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一.題目
Given:
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| class Cart{ | |
| Product p; | |
| double totalAmount; | |
| } | |
| class Product{ | |
| String name; | |
| Double p; | |
| } | |
| public class OCA_7 { | |
| public static void main(String[] args) { | |
| Cart c = new Cart(); | |
| System.out.println(c.p + ":" + c.totalAmount); | |
| } | |
| } |
What is the result?
A. null:null:0.0
B. null:null
C. <HashCode>:0.0
D. null:0.0
二.答案
D
三.解析
物件的預設值是 null，double的預設值是0.0。
|
型態 |
預設值 |
|
boolean |
false |
|
byte |
0 |
|
int |
0 |
|
long |
0 |
|
double |
0.0 |
|
一般物件型態 |
null |
|
String |
null |
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