19：     class A {
public int getNumber(int a) {
    return a + 1;
}
        }
 
        class B extends A {
public int getNumber (int a) {
return a + 2;
        }
 
public static void main (String args[])  {
A a = new B();
14. System.out.printIn(a.getNumber(0));
15.    }
16. }  
What is the result?
A. Compilation succeeds and 1 is printed.
B. Compilation succeeds and 2 is printed.
C. An error at line 8 causes compilation to fail.
D. An error at line 13 causes compilation to fail.
E. An error at line 14 causes compilation to fail.
Answer：B。记住一句话，成员变量（编译时）看左边，方法（运行时）看右边。