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Multi-Dimesional Array with User Input

Trying to change this code so I can get user input instead of a predefined array. Can anyone help? This code needs to have the method sum with the double[][] parameter. The method should return the sum of the elements of the array passed to it and should be rectangular.
import java.util.Scanner;
class Array2_1
{
public static double sum (double[][] array)
{
double sum = 0;
for (int i = 0; i < array.length; i++)
{
for (int j = 0; j < array[0].length; j++)
{
sum += array[i][j];
}
}
return sum;
}
public static void main(String[] args)
{
System.out.println("")
double a [][] = {
{1.2, 2},
{6, 7.2},
{11, 12}
};
System.out.println(sum(a));
}
}

You can use Scanner to read values from the keyboard. First, read the values for the dimensions of the array and then input values for the individual indices using nested loops.
You can also define a method to display the array in the tabular form.
Demo:
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter the number of rows: ");
int rows = scanner.nextInt();
System.out.print("Enter the number of columns: ");
int cols = scanner.nextInt();
double array[][] = new double[rows][cols];
for (int i = 0; i < array.length; i++) {
for (int j = 0; j < array[i].length; j++) {
System.out.printf("Enter value for array[%d][%d]: ", i, j);
array[i][j] = scanner.nextDouble();
}
}
System.out.println("The array:");
print(array);
System.out.println("Sum of elements: " + sum(array));
}
public static double sum(double[][] array) {
double sum = 0;
for (int i = 0; i < array.length; i++) {
for (int j = 0; j < array[i].length; j++) {
sum += array[i][j];
}
}
return sum;
}
public static void print(double[][] array) {
for (double[] row : array) {
for (double col : row) {
System.out.print(col + "\t\t");
}
System.out.println();
}
}
}
A sample run:
Enter the number of rows: 3
Enter the number of columns: 2
Enter value for array[0][0]: 1.2
Enter value for array[0][1]: 2
Enter value for array[1][0]: 6
Enter value for array[1][1]: 7.2
Enter value for array[2][0]: 11
Enter value for array[2][1]: 12
The array:
1.2 2.0
6.0 7.2
11.0 12.0
Sum of elements: 39.4

I have added comments to the code for your understanding. Hope it answers your query.
public static void main(String[] args) {
//You can use the Scanner class for taking input
Scanner scan = new Scanner(System.in);
//take input for the number of rows in array
System.out.println("Enter no. of rows in array");
int row = scan.nextInt();
//take input for the number of columns in array
System.out.println("Enter no. of columns in array");
int col = scan.nextInt();
//create an array with row and col as dimensions of the 2D array
double[][] arr = new double[row][col];
//this for loop is for inputting elements in your array
for (int i = 0; i < row; i++)
for (int j = 0; j < col; j++)
arr[i][j] = scan.nextInt();
//this for loop is for printing out the elements
for (int i = 0; i < row; i++) {
for (int j = 0; j < col; j++)
System.out.print(arr[i][j] + " ");
System.out.println();
}
scan.close();
//now give a call to your sum() method and print the result
System.out.println(sum(arr));
}

How to print results of matched numbers with a space

Just thought of a simple program to practice java coding and am stuck at the end part.,..
the code prints out the required answer (what numbers match from input compared to results for a 5 number lottery) but the answer is printed without spaces. I thought perhaps to add a "" when += to matchingNumbers but that didnt do anything!
import java.util.Scanner;
import java.util.Arrays;
public class LottoChecker
{
public static void main (String[] args)
{
Scanner in = new Scanner(System.in);
int [] yourNumbers = new int [5];
int yourInput, resultsInput;
int [] results = new int [5];
int currentNumber = 0;
String matchingNumbers = "";
for (int i=0; i<yourNumbers.length; i++)
{
System.out.println ("Enter your main numbers: " );
yourInput = in.nextInt();
yourNumbers[i]=yourInput;
}
for (int j=0; j<results.length; j++)
{
System.out.println("Enter the results from the main numbers: ");
resultsInput = in.nextInt();
results[j] = resultsInput;
}
System.out.println("Your Numbers: " +
Arrays.toString(bubbleSort(yourNumbers)));
System.out.println("The Results are: " +
Arrays.toString(results));
for (int i =0; i<yourNumbers.length;i++)
{
currentNumber = yourNumbers[i];
for (int j=0;j<results.length;j++)
if (currentNumber == results[j])
matchingNumbers += currentNumber + "";
}
System.out.println("Your matching numbers are: " +
matchingNumbers);
}
public static int [] bubbleSort(int arr[])
{
int n = arr.length;
for (int i = 0; i < n-1; i++)
for (int j = 0; j < n-i-1; j++)
if (arr[j] > arr[j+1])
{
int temp = arr[j];
arr[j] = arr[j+1];
arr[j+1] = temp;
}
return arr;
}
}

An elegant solution would be using StringJoiner(" ") and then add the numbers on each iteration.

