Java8新特性_创建 Stream

 

package com.zs.boot.controller;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.stream.Stream;

import org.junit.Test;

/*
 * 一、Stream API 的操作步骤：
 * 
 * 1. 创建 Stream
 * 
 * 2. 中间操作
 * 
 * 3. 终止操作(终端操作)
 */
public class TestStreamaAPI {
	
	//1. 创建 Stream
	@Test
	public void test1(){
		//1. Collection 提供了两个方法  stream() 与 parallelStream()
		List<String> list = new ArrayList<>();
		Stream<String> stream = list.stream(); //获取一个顺序流
		Stream<String> parallelStream = list.parallelStream(); //获取一个并行流
		
		//2. 通过 Arrays 中的 stream() 获取一个数组流
		Integer[] nums = new Integer[10];
		Stream<Integer> stream1 = Arrays.stream(nums);

		Employee[] emps = new Employee[10];
		Stream<Employee> stream11 = Arrays.stream(emps);
		
		//3. 通过 Stream 类中静态方法 of()
		Stream<Integer> stream2 = Stream.of(1,2,3,4,5,6);

		Stream<String> stream22 = Stream.of("aa","bb","cc");
		
		//4. 创建无限流
		//方法1：迭代
		Stream<Integer> stream3 = Stream.iterate(0, (x) -> x + 2).limit(10);
		stream3.forEach(System.out::println);
		
		//方法2：生成
		Stream<Double> stream4 = Stream.generate(Math::random).limit(2);
		stream4.forEach(System.out::println);
		
	}
	



	public class Employee {

		private int id;
		private String name;
		private int age;
		private double salary;

		public Employee() {
		}

		public Employee(String name) {
			this.name = name;
		}

		public Employee(String name, int age) {
			this.name = name;
			this.age = age;
		}

		public Employee(int id, String name, int age, double salary) {
			this.id = id;
			this.name = name;
			this.age = age;
			this.salary = salary;
		}

		public int getId() {
			return id;
		}

		public void setId(int id) {
			this.id = id;
		}

		public String getName() {
			return name;
		}

		public void setName(String name) {
			this.name = name;
		}

		public int getAge() {
			return age;
		}

		public void setAge(int age) {
			this.age = age;
		}

		public double getSalary() {
			return salary;
		}

		public void setSalary(double salary) {
			this.salary = salary;
		}

		public String show() {
			return "测试方法引用！";
		}

		@Override
		public int hashCode() {
			final int prime = 31;
			int result = 1;
			result = prime * result + age;
			result = prime * result + id;
			result = prime * result + ((name == null) ? 0 : name.hashCode());
			long temp;
			temp = Double.doubleToLongBits(salary);
			result = prime * result + (int) (temp ^ (temp >>> 32));
			return result;
		}

		@Override
		public boolean equals(Object obj) {
			if (this == obj)
				return true;
			if (obj == null)
				return false;
			if (getClass() != obj.getClass())
				return false;
			Employee other = (Employee) obj;
			if (age != other.age)
				return false;
			if (id != other.id)
				return false;
			if (name == null) {
				if (other.name != null)
					return false;
			} else if (!name.equals(other.name))
				return false;
			if (Double.doubleToLongBits(salary) != Double.doubleToLongBits(other.salary))
				return false;
			return true;
		}

		@Override
		public String toString() {
			return "Employee [id=" + id + ", name=" + name + ", age=" + age + ", salary=" + salary + "]";
		}

	}

}