created: Jan. 06, 2000; revised: 10/05/03, 06/05/06, 07/05/07


on ArrayLists and Iterators

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1. Declare and construct an ArrayList with an initial capacity of 20 references to Object.

A.    Object list(20) = new ArrayList() ;
B.    ArrayList list[20] = new ArrayList() ;
C.    ArrayList[Object] list = new ArrayList(20) ;
D.    ArrayList<Object> list = new ArrayList<Object>(20) ;

2. Examine the following code:

ArrayList<String> list = new ArrayList<String>(10) ;
list.add( "Ann" );
list.add( "Bob" );
list.add( "Eve" );

After the code has exectued, what is the capactiy of list? What is its size?

A.    3, 3
B.    3, 10
C.    10, 3
D.    10, 10

3. Examine the following code:

ArrayList<String> list = new ArrayList<String>(10) ;

list.add( "Andy" );
list.add( "Bart" );
list.add( "Carl" );
list.add( 0, "Eve" );

What element will be at index 2 of the list?

A.    Eve
B.    Andy
C.    Bart
D.    carl

4. Examine the following code:

ArrayList<String> list = new ArrayList<String>() ;

list.add( "Andy" );
list.add( "Bart" );
list.add( "Carl" );
list.add( "Doug" );
list.add( "Elmo" );

Which of the following will replace the element "Carl" with "Zoltan" ?

A.    list[2] = "Zoltan" ;
B.    list.set( "Zoltan", "Carl" );
C.    list.add( "Zoltan", list.indexOf("Carl") );
D.    list.set( list.indexOf("Carl"), "Zoltan" );

5. Examine the following code:

ArrayList<String> list = new ArrayList<String>() ;

list.add( "Andy" );
list.add( "Bart" );
list.add( "Carl" );
list.add( "Doug" );
list.add( "Elmo" );

Which of the following will change the list so that it looks like:

Andy
Bart
Carl
Doug
Oscar
Elmo

A.    list.add( 3, "Oscar" ) ;
B.    list.add( 4, "Oscar" ) ;
C.    list.set( 3, "Oscar" ) ;
D.    list.set( 4, "Oscar" ) ;

6. Examine the following code:

ArrayList<String> list = new ArrayList<String>() ;

list.add( "Andy" );
list.add( "Bart" );
list.add( "Carl" );
list.add( "Doug" );
list.add( "Elmo" );

Which of the following will change the list so that it looks like:

Andy
Bart
Doug
Elmo

A.    list.remove( 3 );
B.    list.remove( 2 );
C.    list.add( 2, null );
D.    list.set( list.indexOf( "Carl" ), "Doug" );

7. Examine the following code:

ArrayList<String> list = new ArrayList<String>() ;

list.add( "Andy" );
list.add( "Bart" );
list.add( "Carl" );
list.add( "Doug" );
list.add( "Elmo" );

Which of the following will change the list so that it looks like:

Andy
Bart
Carl
Doug

A.    list.remove( list.size() );
B.    list.remove( list.size()-1 );
C.    list.remove( 5 );
D.    list.clear( "Elmo" );

8. Examine the following code:

ArrayList<String> list = new ArrayList<String>() ;

list.add( "Andy" );
list.add( "Bart" );
list.add( "Carl" );
list.add( "Doug" );
list.add( "Elmo" );

Iterator iter = list.___________________;

while( iter.___________ )
  System.out.println( iter.___________ );

Fill in the blanks so that the list is printed.

A.    iterator()       hasNext()     next()
B.    iterator()       next()        nextElement()
C.    elements()       empty()       next()
D.    iterator()       more()        get()

9. Examine the following code:

ArrayList<String> list = new ArrayList<String>() ;

list.add( "Andy" );
list.add( "Bart" );
list.add( "Carl" );
list.add( "Doug" );
list.add( "Elmo" );

while( ________ name : ___________ )
  System.out.println( ___________ );

Fill in the blanks so that the list is printed.

A.    String       list        name
B.    String       iterator()    next()
C.    int          String         name
D.    iterator()    String        list

10. which of the following declarations would be appropriate for a list that is expected to contain integers?

A.    ArrayList<String> list = new ArrayList<String>() ;
B.    ArrayList<int> list = new ArrayList<int>() ;
C.    ArrayList<Integer> list = new ArrayList<Integer>() ;
D.    ArrayList list = new ArrayList() ;

11. What is the interface implemented by a class (such as ArrayList) that implements the iterator() method?

A.    Iterator
B.    Iterable

12. What is the interface implemented by an iterator object itself?

A.    Iterator
B.    Iterable

13. What is true of classes that can be used with the enhanced for loop?

A.    All classes can use the enhanced for loop.
B.    Only ArrayList can use the enhanced for loop.
C.    Only ArrayList and arrays can use the enhanced for loop.
D.    Any class that implements Iterable can use the enhanced for loop.

14. What equals() method must you override when defining a class of objects you expect to hold in a ArrayList ?

A.    public boolean equals( Object )
B.    public boolean equals( ArrayList )
C.    boolean equals( Object )
D.    private int equals( Object )

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