SCJP考试题310-025(第二套<2>)19-50/147

Question No 35
You are assigned the task of building a panel containing a TextArea at the top, a label directly below it,
and a button directly below the label. If the three components are added directly to the panel. Which
layout manager can the panel use to ensure that the TextArea absorbs all of the free vertical space when
the panel is resized?
A. GridLayout.
B. CardLayout.
C. FlowLayout.
D. BorderLayout.
E. GridBagLayout.
Answer: E
Question No 36
Which gets the name of the parent directory file “file.txt”?
A. String name= File.getParentName(“file.txt”);
B. String name= (new File(“file.txt”)).getParent();
C. String name = (new File(“file.txt”)).getParentName();
D. String name= (new File(“file.txt”)).getParentFile();
E. Directory dir=(new File (“file.txt”)).getParentDir();
String name= dir.getName();
Answer: B
Question No 37
Which can be used to encode charS for output?
A. Java.io.OutputStream.
B. Java.io.OutputStreamWriter.
C. Java.io.EncodeOutputStream.
D. Java.io.EncodeWriter.
E. Java.io.BufferedOutputStream.
Answer: B

Question No 38
The file “file.txt” exists on the file system and contsins ASCII text.
Given:
38. try {
39. File f = new File(“file.txt”);
40. OutputStream out = new FileOutputStream(f, true);
41. }
42. catch (IOException) {}
What is the result?
A. The code does not compile.
B. The code runs and no change is made to the file.
C. The code runs and sets the length of the file to 0.
D. An exception is thrown because the file is not closed.
E. The code runs and deletes the file from the file system.
Answer: A
Question No 39
Which constructs a DataOutputStream?
A. New dataOutputStream(“out.txt”);
B. New dataOutputStream(new file(“out.txt”));
C. New dataOutputStream(new writer(“out.txt”));
D. New dataOutputStream(new FileWriter(“out.txt”));
E. New dataOutputStream(new OutputStream(“out.txt”));
F. New dataOutputStream(new FileOutputStream(“out.txt”));
Answer: F
Question No 40
What writes the text “ ” to the end of the file “file.txt”?
A. OutputStream out= new FileOutputStream (“file.txt”);
Out.writeBytes (“ /n”);
B. OutputStream os= new FileOutputStream (“file.txt”, true);
DataOutputStream out = new DataOutputStream(os);
out.writeBytes (“ /n”);
C. OutputStream os= new FileOutputStream (“file.txt”);
DataOutputStream out = new DataOutputStream(os);
out.writeBytes (“ /n”);
D. OutputStream os= new OutputStream (“file.txt”, true);
DataOutputStream out = new DataOutputStream(os);
out.writeBytes (“ /n”);
Answer: B
Question No 41
Given:
1. public class X (
2. public object m () {
3. object o = new float (3.14F);
4. object [] oa = new object [1];
5. oa[0]= o;
6. o = null;
7. return oa[0];
8. }
9. }
When is the float object created in line 3, eligible for garbage collection?
A. Just after line 5
B. Just after line 6
C. Just after line 7 (that is, as the method returns)
D. Never in this method.
Answer: D

Question No 42
Given:
3. string foo = “ABCDE”;
4. foo.substring(3);
5. foo.concat(“XYZ”);
6.
Type the value of foo at line 6.
Answer: ABCDE
Question No 43
Which method is an appropriate way to determine the cosine of 42 degrees?
A. Double d = Math.cos(42);
B. Double d = Math.cosine(42);
C. Double d = Math.cos(Math.toRadians(42));
D. Double d = Math.cos(Math.toDegrees(42));
E. Double d = Math.cosine(Math.toRadians(42));
Answer: C
Question No 44
You need to store elements in a collection that guarantees that no duplicates are stored and all elements
can be accessed in natural order. Which interface provides that capability?
A. Java.util.Map.
B. Java.util.Set.
C. Java.util.List.
D. Java.util.StoredSet.
E. Java.util.StoredMap.
F. Java.util.Collection.
Answer: D
Question No 45
Which statement is true for the class java.util.HashSet?
A. The elements in the collection are ordered.
B. The collection is guaranteed to be immutable.
C. The elements in the collection are guaranteed to be unique.
D. The elements in the collection are accessed using a unique key.
E. The elements in the collections are guaranteed to be synchronized.
Answer: C
Question No 46
Given:
1. public class IfTest (
2. public static void main(string[]args) {
3. int x = 3;
4. int y = 1;
5. if (x = y)
6. system.out.printIn(“Not equal”);
7. else
8. system.out.printIn(“Equal”);
9. }
10. )
What is the result?
A. The output is “Equal”
B. The output in “Not Equal”
C. An error at line 5 causes compilation to fall.
D. The program executes but does not print a message.
Answer: C