單項(xiàng)選擇題

1. class A { 
2. public int getNumber（int a） { 
3.     return a + 1； 
4. } 
5. } 
6.   
7. class B extends A { 
8. public int getNumber （int a） { 
9. return a + 2 
10. } 
11.   
12. public static void main （String args[]）  { 
13. 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.

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單項(xiàng)選擇題

public class X implements Runnable （ 
private int x； 
private int y；
 public static void main（String [] args） （ 
X that = new X（）； 
（new Thread（that）） . start（ ）； 
（new Thread（that）） . start（ ）； 
） 
public synchronized void run（ ） （ 
for （；；） （ 
 x++； 
y++； 
System.out.printIn（“x = “ +  x  + “， y = “ + y）； 
） 
） 
）  
What is the result？（）  

A. An error at line 11 causes compilation to fail.
B. Errors at lines 7 and 8 cause compilation to fail.
C. The program prints pairs of values for x and y that might not always be the same on the same line （for example， “x=2， y=1”）
D. The program prints pairs of values for x and y that are always the same on the same line （for example， “x=1， y=1”. In addition， each value appears twice （for example， “x=1， y=1” followed by “x=1， y=1”）
E. The program prints pairs of values for x and y that are always the same on the same line （for example， “x=1， y=1”. In addition， each value appears twice （for example， “x=1， y=1” followed by “x=2s， y=2”）
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