SCJP考试题310-025(第二套<3>)51-91/147

这是第2套题中的51-90题
310-025
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Question No 51
Exhibit:
1. import java.io.IOException;
2. public class ExceptionTest(
3. public static void main (String[]args)
4. try (
5. methodA();
6. ) catch (IOException e) (
7. system.out.printIn(“Caught IOException”);
8. ) catch (Exception e) (
9. system.out.printIn(“Caught Exception”);
10. )
11. )
12. public void methodA () {
13. throw new IOException ();
14. )
15. )
What is the result?
A. The code will not compile.
B. The output is caught exception.
C. The output is caught IOException.
D. The program executes normally without printing a message.
Answer: A
Question No 52
Exhibit:
1. public class test {
2. public static string output = “”
3.
4. public static void foo(int i) {
5. try {
6. if(i= =1) {
7. throw new Exception ();
8. }
9. output += “1”;
10. )
11. catch(Exception e) {
12. output += “2”;
13. return;
14. )
15. finally (
16. output += “3”;
17. )
18. output += “4”;
19. )
20.
21. public static void main (string args[]) (
22. foo(0);
23. foo(1);
24.
25. )
26. )
What is the value of the variable output at line 24?
Answer: 13423
Question No 53
Given:
1. public class Foo implements Runnable (
2. public void run (Thread t) {
3. system.out.printIn(“Running.”);
4. }
5. public static void main (String[] args) {
6. new thread (new Foo()).start();
7. )
8. )
What is the result?
A. An exception is thrown.
B. The program exists without printing anything.
C. An error at line 1 causes compilation to fail.
D. An error at line 2 causes the compilation to fail.
E. “Running” is printed and the program exits.
Answer: D
Question No 54
Which statement is true?
A. If only one thread is blocked in the wait method of an object, and another thread executes the
modify on that same object, then the first thread immediately resumes execution.
B. If a thread is blocked in the wait method of an object, and another thread executes the notify
method on the same object, it is still possible that the first thread might never resume execution.
C. If a thread is blocked in the wait method of an object, and another thread executes the notify
method on the same object, then the first thread definitely resumes execution as a direct and sole
consequence of the notify call.
D. If two threads are blocked in the wait method of one object, and another thread executes the notify
method on the same object, then the first thread that executed the wait call first definitely resumes
execution as a direct and sole consequence of the notify call.
Answer: B
Question No 55
Which two CANNOT directly cause a thread to stop executing? (Choose Two)
A. Calling the yield method.
B. Calling the wait method on an object.
C. Calling the notify method on an object.
D. Calling the notifyAll method on an object.
E. Calling the start method on another Thread object.
Answer: C, D
Question No 56
Which two can be used to create a new Thread? (Choose Two)
A. Extend java.lang.Thread and override the run method.
B. Extend java.lang.Runnable and override the start method.
C. Implement java.lang.thread and implement the run method.
D. Implement java.lang.Runnable and implement the run method.
E. Implement java.lang.Thread and implement the start method.
Answer: A, D
转

Question No 54
Which statement is true?
A. If only one thread is blocked in the wait method of an object, and another thread executes the
modify on that same object, then the first thread immediately resumes execution.
B. If a thread is blocked in the wait method of an object, and another thread executes the notify
method on the same object, it is still possible that the first thread might never resume execution.
C. If a thread is blocked in the wait method of an object, and another thread executes the notify
method on the same object, then the first thread definitely resumes execution as a direct and sole
consequence of the notify call.
D. If two threads are blocked in the wait method of one object, and another thread executes the notify
method on the same object, then the first thread that executed the wait call first definitely resumes
execution as a direct and sole consequence of the notify call.
Answer: B
Question No 55
Which two CANNOT directly cause a thread to stop executing? (Choose Two)
A. Calling the yield method.
B. Calling the wait method on an object.
C. Calling the notify method on an object.
D. Calling the notifyAll method on an object.
E. Calling the start method on another Thread object.
Answer: C, D
Question No 56
Which two can be used to create a new Thread? (Choose Two)
A. Extend java.lang.Thread and override the run method.
B. Extend java.lang.Runnable and override the start method.
C. Implement java.lang.thread and implement the run method.
D. Implement java.lang.Runnable and implement the run method.
E. Implement java.lang.Thread and implement the start method.
Answer: A, D

