2011年JAVA认证模拟题（13）

会计考友

　Q37. Which of the following are true about IO filters? 　　A Filters are supported on input, but not on output.
　　B Filters are supported by the InputStream/outputStram class hierarchy, but not by the Reader/Writer class hierarchy.
) ]7 V# Y: o% I  u+ A7 x　　C Filters read from one stream and write to another.
　　D A filter may alter data that is read from one stream and written to another.
　　Q38 Which of the following are true?
　　A Only threads have locks.
3 p; t% a4 m, u0 y% d9 y0 e" p　　B Classes have locks
　　C Primitive types have locks.
　　D Only Runnable objects have locks.
　　Q39 What output does the following program display?
　　import java.util.*;
　　class Question {
6 U/ O  e! @# H, F　　public static void main (String args[]) ｝
& E- W0 `! c* A　　String s1 = “abc”;

会计考友

</p>　　String s2 = “def”;
　　Stack stack = new Stack();
　　stack.push(s1);
　　stack.push(s2);
& N$ U, G# ~# G) E: X* S0 f　　try {
　　String s3 = (String) stack.pop() +
. p" w1 `/ v8 ^* g: t/ y! G　　(String)stack.pop();
4 m  }  ~- E5 m! Z　　System.out.println(s3);
　　｝ catch(EmptyStackException ex) {
; V* A1 J: V8 c# U5 v　　｝
　　｝
　　｝
( v6 i( w# N, [　　A abcdef
3 s0 j2 a9 t7 F! G+ h* A' I　　B defabc
2 l$ D, h7 u& w　　C abcabc
　　D defdef
4 d$ e0 i! @3 W( M) `% A6 K　　Q037 CD
　　Q038 B
8 O8 r6 I% Y1 m) B9 u; z1 A$ I% w　　Q039 B