public class TestStreamAPI1 {
List<Employee> emps = Arrays.asList(
new Employee(102, "李四", 59, 6666.66),
new Employee(101, "張三", 18, 9999.99),
new Employee(103, "王五", 28, 3333.33),
new Employee(104, "趙六", 8, 7777.77),
new Employee(104, "趙六", 8, 7777.77),
new Employee(104, "趙六", 8, 7777.77),
new Employee(105, "田七", 38, 5555.55)
);
//2. 中間操作
/*
映射
map——接收 Lambda , 將元素轉(zhuǎn)換成其他形式或提取信息。接收一個(gè)函數(shù)作為參數(shù),該函數(shù)會(huì)被應(yīng)用到每個(gè)元素上,并將其映射成一個(gè)新的元素。
flatMap——接收一個(gè)函數(shù)作為參數(shù),將流中的每個(gè)值都換成另一個(gè)流,然后把所有流連接成一個(gè)流
*/
@Test
public void test1(){
Stream<String> str = emps.stream()
.map((e) -> e.getName());
System.out.println("-------------------------------------------");
List<String> strList = Arrays.asList("aaa", "bbb", "ccc", "ddd", "eee");
Stream<String> stream = strList.stream()
.map(String::toUpperCase);
stream.forEach(System.out::println);
Stream<Stream<Character>> stream2 = strList.stream()
.map(TestStreamAPI1::filterCharacter);
stream2.forEach((sm) -> {
sm.forEach(System.out::println);
});
System.out.println("---------------------------------------------");
Stream<Character> stream3 = strList.stream()
.flatMap(TestStreamAPI1::filterCharacter);
stream3.forEach(System.out::println);
}
public static Stream<Character> filterCharacter(String str){
List<Character> list = new ArrayList<>();
for (Character ch : str.toCharArray()) {
list.add(ch);
}
return list.stream();
}
/*
sorted()——自然排序
sorted(Comparator com)——定制排序
*/
@Test
public void test2(){
emps.stream()
.map(Employee::getName)
.sorted()
.forEach(System.out::println);
System.out.println("------------------------------------");
emps.stream()
.sorted((x, y) -> {
if(x.getAge() == y.getAge()){
return x.getName().compareTo(y.getName());
}else{
return Integer.compare(x.getAge(), y.getAge());
}
}).forEach(System.out::println);
}