途中、感受

Local 日期時間類

LocalDate localDate = LocalDate.now();
LocalTime localTime = LocalTime.now();
LocalDateTime localDateTime = LocalDateTime.now();
System.out.println(localDate);
System.out.println(localTime);
System.out.println(localDateTime);
Instant instant = Instant.now();
OffsetDateTime offsetDateTime = instant.atOffset(ZoneOffset.ofHours(8));
System.out.println(instant);
System.out.println(offsetDateTime);

Lambda表達式

Comparator<Integer> com1 = new Comparator<Integer>() {
    @Override
    public int compare(Integer o1, Integer o2) {
      return Integer.compare(o1, o2);
    }
};
System.out.println(com1.compare(12,13));

System.out.println("===========");
// Lambda 表達式
Comparator<Integer> com2 = (o1, o2) -> Integer.compare(o1, o2);
System.out.println(com2.compare(12,13));

List<String> stringList = new ArrayList<>();
stringList.removeIf(str-> str.contains("aaa")); // 刪除List中包含aaa的

// 方法引用
Comparator<Integer> com3 = Integer::compare;
System.out.println(com3.compare(12,13));

方法引用
類（或?qū)ο螅?: 方法名
對象 :: 非靜態(tài)方法
類 :: 靜態(tài)方法
類 :: 非靜態(tài)方法

Consumer<String> con1 = str -> System.out.println(str);
con1.accept("北京");

Consumer<String> con2 = System.out::println;
con2.accept("北京");

Person person = new Person("張三", "23");
Supplier<String> supplier = () -> person.getName();
System.out.println(supplier.get());

Supplier<String> supplier1 = person::getName;
Function<Person, String> func3 = Person::getName;
System.out.println(supplier1.get());

Function<Double, Long> func = (o) -> Math.round(o);
func.apply(1.11);

Function<Double, Long> func1 = Math::round;
func1.apply(1.12);

Supplier<Person> func4 = () -> new Person();
Supplier<Person> func5 = Person::new; // new Person()

BiFunction<String, String, Person> fun6 = Person::new; // new Person(String name, String age)

Function<Integer, String[]> fun7 = String[]::new; // new String[Integer length]