Given: class ClassA {} class ClassB extends ClassA {} class ClassC extends ClassA {} and: ClassA p0 = new ClassA(); ClassB p1 = new ClassB(); ClassC p2 = new ClassC(); ClassA p3 = new ClassB(); ClassA p4 = new ClassC(); Which three are valid?()
class ClassA {} class ClassB extends ClassA {} class ClassC extends ClassA {} and: ClassA p0 = new ClassA(); ClassB p1 = new ClassB(); ClassC p2 = new ClassC(); ClassA p3 = new ClassB(); ClassA p4 = new ClassC(); Which three are valid?()
类ClassB从ClassA派生,那么ClassA*a=newClassB(…);试问该表达是否合法?为什么?
OLTPON口(CLASSB+)发送光功率不低于()dbm。
ONUPON口(CLASSB+)接受光功率范围为()dbm。
若classB中定义了一个classA的类成员Aa,则关于类成员的正确描述是()
现有: class ClassA {} class ClassB extends ClassA {) class ClassC extends ClassA {) 以及: ClassA p0=new ClassA(); ClassB pl=new ClassB(); ClassC p2=new ClassC(); ClassA p3=new ClassB(); ClassA p4=new ClassC(); 下列哪些是正确的?()