Question No 57
Given:
1. public class SyncTest (
2. private int x;
3. private int y;
4. private synchronized void setX (int i) (x=1;)
5. private synchronized void setY (int i) (y=1;)
6. public void setXY(int 1)(set X(i); setY(i);)
7. public synchronized Boolean check() (return x !=y;)
8. )
Under which conditions will check () return true when called from a different class?
A. Check() can never return true.
B. Check() can return true when setXY is called by multiple threads.
C. Check() can return true when multiple threads call setX and setY separately.
D. Check() can only return true if SyncTest is changed to allow x and y to be set separately.
Answer: B
Question No 58
Exhibit:
1. class A implements runable (
2. int i;
3. public void run () (
4. try (
5. thread.sleep(5000);
6. i= 10;
7. ) catch(InterruptedException e) {}
8. )
9. )
10.
11. public class Test {
12. public static void main (string args[]) (
13. try (
14. A a = new A ();
15. Thread t = new Thread (a);
16. t.start();
17.
18. int j= a.i;
19.
20. ) catch (Exception e) {}
21. )
22. )
Which statement al line 17 will ensure that j=10 at line 19?
A. a.wait();
B. t.wait();
C. t.join();
D. t.yield();
E. t.notify();
F. a.notify();
G. t.interrupt();
Answer: C
Question No 59
Exhibit:
1. public class X implements Runnable (
2. private int x;
3. private int y;
4.
5. public static void main(String [] args) (
6. X that = new X();
7. (new Thread(that)) . start( );
8. (new Thread(that)) . start( );
9. )
10.
11. public synchronized void run( ) (
12. for (;;) (
13. x++;
14. y++;
15. System.out.printIn(“x = “ + x + “, y = “ + y);
16. )
17. )
18. )
What is the result?
A. An error at line 11 causes compilation to fail.
B. Errors at lines 7 and 8 cause compilation to fail.
C. The program prints pairs of values for x and y that might not always be the same on the same line
(for example, “x=2, y=1”)
D. The program prints pairs of values for x and y that are always the same on the same line (for
example, “x=1, y=1”. In addition, each value appears twice (for example, “x=1, y=1” followed by
“x=1, y=1”)
E. The program prints pairs of values for x and y that are always the same on the same line (for
example, “x=1, y=1”. In addition, each value appears twice (for example, “x=1, y=1” followed by
“x=2s, y=2”)
Answer: E
QUESTION NO: 60
Which two CANNOT directly cause a thread to stop executing? (Choose Two)
A. Existing from a synchronized block.
B. Calling the wait method on an object.
C. Calling notify method on an object.
D. Calling read method on an InputStream object.
E. Calling the SetPriority method on a Thread object.
Answer: A, C 转

