Chapter 9 - Reading and Understanding Code

Question 1

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

14. How many rows are in the array cities?

Answer 1

4

Question 2

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

15. What is the value of the expression cities[2][1]?

Answer 2

Ajaccio

Question 3

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

16. What is the index of the last row in the array cities?

Answer 3

3

Question 4

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

17. What are the row and column indexes of Chicago in the array cities?

Answer 4

row 0 and column 3

Question 5

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

18. What is the output of this code sequence?
    System.out.println( cities[3][2] );

Answer 5

Vancouver

Question 6

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

19. What is the output of this code sequence?

for ( int j = 0; j < cities[1].length; j++ )
System.out.println( cities[1][j] );

Answer 6

Munich
Stuttgart
Berlin
Bonn

Question 7

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

20. What is the output of this code sequence?

for ( int i = 0; i < cities.length; i++ )
System.out.println( cities[i][1] );

Answer 7

LA
Stuttgart
Ajaccio
Ottawa

Question 8

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

21. What is the output of this code sequence?

for ( int i = 0; i < cities.length; i++ )
{
for ( int j = 0; j < cities[i].length; j++ )
System.out.print( cities[i][j] + “\t” );
System.out.println( );
}

Answer 8

New York LA San Francisco Chicago
Munich Stuttgart Berlin Bonn
Paris Ajaccio Lyon
Montreal Ottawa Vancouver

Question 9

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

22. What is the output of this code sequence?

for ( int i = 0; i < cities.length; i++ )
{
for ( int j = 0; j < cities[i].length; j++ )
{
if ( cities[i][j].length( ) == 6 )
System.out.println( cities[i][j] );
}
}

Answer 9

Munich
Berlin
Ottawa

Question 10

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

23. What is the output of this code sequence?

int count = 0;
for ( int i = 0; i < cities.length; i++ )
{
for ( int j = 0; j < cities[i].length; j++ )
{
if ( cities[i][j].length( ) == 7 )
count++;
}
}
System.out.println( “count is “ + count );

Answer 10

count is 2

Question 11

For Questions 14 to 24, consider the following two-dimensional array declaration and initialization:

String [ ][ ] cities = {
{ “New York”, “LA”, “San Francisco”, “Chicago”}, { “Munich”, “Stuttgart”, “Berlin”, “Bonn” }, { “Paris”, “Ajaccio”, “Lyon” }, { “Montreal”, “Ottawa”, “Vancouver” } };

24. What is the output of this code sequence?

for ( int i = 0; i < cities.length; i++ )
{
for ( int j = 0; j < cities[i].length; j++ )
{
if ( cities[i][j].charAt( 0 ) == ‘S’ )
System.out.println( cities[i][j] );
}
}

Answer 11

San Francisco

Stuttgart

Question 12

25. What does this method do?

public static int foo( double [ ][ ] a )
{
      int b = 0;
      for ( int i = 0; i < a.length; i++ )
      {
         for ( int j = 0; j < a[i].length; j++ )
                 b++;
      }
      return b;
}

Answer 12

. It counts and returns the number of elements in the parameter array a

Question 13

26. What does this method do?

public static boolean foo( char [ ][ ] a )
{
   int b = a[0].length;
   for ( int i = 1; i < a.length; i++ )
   {
         if ( a[i].length != b )
            return false;
   }
   return true;
}

Answer 13

It returns true if all the rows of the argument array a have the same number of
columns; otherwise, it returns false

Question 14

27. What does this method do?

public static int foo( String [ ][ ] a )
{
      int b = 0;
      for ( int i = 0; i < a.length; i++ )
            b++;
      return b;
}

Answer 14

. It returns the number of rows in the argument array a

Question 15

28. What does this method do?

public static int [ ] foo( float [ ][ ] a )
{
int [ ] temp = new int [a.length];
for ( int i = 0; i < a.length; i++ )
temp[i] = a[i].length;
return temp;
}

Answer 15

It returns an int array of the same length as the length of the array parameter a.
Each element of the returned array stores the number of columns of the
corresponding row in a.

Question 16

29. What does this method do?

public static int foo( ArrayList a )
{
      int b = 0;
      for ( Integer i : a )
          b++;
      return b;
}

Answer 16

It returns the number of elements in the ArrayList argument a

Question 17

30. After the following code sequence is executed, what are the contents and index of each element of a?

ArrayList a = new ArrayList( );

a. add( 7 );
a. add( 4 );
a. add( 21 );

Answer 17

7 (at index 0) 4 (at index 1) 21 (at index 2)

Question 18

31. After the following code sequence is executed, what are the contents and index of each element of a?

ArrayList a = new ArrayList( );

a. add( 7 );
a. add( 4 );
a. add( 21 );
a. set( 1, 45 );

Answer 18

7 (at index 0) 45 (at index 1) 21 (at index 2)

Question 19

32. After the following code sequence is executed, what are the contents and index of each element of a?

ArrayList a = new ArrayList( );

a. add( 7 );
a. add( 4 );
a. add( 21 );
a. add( 1, 45 );

Answer 19

7 (at index 0) 45 (at index 1) 4 (at index 2) 21 (at index 3)