/Java7.java‎

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package io.github.biezhi.java8.stream.lesson1;
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import io.github.biezhi.java8.stream.Project;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.Comparator;
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import java.util.List;
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/**
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* @author biezhi
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* @date 2018/2/11
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*/
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public class Java7 {
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public static void main(String[] args) {
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List<Project> result = new ArrayList<>();
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List<Project> projects = new ArrayList<>();
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for (Project project : projects) {
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if(project.getStars() > 1000){
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result.add(project);
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}
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}
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Collections.sort(projects, new Comparator<Project>() {
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@Override
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public int compare(Project o1, Project o2) {
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return o1.getStars().compareTo(o2.getStars());
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}
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});
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List<String> names = new ArrayList<>();
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for (Project project : projects) {
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names.add(project.getName());
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}
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}
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}

‎java8-stream/src/main/java/io/github/biezhi/java8/stream/lesson1/Java8.java‎

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package io.github.biezhi.java8.stream.lesson1;
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import io.github.biezhi.java8.stream.Project;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.Comparator;
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import java.util.List;
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import java.util.stream.Collectors;
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/**
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* @author biezhi
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* @date 2018/2/11
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*/
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public class Java8 {
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public static void main(String[] args) {
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List<Project> result = new ArrayList<>();
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List<Project> projects = new ArrayList<>();
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List<String> names = projects.stream()
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.filter(p -> p.getStars() > 1000)
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.map(Project::getName)
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.limit(3)
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.collect(Collectors.toList());
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System.out.println(names);
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}
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}

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