147题付答案，我把它贴出来（续）

18. Which three are valid declarations of a float? (Choose Three)

A. float foo = -1; B. float foo = 1.0; C. float foo = 42e1; D. float foo = 2.02f; E. float foo = 3.03d; F. float foo = 0x0123;

19. Given:

8. int index = 1; 9. boolean[] test = new Boolean[3]; 10. boolean foo= test [index];

What is the result?

A. foo has the value of 0 B. foo has the value of null C. foo has the value of true D. foo has the value of false E. an exception is thrown F. the code will not compile

20. Given:

1. public class test( 2. public static void main(string[]args){ 3. string foo = args [1]; 4. string foo = args [2]; 5. string foo = args [3]; 6. } 7. }

And the command line invocation: Java Test red green blue

What is the result?

A. baz has the value of “” B. baz has the value of null C. baz has the value of “red” D. baz has the value of “blue” E. bax has the value of “green” F. the code does not compile G. the program throws an exception

21. Given:

8. int index = 1; 9. int [] foo = new int [3]; 10. int bar = foo [index]; 11. int baz = bar + index;

What is the result?

A. baz has the value of 0 B. baz has the value of 1 C. baz has the value of 2 D. an exception is thrown E. the code will not compile

22. Given:

1. public class foo { 2. public static void main (String[]args) { 3. String s; 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.

23. Which will declare a method that forces a subclass to implement it?

A. Public double methoda(); B. Static void methoda (double d1) {} C. Public native double methoda(); D. Abstract public void methoda(); E. Protected void methoda (double d1){}

24. You want subclasses in any package to have access to members of a superclass. Which is the most restrictive access modifier that will accomplish this objective?

A. Public B. Private C. Protected D. Transient E. No access modifier is qualified

25. Given:

1. abstract class abstrctIt { 2. abstract float getFloat (); 3. ) 4. public class AbstractTest extends AbstractIt { 5. private float f1= 1.0f; 6. private float getFloat () {return f1;} 7. }

What is the result?

A. Compilation is successful. B. An error on line 6 causes a runtime failure. C. An error at line 6 causes compilation to fail. D. An error at line 2 causes compilation to fail.

26. Click the exhibit button:

1. public class test( 2. public int aMethod()[ 3. static int i=0; 4. i++; 5. return I; 6. ) 7. public static void main (String args[]){ 8. test test = new test(); 9. test.aMethod(); 10. int j = test.aMethod(); 11. System.out.printIn(j); 12. ] 13. }

What is the result?

A. Compilation will fail. B. Compilation will succeed and the program will print “0”. C. Compilation will succeed and the program will print “1”. D. Compilation will succeed and the program will print “2”.

27. Given:

1. class super { 2. public float getNum() {return 3.0f;} 3. ) 4. 5. public class Sub extends Super { 6. 7. )

Which method, placed at line 6, will cause a compiler error?

A. public float getNum() {return 4.0f; } B. public void getNum () { } C. public void getNum (double d) { } D. public double getNum (float d) {retrun 4.0f; }

28. Which declaration prevents creating a subclass of an outer class?

A. static class FooBar{} B. private class FooBar{} C. abstract public class FooBar{} D. final public class FooBar{} E. final abstract class FooBar{}

29. Given:

1. byte [] arry1, array2[]; 2. byte array3 [][]; 3. byte[][] array4;

If each array has been initialized, which statement will cause a compiler error?

A. array2 = array1; B. array2 = array3; C. array2 = array4; D. both A and B E. both A and C F. both B and C

30. Click the exhibit button:

1. class super ( 2. public int I = 0; 3. 4. public super (string text) ( 5. I = 1 6. ) 7. ) 8. 9. public class sub extends super ( 10. public sub (string text) ( 11. i= 2 12. ) 13. 14. public static void main (straing args[]) ( 15. sub sub = new sub (“Hello”); 16. system.out. PrintIn(sub.i); 17. ) 18. )

What is the result? A. Compilation will fail. B. Compilation will succeed and the program will print “0”. C. Compilation will succeed and the program will print “1”. D. Compilation will succeed and the program will print “2”.

31. Given:

1. public class returnIt ( 2. returnType methodA(byte x, double y) ( 3. return (short) x/y * 2; 4. ) 5. )

What is the valid returnType for methodA in line 2?

A. int B. byte C. long D. short E. float F. double

32. Given the ActionEvent, which method allows you to identify the affected component?

A. getClass B. getTarget C. getSource D. getComponent E. getTargetComponent

33. Which is a method of the MouseMotionListener interface?

A. Public void mouseMoved(MouseEvent) B. Public boolean mouseMoved(MouseEvent) C. Public void mouseMoved(MouseMotionEvent) D. Public boolean MouseMoved(MouseMotionEvent) E. Public boolean mouseMoved(MouseMotionEvent)

34. Click the exhibit button:

1. import java.awt*; 2. 3. public class X extends Frame ( 4. public static void main(string []args) ( 5. X x = new X (); 6. X.pack(); 7. x.setVisible(true); 8. ) 9. 10. public X () ( 11. setlayout (new GridLayout (2,2)); 12. 13. Panel p1 = new panel(); 14. Add(p1); 15. Button b1= new Button (“One”); 16. P1.add(b1); 17. 18. Panel p2 = new panel(); 19. Add(p2); 20. Button b2= new Button (“Two”); 21. P2.add(b2); 22. 23. Button b3= new Button (“Three”); 24. add(b3); 25. 26. Button b4= new Button (“Four”); 27. add(b4); 28. ) 29. )

Which two statements are true? (Choose Two)

A. All the buttons change height if the frame height is resized. B. All the buttons change width if the Frame width is resized. C. The size of the button labeled “One” is constant even if the Frame is resized. D. Both width and height of the button labeled “Three” might change if the Frame is resized.

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