QUESTION NO: 61
Exhibit
1. public class SyncTest{
2. public static void main(String[] args) {
3. final StringBuffer s1= new StringBuffer();
4. final StringBuffer s2= new StringBuffer();
5. new Thread () {
6. public void run() {
7. synchronized(s1) {
8. s2.append(“A”);
9. synchronized(s2) {
10. s2.append(“B”);
11. System.out.print(s1);
12. System.out.print(s2);
13. }
14. }
15. }
16. }.start();
17. new Thread() {
18. public void run() {
19. synchronized(s2) {
20. s2.append(“C”);
21. synchronized(s1) {
22. s1.append(“D”);
23. System.out.print(s2);
24. System.out.print(s1);
25. }
26. }
27. }
28. }.start();
29. }
30. }
Which two statements are true? (Choose Two)
A. The program prints “ABBCAD”
B. The program prints “CDDACB”
C. The program prints “ADCBADBC”
D. The output is a non-deterministic point because of a possible deadlock condition.
E. The output is dependent on the threading model of the system the program is running on.
Answer: D, B
QUESTION NO: 62
Which method in the Thread class is used to create and launch a new thread of execution?
A. Run();
B. Start();
B. Execute();
C. Run(Runnable r);
D. Start(Runnable r);
E. Execute(Thread t);
Answer: B
-
QUESTION NO: 63
Given:
5. String foo = “base”;
6. foo.substring(0,3);
7. foo.concat(“ket”)
8.
Type the value of foo at line 8.
Answer: BASE
QUESTION NO: 64
Which code determines the int value foo closest to, but not greater than, a double value bar?
A. Int foo = (int) Math.max(bar);
B. Int foo = (int) Math.min(bar);
C. Int foo = (int) Math.abs(bar);
D. Int foo = (int) Math.ceil(bar);
E. Int foo = (int) Math.floor(bar);
F. Int foo = (int) Math.round(bar);
Answer: E
QUESTION NO: 65
Which statement is true?
A. A flow layout can be used to position a component that should resize horizontally when the
container is resized.
B. A grid layout can be used to position a component tat should maintain a constant size even when
the container is resized.
C. A border layout can be used to position component that should maintain a constant size even when
the container is resized.
D. The grid bag layout can be used to give a grid-like layout which differs from the normal grid in
that individual rows and columns can have unique sizes.
E. If two components are placed in the same column of a grid bag layout, and one component resizes
horizontally, then the other component must resize horizontally.
Answer: D
QUESTION NO: 66
Given an ActionEvent, which method allows you to identify the affected Component?
A. Public class getClass()
B. Public Object getSource()
C. Public Component getSource()
D. Public Component getTarget()
E. Public Component getComponent()
F. Public Component getTargetComponent()
Answer: B
QUESTION NO: 67
Exhibit:
1. import java.awt.*;
2.
3. public class Test extends Frame {
4. public Test() {
5. add(new Label(“Hello”) );
6. add(new TextField(“Hello”) );
7. add(new Button(“Hello”) );
8. pack();
9. show();
10. }
11.
12. public static void main(String args[]) {
13. new Test ();
14. }
15. )
What is the result?
A. The code will not compile.
B. A Window will appear containing only a Button.
C. An IllegalArgumentException is thrown at line 6.
D. A Window button will appear but will not contain the Label, TextField, or Button.
E. A Window will appear containing a Label at the top, a TextField below the Label, and a Button
below the TextField.
F. A Window will appear containing a Label on the left, a TextField to the right of the Label, and a
button to the right of the TextField.
Answer: B
QUESTION NO: 68
Exhibit:
1. class A {
2. public int getNumber(int a) {
3. return a + 1;
4. }
5. }
6.
7. class B extends A {
8. public int getNumber (int a) {
9. return a + 2
10. }
11.
12. public static void main (String args[]) {
13. A a = new B();
14. System.out.printIn(a.getNumber(0));
15. }
16. }
What is the result?
A. Compilation succeeds and 1 is printed.
B. Compilation succeeds and 2 is printed.
C. An error at line 8 causes compilation to fail.
D. An error at line 13 causes compilation to fail.
E. An error at line 14 causes compilation to fail.
Answer: B
QUESTION NO: 69
Given:
1. class BaseClass{
2. private float x= 1.0f;
3. protected void setVar (float f) {x = f;}
4. }

5. class SubClass exyends BaseClass {
6. private float x = 2.0f;
7. //insert code here
8. }
Which two are valid examples of method overriding? (Choose Two)
A. Void setVar(float f) {x = f;}
B. Public void setVar(int f) {x = f;}
C. Public void setVar(float f) {x = f;}
D. Public double setVar(float f) {x = f;}
E. Public final void setVar(float f) {x = f;}
F. Protected float setVar() {x=3.0f; return 3.0f; }
Answer: C, E 转

