第94題

Given:
11. public class Rainbow {
12. public enum MyColor {
13. RED(0xff0000), GREEN(0x00ff00), BLUE(0x0000ff);
14. private final int rgb;
15. MyColor(int rgb){this.rgb = rgb;}
16. public int getRGB(){return rgb;}
17. }
18. public static void main(String[] args){
19. //insert code here
20. }
21. }
Which code fragment inserted at line 19, allows the Rainbow class to compile?
A. MyColor skyColor = BLUE;
B. MyColor treeColor = MyColor.GREEN;
C. if(RED.getRGB() < BLUE.getRGB()){}
D. Compilation fails due to other error(s) in the code.
E. MyColor purple = new MyColor(0xff00ff);
F. MyColor purple = MyColor.BLUE + MyColor.RED;
答案：B
參考：8-5 內部類別、8-6 Java列舉類型
-------------------------------------------------------------------

A. MyColor skyColor = BLUE; //MyColor skyColor = MyColor.BLUE;
C. if(RED.getRGB() < BLUE.getRGB()){} //不可以直接用比較運算
D. Compilation fails due to other error(s) in the code. //不會編譯失敗
E. MyColor purple = new MyColor(0xff00ff); //類舉類型不可以實體化
F. MyColor purple = MyColor.BLUE + MyColor.RED; //類舉類型不可以用在加法運用上