本文通过一个Java继承的例子，探讨了在不同子类中重写基类方法的行为。具体展示了当子类覆盖父类方法时，如何确保正确返回当前子类实例的问题。此案例涉及Java面向对象特性，特别是继承和方法覆盖的概念。
Given:
1. class One{
2. public One foo(){return this;}
3. }
4. class Two extends One{
5. public One foo(){return this;}
6. }
7. class Three extends Two{
8. //insert method here
9. }
Which two methods, inserted individually, correctly complete the Three class? (Choose two.)
A. public void foo(){}
B. public int foo(){return 3;}
C. public Two foo(){return this;}
D. public One foo(){return this;}
E. public Object foo(){return this;}
答案：CD
继承题
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