Two-Dimensional Arrays in Java (Exercise 1)

Java Programming: Programming Exercise on Two-Dimensional Arrays in Java Programming
Topics Discussed:
1) Writing a program that prints the sum of each row in a 2D array.
2) Writing a program that prints the sum of each column in a 2D array.

Music:
Axol x Alex Skrindo - You [NCS Release]

#JavaByNeso #JavaProgramming #ArraysInJava #2DArrays

[RizaHariati]

Very simple yet very clear explanation. Thank you!

[iivcvih]

Thank you very much for an excellent explanation

[marialourdesalindada]

This is awesome, simple and understandable.

[SKMTutorialsHub]

Very good explanation.. thank you so much sir.

[blakemccann]

It took me a little bit to figure out why I couldn't get mine to work like his.
In the video, the println statement is inside the inner for loop. This will cause it to print every iteration. Simply move the println statement one curly bracket down to fix this problem.

int[][] integers = {
{1, 2, 3, 4},
{5, 6, 7, 8},
{9, 10, 11, 12}
};

for(int i = 0; i < integers.length; i++) {
int sum = 0;
for(int j = 0; j < integers[i].length; j++) {
sum += integers[i][j];
> }
> System.out.println("The sum of row " + (i + 1) +": " + sum);
}

[.anugrahabar]

Sir i thank you for wonderful explanation it means a lot to me

[Decklun]

What if my array was a ragged array? Then it seems to become very difficult to get the sum of columns.

int[][] sumTest = {
{4, 5, 6},
{1, 2, 3},
{10, 10, 10, 10}
};

for (int i = 0; i < array[i].length; i++){
int sum = 0;
for (int j = 0; j < array.length; j++) {
sum += array[j][i];
}
System.out.println("Sum of column " + (i+1) + ": " + sum);
}

This gives me the sum for the first 3 columns but then gives an exception. "Index 3 out of bounds for length 3"

[sukursukur]

Hello from Turkiye. Thank you very much for crystal clear explanation.
We reduced 2d set into 1d set by summing each row. And if we want to use result set to calculate standard deviation, how will we import set elements into std formulation? Result doesnt seem as a set formate.

[abcshorts]

sir, object oriented programming par bhi video bnaye. plz

[yandakuditisandeep]

What if rows = column and we have to print the column sum?

[rohib]

for (int[] ints : number) {
for (int anInt : ints) System.out.println(anInt);
System.out.println();
}

[MikeLifexx]

Here's my solution for columns, which isn't as hard-coded.

class HelloWorld {

public static void main(String[] args) {
int[][] integers = {
{1, 2, 3, 4},
{5, 6, 7, 8},
{9, 10, 11, 12}
};

int[] sums = sumOfColumns(integers);
for(int i = 0; i < sums.length; i++) {
System.out.println("Sum of Column " + (i + 1) + ": " + sums[i]);
}

}

private static int[] sumOfColumns(int[][] intArray) {
int[] columnSums = new int[intArray[0].length];
int rowLength = intArray[0].length;
for(int i = 0; i < rowLength; i++) {
for(int j = 0; j < intArray.length; j++) {
columnSums[i] += intArray[j][i];
}
}
return columnSums;
}

}

[kvelez]

class App{
public static void main(String[] args) {

int[][] integers = {
{1, 2, 3, 4},
{5, 6, 7, 8},
{9, 10, 11, 12},
};

int value = 0;

for (int i = 0; i < integers.length; i++){
for (int j = 0; j < integers[i].length; j++){
value += integers[i][j];
}
System.out.println("Row " + (i+1) + " = " + value);
value = 0;
}



for (int i = 0; i < integers.length; i++){
for (int j = 0; j < integers.length; j++){
value += integers[j][i];
}
System.out.println("Column " + (i+1) + " = " + value);
value = 0;
}

}
}

[-MustakimMusa]

import java.util.Arrays;

class HelloWorld {
public static void main(String[] args) {
int[][] arr = {{1, 2, 3},
{4, 5, 6},
{7, 8, 9}
};

// Calculating row sums
for(int i=0; i< arr.length;i++) {
int sum=0;
for(int j=0;j<arr[i].length;j++) { // Corrected loop boundary
sum+=arr[i][j];
}
System.out.println("sum of row "+(i+1)+" "+sum);
}

// Calculating column sums
for(int i=0; i< arr[0].length; i++) { // Looping through columns
int sum=0;
for(int j=0;j<arr.length;j++) {
sum+=arr[j][i];
}
System.out.println("sum of column "+(i+1)+" "+sum);
}
}
}

