B4 - Two-dimensional Arrays

Examine the following:

double[][] values =

{ {1.2, 9.0, 3.2},

{9.2, 0.5, 1.5, -1.2},

{7.3, 7.9, 4.8} } ;

what is in values[2][1] ?

• 7.3

• 7.9

• 9.2

• There is no such array element.

Examine the following:

double[][] values =

{ {1.2, 9.0, 3.2},

{9.2, 0.5, 1.5, -1.2},

{7.3, 7.9, 4.8} } ;

what is in values[3][0] ?

• 7.3

• 7.9

• 9.2

• There is no such array element.

You want to create a table that looks like:

Which of the following will work?

• double[][] table =

  { 12, -9, 8,

  7, 14,

  -32, -1, 0} ;

• double[][] table =

  { {12, -9, 8},

  {7, 14, 0},

  -32, -1, 0} };

• double[][] table =

  { {12, -9, 8}

  {7, 14}

  {-32, -1, 0} };

• double[][] table =

  { {12, -9, 8},

  {7, 14},

  {-32, -1, 0} };

Given the following:

double[][] things =

{ {1.2, 9.0},

{9.2, 0.5, 0.0},

{7.3, 7.9, 1.2, 3.9} } ;

What is the value of things.length ?

• 2

• 3

• 4

• 9

Given the following:

double[][] things =

{ {1.2, 9.0},

{9.2, 0.5, 0.0},

{7.3, 7.9, 1.2, 3.9} } ;

What is the value of things[2].length ?

• 2

• 3

• 4

• 9

Given the following:

long[][] stuff ;

Which of the following statements constructs an array with 5 rows of 7 columns each and assign its reference to stuff ?

• stuff = new stuff[5][7] ;

• stuff = new long[5][7] ;

• stuff = long[5][7] ;

• stuff = long[7][5] ;

Given the following:

int[][] items =

{ {0, 1, 3, 4},

{4, 3, 99, 0, 7 },

{3, 2} } ;

Which of the following statements replaces the 99 with 77?

• items[1][2] = 77;

• items[2][1] = 77;

• items[ 99 ] = 77;

• items[2][3] = 77;

Which of the following constructs and assigns to array a 2D array with 7 rows, but does not yet construct the rows?

• int[][] array = new int[7][];

• int[][] array = new int[7];

• int[][] array = new int[][7];

• int[] array[7] = new int[];

Given:

int[][] items =

{ {0, 1, 3, 4},

{4, 3, 99, 0, 7 },

{3, 2} } ;

Which of the following fragments prints out every element of items?

• for ( int row=0; row < items.length; row++ )

  {

  System.out.println();

  for ( int col=0; col < items.length; col++ )

  System.out.print( items[row][col] + " ");

  }

• for ( int row=0; row < items.length; row++ )

  {

  System.out.println();

  for ( int col=0; col < items[col].length; col++ )

  System.out.print( items[row][col] + " ");

  }

• for ( int row=0; row < items.length; row++ )

  {

  System.out.println();

  for ( int col=0; col < items[row].length; col++ )

  System.out.print( items[row][col] + " ");

  }

• for ( int row=0; row < items.length; row++ )

  {

  for ( int row=0; row < items[row].length; row++ )

  System.out.print( items[row][col] + " ");

  System.out.println();

  }

Given:

int[][] items =

{ {0, 1, 3, 4},

{4, 3, 99, 0, 7 },

{3, 2} } ;

Which of the following fragments replaces row 0 of items with an entierly new row?

• items[0][0] = 8;

  items[0][1] = 12;

  items[0][2] = 6;

• items[0] = { 8, 12, 6 };

• items[0] = new { 8, 12, 6 };

• int[] temp = { 8, 12, 6 };

  items[0] = temp;