JAVA - 【Stream】List流操作

目錄

• 流遍歷 forEach ( Consumer<? super T> action )
• 流過濾 filter
• 流排序 sorted
• 流匹配
  • anyMatch
  • allMatch
  • noneMatch
• 流計數 count
• 流規約 reduce
• 流映射 map ( Consumer<? super T> action )
• 並行流操作 parallelStream

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1> 流過濾

stringCollection
	.stream()
	.filter((s) -> s.startsWith("a"))
	.forEach(list1::add);

2> 流排序

stringCollection
	.stream()
	.sorted()
	.forEach(list2::add);

3> 流匹配

boolean flag1 = 
	stringCollection
	.stream()
	.sorted()
	.anyMatch(a->a.startsWith("a"));
boolean flag2 = 
	stringCollection
	.stream()
	.sorted()
	.anyMatch(a->a.startsWith("a"));
boolean flag3 = 
	stringCollection
	.stream()
	.sorted()
	.anyMatch(a->a.startsWith("a"));

4> 流規約

Optional<Integer> res = 
		list
		.stream()
		.reduce((a,b)->a+b);
	//res.ifPresent(System.out::println);
	int result = res.get();


Optional<String> temp_res = stringCollection
	.stream()
	.reduce((a,b)->a+","+b);
String res = "["+temp_res.get()+"]";
System.out.println(res);

5> 流映射

stringCollection
	.stream()
	.map(String::toLowerCase)
	.forEach(list3::add);

6> 並行流操作

☞ 使用parallelStream()替換stream()即可。