Q61 Suppose that classes X and Y are subclasses of Z and Z implements the W interface. Which of the following are true? A A reference to an object of class X can be cast to a reference to an object of class Y. ^: X/ O+ E9 K. e+ `" Q B A reference to an object of class Y can be cast to a reference to an object of class X.: ^# s+ D: s# u6 N
C A reference to an object of class X can be cast to a reference to an object of class Z.. [: W0 q2 ?8 H. y( q& W
D A reference to an object of class Y can be cast to a reference to an object of class Z.& t5 ?: `' G2 D) S2 _2 g( E" |
E A reference to an object of class X can be cast to a reference to an object of interface W.- N( }6 I, v3 D r
F A reference to an object of class Y can be cast to a reference to an object of interface W. 6 V( G4 X% f: Q2 z. _( W/ d; p G A reference to an object of class Z can be cast to a reference to an object of interface W.4 R- O0 t& J j
Q62 Which of the following are characteristic of a fully encapsulated class? F3 t; [& V1 e( F A All variables are private. & X2 R# D5 B# o% D, [) ]& v B All methods are private.
</p> C Methods are provided to access the class’s properties.% _9 f* r- A1 C+ s" n# ~
D The class’s design may be changed with minimal impact on its implementation. 5 k' F" } _! \4 m) l Q63. What output is displayed as the result of executing the following statement?6 U9 F& x6 W/ H- k4 i
System.out.println( “ // Looks like a* w% M2 b; u/ C1 c& K( X. o$ w! V
comment.”);5 n3 Z1 H6 Y# P9 A3 B/ i- d
A // Looks like a comment. w+ n+ H2 O; V# G, B
B / Looks like a comment. ; \4 d% ?5 I- n! v1 E1 g C No output is displayed.+ K% ^7 `- m( ]3 p7 N8 q
D The statement results in a compilation error.- G+ Y2 a( H9 V: B A
Q061 CDEFG , b2 Y2 _5 P' n Q062 AC6 b- s. _+ U) @" `
Q063 A
发表于 2012-8-4 12:33:16
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