cs2030s-midterms-cheatsheet.pdf
S <: T
(S 是 T 的子类型)S <: T
且 T <: U
⇒ S <: U
C(S) <: C(T)
(若 S <: T
,且 C
协变)C(T) <: C(S)
(若 S <: T
,且 C
逆变)class C implements A, B
(类实现多个接口)interface I extends A, B
(接口继承多个接口)final
类不可被继承(如 final class Circle
)List<? extends T>
(协变,允许读取)List<? super T>
(逆变,允许写入)A.<String>contains(strArr, "hello")
T[] arr = (T[]) new Object[size]
)class Pair<S extends Comparable<S>, T>
(类型参数边界)class A extends B implements Comparable<A>
异常类型
IllegalArgumentException
(参数不合法)class MyException extends IllegalArgumentException
异常处理结构
try {
// 可能抛出异常的代码
} catch (IllegalArgumentException e) {
// 处理特定异常
} finally {
// 始终执行
}
throws
声明:public Circle(Point c, double r) throws IllegalArgumentException
@FunctionalInterface
标记(如 Transformer<T, R>
)Transformer<Integer, Integer> square = x -> x * x;
A::foo
(静态方法)或 aInstance::bar
(实例方法)柯里化(Currying):x -> y -> x + y
map
与 flatMap
:
list.map(x -> x + 1).flatMap(x -> List.of(x, x * 2));