JAVA8 stream接口 distinct，sorted，peek，limit，skip

Dear 丶 2021-09-26 21:46 219阅读 0赞

下面，我们来看其他的剩余的一些中间操作，各自的作用，我也通过注释，做了解析，方法定义如下；

//去重复
    	Stream<T> distinct();
    	//排序
    	Stream<T> sorted();
    	//根据属性排序
    	Stream<T> sorted(Comparator<? super T> comparator);
    	//对对象的进行操作
    	Stream<T> peek(Consumer<? super T> action);
    	//截断--取先maxSize个对象
    	Stream<T> limit(long maxSize);
    	//截断--忽略前N个对象
    	Stream<T> skip(long n);

下面，我们用一些案例，对这些操作，做一些综合的演示

package com.taihao;
    
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.Comparator;
    import java.util.List;
    import java.util.stream.Stream;
    
    public class TestJava8 {
    	public static List<Emp> list = new ArrayList<>();
    	static {
    		list.add(new Emp("xiaoHong1", 20, 1000.0));
    		list.add(new Emp("xiaoHong2", 25, 2000.0));
    		list.add(new Emp("xiaoHong3", 30, 3000.0));
    		list.add(new Emp("xiaoHong4", 35, 4000.0));
    		list.add(new Emp("xiaoHong5", 38, 5000.0));
    		list.add(new Emp("xiaoHong6", 45, 9000.0));
    		list.add(new Emp("xiaoHong7", 55, 10000.0));
    		list.add(new Emp("xiaoHong8", 42, 15000.0));
    	}
    
    	public static void println(Stream<Emp> stream) {
    		stream.forEach(emp -> {
    			System.out.println(String.format("名字：%s，年纪：%s，薪水：%s", emp.getName(), emp.getAge(), emp.getSalary()));
    		});
    	}
    
    	public static void main(String[] args) {
    		// 对数组流，先过滤重复，在排序，再控制台输出 1，2，3
    		Arrays.asList(3, 1, 2, 1).stream().distinct().sorted().forEach(str -> {
    			System.out.println(str);
    		});
    		// 对list里的emp对象，取出薪水，并对薪水进行排序，然后输出薪水的内容，map操作，改变了Strenm的泛型对象
    		list.stream().map(emp -> emp.getSalary()).sorted().forEach(salary -> {
    			System.out.println(salary);
    		});
    		// 根据emp的属性name，进行排序
    		println(list.stream().sorted(Comparator.comparing(Emp::getName)));
    
    		// 给年纪大于30岁的人，薪水提升1.5倍，并输出结果
    		Stream<Emp> stream = list.stream().filter(emp -> {
    			return emp.getAge() > 30;
    		}).peek(emp -> {
    			emp.setSalary(emp.getSalary() * 1.5);
    		});
    		println(stream);
    		// 数字从1开始迭代（无限流），下一个数字，是上个数字+1，忽略前5个 ，并且只取10个数字
    		// 原本1-无限，忽略前5个，就是1-5数字，不要，从6开始，截取10个，就是6-15
    		Stream.iterate(1, x -> ++x).skip(5).limit(10).forEach(System.out::println);
    	}
    
    	public static class Emp {
    		private String name;
    
    		private Integer age;
    
    		private Double salary;
    
    		public Emp(String name, Integer age, Double salary) {
    			super();
    			this.name = name;
    			this.age = age;
    			this.salary = salary;
    		}
    
    		public String getName() {
    			return name;
    		}
    
    		public void setName(String name) {
    			this.name = name;
    		}
    
    		public Integer getAge() {
    			return age;
    		}
    
    		public void setAge(Integer age) {
    			this.age = age;
    		}
    
    		public Double getSalary() {
    			return salary;
    		}
    
    		public void setSalary(Double salary) {
    			this.salary = salary;
    		}
    
    	}
    }

每个例子，也都加了注释，大家看例子，自己get吧

## 1.lambda表达式 ##

[《java8 Lambda表达式简介》][java8 Lambda]

