Lambda表达式中针对List的常用方法

ZChao_Smile

于 2019-03-14 17:25:39 发布

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分类专栏： JAVA 文章标签： Lambda

本文链接：https://blog.youkuaiyun.com/richangbiji/article/details/88557291

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本文详细介绍了如何使用Java的Stream API进行集合操作，包括转换List为Map、按名称分组、以及按照不同条件进行排序。通过具体的代码示例，展示了如何创建Person对象列表，并运用Stream API实现数据的高效处理。

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准备工作：


public class People
{
	public People(int age, String name, boolean sex, int weight, int height)
	{
		super();
		this.age = age;
		this.name = name;
		this.sex = sex;
		this.weight = weight;
		this.height = height;
	}
	public People()
	{
		super();
	}
	private int age;
	
	private String name;
	
	private boolean sex;
	
	private int weight;
	
	private int height;
	......
}

List<People> list1 = new ArrayList<>();
list1.add(new People(12, "ZS", true, 100, 160));
list1.add(new People(10, "LS", false, 110, 150));
list1.add(new People(10, "WW", true, 100, 170));

List =>Map

Map<String, People> map = list1.stream().collect(Collectors.toMap(People::getName, people -> people));

List 分组

Map<String, List<People>> mapList = list1.stream().collect(Collectors.groupingBy(People::getName));

List 排序 – 从低到高

list1.sort((p1, p2) -> p1.getAge() - p2.getAge());

List 多条件排序 – 先按照年龄，再按照身高

list1.sort(Comparator.comparing(People::getAge).thenComparing(People::getHeight));