2 D Arrays in Java Assignments

Add the following Methods to a class called ArrayFun2D

public void print(int[][] arr)

Description: This method prints each element in the array. This will be a useful method when you are debugging your code and want to test it out to see if it works.

Method Call return value
print({{1,2} , {3,4}, { 5, 6 } } ) 1   2
3  4
5   6

public int sum(int[][] arr)

Description: This method returns the sum of all elements in the array

Method Call return value
sum({{1,2} , {3,4}, { 5, 6 } } ) 21 ( ie 1+2+3+4+5+6)

public String concat(String[][] strs)

Description: This method returns the concatenation of all the elements in the Array

Method Call return value
concat({{“a”,”xc” }, {“t”, “zoo”}, { “jjkj” } } ) “axctzzoojjkj”

public double mean( int[][] arr)

Description: This method returns the arithmetic mean of the array. Make sure you double check that you are correctly returning results that include decimal values .

Method Call return value
mean({{2,8} , {4 , 7} } )  5.25 ie (2+8+4+7)/4

public void printRow(int[][] arr, int row)

Description: This method prints all elements in rowThis can be (and should be) done with a single loop.

Method Call return value
printRow({{1,2} , {3,4}, { 5, 6 } } , 1 ) 3, 4
printRow( { 5 , 6} , {7, 12, 13 , 5 }, { 5, 6 ,0} } , 2 ) 5 , 6, 0

public void printCol(int[][] arr, int col)

Description: This method prints all elements in col

Method Call return value
printCol({{1,2} , {3, 4}, { 5, 6 } } , 1 ) 2
4
6
printCol( { 5 , 6} , {7, 12, 13 , 5 }, { 12, 6 ,0} } , 0 ) 5
7
12
printCol(    {12, 13 , 5 }, { 6, 2, 13 ,11}  , {1,2 } } , 2 ) 5
13

public int maxVal_inRow(int[][] arr, int row)

Description: This method returns the value of the largest number in the given row

Method Call return value
maxVal_inRow({{1,2} , {3,4}, { 5, 6 } } , 1 ) 4
maxVal_inRow ({   { 5 , 6} , {7, 12, 13 , 5 }, { 5, 6 ,0} } , 2 ) 6

public int maxVal_inCol(int[][] arr, int col)

Description: This method returns the value of the largest number in the given col

Method Call return value
maxVal_inCol({{1,2} , {3,4}, { 5, 6 } } , 0 ) 5
maxVal_inCol({{1,-2} , {3,-4}, { 5, -5 } } , 1 ) -2

public int[][] changeValues(int[][] table, int val)

Description:This method returns the array with all elements set toval

changeValues(table, 5)

Original Array

1 2
3 4
5 6
Returned Array

5 5
5 5
5 5

public void print_colMajor(int[][] arr)

Description: This method prints each element in the array – using column major order

Method Call return value
print({{1,2} , {3,4}, { 5, 6 } } ) 1   3   5
2  4    6

 

public int[][] removeVals(int[][] table, int val)

Description: This method returns a version of the 2-d array where val has been removed from all elements

removeValues(table, 5)

Original Array

{1 , 5}
{3, 4}
{5, 6}
Returned Array

{1}
{3, 4}
{6}

 

int[] twoD_to1D(int[][] arr)

Description: This method takes an input array that is in 2 dimensions  and  creates a 1 d array . Assume that the array is rectangular (not jagged).

Method Call return value
twoD_to1D ( {{1,2} , {3,4}, { 5, 6 } } ) { 1 , 2 ,  3 ,  4 , 5 ,  6 }

Matrices

int[][] add (int[][] matr1, int[][] matr2)

Description: This method returns the sum of matr1 and matr2

how to add matrices


 

** int[][] multiply(int[][] matr1, int[][] matr2)

Description: This method returns the product of matr1 and matr2

how to multiply matrices

**public int[][] invertValues(int[][] matr)

Description: This method returns the paramater with its values ‘inverted’

Original Array

1 2
3 4
5 6
Returned Array

6 5
4 3
2 1