QUESTION NO: 70
Which statement about static inner classes is true?
A. An anonymous class can be declared as static.
B. A static inner class cannot be a static member of the outer class.
C. A static inner class does not require an instance of the enclosing class.
D. Instance members of a static inner class can be referenced using the class name of the static inner
class.
Answer: C
QUESTION NO: 71
Exhibit:
1. class A {
2. public byte getNumber () {
3. return 1;
4. }
5. }
6.
7. class B extends A {
8. public short getNumber() {
9. return 2;
10. }
11.
12. public static void main (String args[]) {
13. B b = new B ();
14. System.out.printIn(b.getNumber())
15. }
16. }
What is the result?
A. Compilation succeeds and 1 is printed.
B. Compilation succeeds and 2 is printed.
C. An error at line 8 causes compilation to fail.
D. An error at line 14 causes compilation to fail.
E. Compilation succeeds but an exception is thrown at line 14.
Answer: C
QUESTION NO: 72
Given:
AnInterface is an interface.
AnAdapter0 is a non-abstract, non-final class with a zero argument constructor.
AnAdapter1 is a non-abstract, non-final class without a zero argument constructor, but with a constructor that
takes one int argument.
Which two construct an anonymous inner class? (Choose Two)
F. AnAdapter1 aa=new AnAdapter1(){}
G. AnAdapter0 aa=new AnAdapter0(){}
H. AnAdapter0 aa=new AnAdapter0(5){}
I. AnAdapter1 aa=new AnAdapter1(5){}
J. AnInterface a1=new AnInterface(5){}
Answer: B, D
QUESTION NO: 73
Which two statements are true? (Choose Two)
A. An inner class may be declared as static.
B. An anonymous inner class can be declared as public.
C. An anonymous inner class can be declared as private.
D. An anonymous inner class can extend an abstract class.
E. An anonymous inner class can be declared as protected.
Answer: A, D
QUESTION NO: 74
Exhibit:
1. public class Mycircle {
2. public double radius;
3. public double diameter;
4.
5. public void setRadius(double radius)
6. this.radius = radius;
7. this.diameter= radius * 2;
8. }
9.
10. public double getRadius() {
11. return radius;
12. }
13. }
Which statement is true?
A. The Mycircle class is fully encapsulated.
B. The diameter of a given MyCircle is guaranteed to be twice its radius.
C. Lines 6 and 7 should be in a synchronized block to ensure encapsulation.
D. The radius of a MyCircle object can be set without affecting its diameter.
Answer: B
QUESTION NO: 75
You want to limit access to a method of a public class to members of the same class. Which access
modifier accomplishes this objective?
A. Public
B. Private
C. Protected
D. Transient
E. No access modifier is required
Answer: B
QUESTION NO: 76
Exhibit:
ClassOne.java
1. package com.abc.pkg1;
2. public class ClassOne {
3. private char var = ‘a';
4. char getVar() {return var;}
5. }
ClassTest.java
1. package com.abc.pkg2;
2. import com.abc.pkg1.ClassOne;
3. public class ClassTest extends ClassOne {
4. public static void main(String[]args) {
5. char a = new ClassOne().getVar();
6. char b = new ClassTest().getVar();
7. }
8. }
What is the result?
A. Compilation will fail.
B. Compilation succeeds and no exceptions are thrown.
C. Compilation succeeds but an exception is thrown at line 5 in ClassTest.java.
D. Compilation succeeds but an exception is thrown at line 6 in ClassTest.java.
Answer: B
QUESTION NO: 77
Given:
1. public class ArrayTest {
2. public static void main (String[]args) {
3. float f1[], f2[];
4. f1 = new float [10];
5. f2 = f1;
6. System.out.printIn (“f2[0]=” + f2[0]);
7. }
8. }
What is the result?
A. It prints f2[0] = 0.0
B. It prints f2[0] = NaN
C. An error at line 5 causes compile to fail.
D. An error at line 6 causes compile to fail.
E. An error at line 6 causes an exception at runtime.
Answer: A

QUESTION NO: 78
Which two statements are true regarding the creation of a default constructor? (Choose Two)
A. The default constructor initializes method variables.
B. The compiler always creates a default constructor for every class.
C. The default constructor invokes the no-parameter constructor of the superclass.
D. The default constructor initializes the instance variables declared in the class.
E. When a class has only constructors with parameters, the compiler does not create a default
constructor.
Answer: D, E
QUESTION NO: 79
Exhibit:
1. class super {
2. public int getLength() {return 4;}
3. }
4.
5. public class Sub extends Super {
6. public long getLength() {return 5;}
7.
8. public static void main (String[]args) {
9. super sooper = new Super ();
10. Sub sub = new Sub();
11. System.out.printIn(
12. sooper.getLength()+ “,” + sub.getLength() };
13. }
14. }
What is the output?
A. 4, 4
B. 4, 5
C. 5, 4
D. 5, 5
E. The code will not compile.
Answer: E
QUESTION NO: 80
Given:
1. public abstract class Test {
2. public abstract void methodA();
3.
4. public abstract void methodB()
5. {
6. System.out.printIn(“Hello”);
7. }
8. }
Which three changes (made independently) allow the code to compile? (Choose Three)
A. Add a method body to methodA.
B. Replace lines 5-7 with a semicolon (“.”)
C. Remove the abstract qualifier from the declaration of Test.
D. Remove the abstract qualifier from the declaration of methodB.
E. Remove the abstract qualifier from the declaration of methodA.
F. Remove methodB in its entirely and change class o interface in line 1.
Answer: B, D, F