[《java8 lambda表达式，方法的引用以及构造器的引用》][java8 lambda]

### 2.函数式接口 ###

[《java8 函数式接口简介》][java8]

[《JAVA8 Function接口以及同类型的特化的接口》][JAVA8 Function]

[《JAVA8 Consumer接口》][JAVA8 Consumer]

[《JAVA8 Supplier接口》][JAVA8 Supplier]

[《JAVA8 UnaryOperator接口》][JAVA8 UnaryOperator]

[《JAVA8 BiConsumer 接口》][JAVA8 BiConsumer]

3.stream接口操作

[《java8 Stream接口简介》][java8 Stream]

[《 java8 Stream-创建流的几种方式》][java8 Stream-]

[《JAVA8 stream接口 中间操作和终端操作》][JAVA8 stream_]

[《JAVA8 Stream接口，map操作，filter操作，flatMap操作》][JAVA8 Stream_map_filter_flatMap]

[《JAVA8 stream接口 distinct，sorted，peek，limit，skip》][JAVA8 stream_ distinct_sorted_peek_limit_skip]

[《java8 stream接口 终端操作 forEachOrdered和forEach》][java8 stream_ _ forEachOrdered_forEach]

[《java8 stream接口 终端操作 toArray操作》][java8 stream_ _ toArray]

[《java8 stream接口 终端操作 min，max，findFirst，findAny操作》][java8 stream_ _ min_max_findFirst_findAny]

[《java8 stream接口终端操作 count，anyMatch，allMatch，noneMatch》][java8 stream_ count_anyMatch_allMatch_noneMatch]

[《java8 srteam接口终端操作reduce操作》][java8 srteam_reduce]

[《java8 stream接口 终端操作 collect操作》][java8 stream_ _ collect]

4.其他部分

[《java8 Optional静态类简介，以及用法》][java8 Optional]

[java8 Lambda]: https://blog.csdn.net/qq_28410283/article/details/80961022
[java8 lambda]: https://blog.csdn.net/qq_28410283/article/details/80963351
[java8]: https://blog.csdn.net/qq_28410283/article/details/80962325
[JAVA8 Function]: https://blog.csdn.net/qq_28410283/article/details/80615629
[JAVA8 Consumer]: https://blog.csdn.net/qq_28410283/article/details/80618456
[JAVA8 Supplier]: https://blog.csdn.net/qq_28410283/article/details/80625482
[JAVA8 UnaryOperator]: https://blog.csdn.net/qq_28410283/article/details/80634319
[JAVA8 BiConsumer]: https://blog.csdn.net/qq_28410283/article/details/80704487
[java8 Stream]: https://blog.csdn.net/qq_28410283/article/details/80633292
[java8 Stream-]: https://blog.csdn.net/qq_28410283/article/details/80633710
[JAVA8 stream_]: https://blog.csdn.net/qq_28410283/article/details/80634725
[JAVA8 Stream_map_filter_flatMap]: https://blog.csdn.net/qq_28410283/article/details/80642786
[JAVA8 stream_ distinct_sorted_peek_limit_skip]: https://blog.csdn.net/qq_28410283/article/details/80643711
[java8 stream_ _ forEachOrdered_forEach]: https://blog.csdn.net/qq_28410283/article/details/80782808
[java8 stream_ _ toArray]: https://blog.csdn.net/qq_28410283/article/details/80783286
[java8 stream_ _ min_max_findFirst_findAny]: https://blog.csdn.net/qq_28410283/article/details/80783505
[java8 stream_ count_anyMatch_allMatch_noneMatch]: https://blog.csdn.net/qq_28410283/article/details/80783946
[java8 srteam_reduce]: https://blog.csdn.net/qq_28410283/article/details/80873910
[java8 stream_ _ collect]: https://blog.csdn.net/qq_28410283/article/details/81052881
[java8 Optional]: https://blog.csdn.net/qq_28410283/article/details/80952768