第9天第2节: 两个重要比较

1. overloading vs overriding

Definition:

    overloading: same method name, different number of argument or argument type. no permission limitation

    overriding:   same method name, number of argument and argument type. private<default<public

Usage:

    overloading; within a class

    overriding: in a class inheritance

2. this vs super

    .member or .method

           this: looking in current class first, then looking in parent class if not found in current class

           super: looking in the parent class

    this() or supper() used in the constructor

           this(): call constructor of current class, put at the first line

           supper(): call constructor of parent class, put at the first line

    refer to a object ( passed in as argument)

           this: means current object

           supper: no such concept