QUESTION NO: 81
Which determines if “prefs” is a directory and exists on the file system?
A. Boolean exists=Directory.exists (“prefs”);
B. Boolean exists=(new File(“prefs”)).isDir();
C. Boolean exists=(new Directory(“prefs”)).exists();
D. Boolean exists=(new File(“prefs”)).isDirectory();
E. Boolean exists=true;
Try{
Directory d = new Directory(“prefs”);
}
catch (FileNotFoundException e) {
exists = false;
}
Answer: D
QUESTION NO: 82
Which two create an InputStream and open file the “file.txt” for reading? (Choose Two)
A. InputStream in=new FileReader(“file.txt”);
B. InputStream in=new FileInputStream(“file.txt”);
C. InputStream in=new InputStreamFileReader (“file.txt”, “read”);
D. FileInputStream in=new FileReader(new File(“file.txt”));
E. FileInputStream in=new FileInputStream(new File(“file.txt”));
Answer: B, E
QUESTION NO 83
Which two construct an OutputSream that appends to the file “file.txt”? (Choose Two)
A. OutputStream out=new FileOutputStream(“file.txt”);
B. OutputStream out=new FileOutputStream(“file.txt”, “append”);
C. FileOutputStream out=new FileOutputStream(“file.txt”, true);
D. FileOutputStream out=new FileOutputStream(new file(“file.txt”));
E. OutputStream out=new FileOutputStream(new File(“file.txt”)true);
Answer: C, E

QUESTION NO: 84
Which constructs a BufferedIputStream?
A. New BufferedInputStream(“in.txt”);
B. New BufferedInputStream(new File(“in.txt”));
C. New BufferedInputStream(new Writer(“in.txt”));
D. New BufferedInputStream(new Writer(“in.txt”));
E. New BufferedInputStream(new InputStream(“in.txt”));
F. New BufferedInputStream(new FileInputStream(“in.txt”));
Answer: F
QUESTION NO: 85
Which is a valid identifier?
A. false
B. default
C. _object
D. a-class
Answer: C
QUESTION NO: 86
Exhibit:
1. package foo;
2.
3. import java.util.Vector;
4.
5. private class MyVector extends Vector {
6. int i = 1;
7. public MyVector() {
8. i = 2;
9. }
10. }
11.
12. public class MyNewVector extends MyVector {
13. public MyNewVector () {
14. i = 4;
15. }
16. public static void main (String args []) {
17. MyVector v = new MyNewVector();
18. }
19. }
The file MyNewVector.java is shown in the exhibit.
What is the result?
A. Compilation will succeed.
B. Compilation will fail at line 5.
C. Compilation will fail at line 6.
D. Compilation will fail at line 14.
E. Compilation will fail at line 17.
Answer: B

QUESTION NO: 87
Given:
1. public class Test {
2. public static void main (String[]args) {
3. String foo = args[1];
4. String bar = args[2];
5. String baz = args[3];
6. System.out.printIn(“baz = ” + baz);
7. }
8. }
And the output:
Baz = 2
Which command line invocation will produce the output?
A. Java Test 2222
B. Java Test 1 2 3 4
C. Java Test 4 2 4 2
D. Java Test 4 3 2 1
Answer: C

QUESTION NO: 88
Given:
8. int index = 1;
9. String [] test = new String[3];
10. String foo = test[index];
What is the result?
E. Foo has the value “”
B. Foo has the value null
C. An exception is thrown
D. The code will not compile
Answer: B
QUESTION NO: 89
Given:
1. public interface Foo{
2. int k = 4;
3. }
Which three are equivalent to line 2? (Choose Three)
A. Final int k = 4;
B. Public int k = 4;
C. Static int k = 4;
D. Private int k = 4;
E. Abstract int k = 4;
F. Volatile int k = 4;
G. Transient int k = 4;
H. Protected int k = 4;
Answer: A, B, C
QUESTION NO: 90
Given:
310-025
Leading the way in IT testing and certification tools, www.testking.com
- 48 -
1. public class foo {
2. static String s;
3. public static void main (String[]args) {
4. system.out.printIn (“s=” + s);
5. }
6. }
What is the result?
A. The code compiles and “s=” is printed.
B. The code compiles and “s=null” is printed.
C. The code does not compile because string s is not initialized.
D. The code does not compile because string s cannot be referenced.
E. The code compiles, but a NullPointerException is thrown when toString is called.
Answer: B
QUESTION NO: 91
Which two valid declarations of a char? (Choose Two)
A. Char ch = “a”;
B. Char ch = ‘\' ‘;
C. Char ch = ‘cafe';
D. Char ch = “cafe”;
E. Char ch = ‘\ucafe';
F. Char ch = ‘\u10100';
G. Char ch = (char) true;
Answer: B, E 试