[acunit]

public static void main(String[] args) {

int [][] numbers = {
{1, 2, 3, 4},
{5, 6, 7, 8},
{9, 10, 11, 12}
};
sumofArray(numbers);
sumofColumn(numbers);
}

private static void sumofColumn(int[][] numbers) {
int c1 = 0;
int c2 = 0;
int c3 = 0;
int c4 = 0;
for(int i = 0; i < numbers.length; i++){
for(int j = 0; j < numbers[i].length; j++ ){
switch (j) {
case 0: c1 += numbers[i][j];
break;
case 1: c2 += numbers[i][j];
break;
case 2: c3 += numbers[i][j];
break;
case 3: c4 += numbers[i][j];
break;
}
}
}
System.out.println("Sum of Column 1: "+c1);
System.out.println("Sum of Column 2: "+c2);
System.out.println("Sum of Column 3: "+c3);
System.out.println("Sum of Column 4: "+c4);
}

private static void sumofArray(int[][] numbers) {
for(int i = 0; i < numbers.length; i++){
int sum = 0;
for(int j = 0; j < numbers[i].length; j++) {
sum += numbers[i][j];

}
System.out.println("Sum of Row "+(i+1)+": "+sum);
}
}

[-MustakimMusa]

import java.util.Arrays;
class HelloWorld {
public static void main(String[] args) {
int[][] arr = {{1, 2, 3, 6},
{4, 5, 6, 5},
{7, 8, 9, 1}
};
for(int i=0; i< arr[0].length;i++) { // changed arr[i].length to arr[0].length
int sum=0;
for(int j=0;j<arr.length;j++) {
sum+=arr[j][i];
}
System.out.println(sum);
}
}
}

[-MustakimMusa]

/*
import java.util.Arrays;
class HelloWorld {
public static void main(String[] args) {
int[][] arr = {{1, 2, 3, 6},
{4, 5, 6, 5},
{7, 8, 9, 1}
};
for(int i=0; i< 4;i++) {
int sum=0;
for(int j=0;j<3;j++) {
sum+=arr[j][i];
}
System.out.println(sum);
}
}
}
*/

import java.util.Arrays;
class HelloWorld {
public static void main(String[] args) {
int[][] arr = {{1, 2, 3, 6},
{4, 5, 6, 5},
{7, 8, 9, 1}
};
for(int i=0; i< 3;i++) {
int sum=0;
for(int j=0;j<4;j++) {
sum+=arr[i][j];
}
System.out.println(sum);
}
}
}

[-MustakimMusa]

import java.util.Arrays;blu39
class HelloWorld {
public static void main(String[] args) {

int[][] arr = {{1, 2, 3, 1},
{4, 5, 6, 1},
{7, 8, 9, 1}
};
for(int i=0; i< 3;i++) {
int sum=0;
for(int j=0;j<4;j++) {
sum+=arr[i][j];
}
System.out.println("sum of each row "+sum);
}
for(int i=0; i< 4;i++) {
int sum=0;
for(int j=0;j<3;j++) {
sum+=arr[j][i];
}
System.out.println("sum of each column "+sum);
}

}
}

[kevinbanan]

static void sumOfRow (int[][] m) {

int sum = 0;
for(int i = 0; i < m.length; i++) {
for (int j = 0; j < m[0].length; j++) {
sum += m[i][j];
}
System.out.println("Sum of row " + (i + 1) + " = " + sum);
sum = 0;
}
}

static void sumOfCol (int[][] m) {
int sum = 0;
for (int i = 0; i < m[0].length; i++) {
for (int j = 0; j < m.length; j++) {
sum += m[j][i];
}
System.out.println("Sum of column " + (i + 1) + " = " + sum);
sum = 0;
}
}

[suswithcherry]

import java.util.*;

class Check {

public static void main(String[] args) {

int[][] integers = {{1, 2, 3, 0}, {4, 5, 0, 0}, {6, 7, 8, 9}};

sumByRow(integers);
sumByColumn(integers);
}

private static void sumByRow(int[][] integers) {
int sum = 0;

for(int i = 0; i < integers.length; i++) {
for(int j = 0; j < integers[i].length; j++)
sum += integers[i][j];

System.out.println("Sum of Row " + (i+1) + " is: " + sum);
sum = 0;
}
}

private static void sumByColumn(int[][] integers) {
int sum = 0;

for(int i = 0; i < integers.length + 1; i++) { // {{1, 2, 3, 0}, {4, 5, 0, 0}, {6, 7, 8, 9}}
for(int j = 0; j < integers.length; j++)
sum += integers[j][i];

System.out.println("Sum of Column " + (i+1) + " is: " + sum);
sum = 0;
}
}
}