created: Jan. 06, 2000; revised: 10/05/03, 06/05/06, 07/05/07, 11/02/2012, 07/20/2016


worm on ArrayLists and Iterators

Instructions: For each question, choose the single best answer. Make your choice by clicking on its button. You can change your answers at any time. When the quiz is graded, the correct answers will appear in the box after each question.


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) ;

Correct Answer:


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 executed, what is the capacity of list? What is its size?

A.    3, 3

B.    3, 10

C.    10, 3

D.    10, 10

Correct Answer:


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

Correct Answer:


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" );

Correct Answer:


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" ) ;

Correct Answer:


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" );

Correct Answer:


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" );

Correct Answer:


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()

Correct Answer:


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

Correct Answer:


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() ;

Correct Answer:


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

A.    Iterator<E>

B.    Iterable

Correct Answer:


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

A.    Iterator<E>

B.    Iterable

Correct Answer:


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.

Correct Answer:


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 )

Correct Answer:


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