Accessing array in private class

I am confused on how to access the array temp in order to compare the current array element temp[i] to max sales which is 0 in order to determine which is bigger,each time i try i cannot access temp IN STEP 8 and STEP 7, i do not want to change the visibility of the classes
public class Sales {
public static void main(String[] args) {
int[] sales;
sales = getSales();
printSales(sales);
printSummary(sales);
}
private static int[] getSales() {
Scanner input = new Scanner(System.in);
int[] temp;
System.out.print("Enter the number of salespeople: ");
temp = new int[input.nextInt()]; // Step 1
for (int i = 0; i < temp.length; i++) // Step 2
{
System.out.print("Enter sales for salesperson " + (i + 1) + ": ");
temp[i] = input.nextInt(); // Step 3
}
return temp; // Step 4
}
private static void printSales(int[] s) {
System.out.println();
System.out.println("Salesperson Sales");
System.out.println("----------- -----");
for (int i = 0; i < 5; i++) // Step 5
{
System.out.printf("%6d%12d\n", i + 1, s[i]); // Step 6
}
}
private static void printSummary(int[] s) {
int sum = 0;
int max_sale = 0; // Salesperson with the most sales
int min_sale = 0; // Salesperson with the least sales
for (int i = 0; i < ________; i++) // Step 7
{
____________ // Step 8
}
System.out.println();
System.out.println("Total sales: " + sum);
System.out.println("Average sales: " + (double) sum / s.length);
System.out.println("Salesperson " + (max_sale + 1) + " had the maximum sale with " + s[max_sale]);
System.out.println("Salesperson " + (min_sale + 1) + " had the minimum sale with " + s[min_sale]);
}
}

temp is a local variable that had been created in the main and passed to your printSummary(int[] s) method, so there you can access it by using s.
for (int i = 0; i < s.length; i++) { // STEP 7
if (s[i] > max_sale) max_sale = s[i]; // STEP 8
if (s[i] < min_sale) min_sale = s[i];
sum += s[i];
}

Took Andrew Tobilko code and changed it to save the index to the person that has highest sale value. Implementing this replacing your loop will work.
for (int i = 0; i < s.length; i++) { // STEP 7
if (s[i] > s[max_sale]) max_sale = i; // STEP 8
if (s[i] < s[min_sale]) min_sale = i;
sum += s[i];
}

This works at step 7/8 thanks to #andrew
int max = 0;
int min = Integer.MAX_VALUE;
for (int i= 0; i < s.length; i++) {
sum += s[i];
if (s[i] > max) {
max_sale = i;
max = s[i];
}
if (s[i] < min) {
min_sale = i;
min = s[i];
}
}

Simple Java Fibonacci code issue

import java.util.Scanner;
public class Fibonacci
{
public static void main(String[] args)
{
int count;
Scanner in = new Scanner(System.in);
System.out.println("Please enter number");
count = in.nextInt();
int[] fib = new int [count];
fib[0] = 1;
fib[1] = 1;
for (int i=2; i<count; i++)
{
fib[i] = fib[i-1] + fib[i-2];
}
for(int i=0; i<count; i++)
{
System.out.print(fib[i] + " ");
}
}
}
This is my very simple Fib program, what i cant figure out is why it always stops one number short. For example:
run: Please enter number 6 1 1 2 3 5 8 BUILD SUCCESSFUL (total time: 5
seconds)
run: Please enter number 7 1 1 2 3 5 8 13 BUILD SUCCESSFUL (total
time: 5 seconds)
I thought in my FOR loops it should be "(int i=2; i <= count;"
but when i put in greater than or equal to in both, or either FOR loop it gives me an error
Any suggestions? i know its something easy i'm overlooking

Your code is giving correct output. but still if you need one more element try to initialize array with count + 1 and then have your loop running for i <= count
public static void main(String[] args) {
int count;
Scanner in = new Scanner(System.in);
System.out.println("Please enter number");
count = in.nextInt();
int[] fib = new int [count+1];
fib[0] = 1;
fib[1] = 1;
for (int i=2; i <= count; i++){
fib[i] = fib[i-1] + fib[i-2];
}
for(int i=0; i <= count; i++){
System.out.print(fib[i] + " ");
}
}
}

Arrays are zero-based. This means, that (assuming count = 5) if you have the following array:
int[] fib = new int[5];
then you can access fib[0], fib[1], fib[2], fib[3] and fib[4]. So
for (int i = 0; i < 5; i++) {
System.out.print(fib[i] + " ");
}
would be fine. As it would access everything in fib, starting with index 0, and stopping with the last index smaller than 5, which is 4. However, if you do:
for (int i = 0; i <= 5; i++) {
System.out.print(fib[i] + " ");
}
then you will access the last index smaller than OR EQUAL TO 5, which is 5. But, as stated before, fib[5] is invalid. That's what gives you your error.

A simpler solution is to avoid needing an array in the first place and you don't need to get the size right.
public static void main(String[] args) {
System.out.println("Please enter a number");
Scanner in = new Scanner(System.in);
int count = in.nextInt();
long a = 1, b = 1;
for(int i = 0; i < count; i++) {
System.out.print(a + " ");
long c = a + b;
a = b;
b = c;
}
System.out.println();
}

There should be one more array element space for int fib[], thus the fib[count] could be stored.
import java.util.Scanner;
public class Fibonacci
{
public static void main(String[] args)
{
int count;
Scanner in = new Scanner(System.in);
System.out.println("Please enter number");
count = in.nextInt();
int[] fib = new int [count + 1];
fib[0] = 1;
fib[1] = 1;
for (int i=2; i <= count; i++)
{
fib[i] = fib[i-1] + fib[i-2];
}
for(int i = 0; i<= count; i++)
{
System.out.print(fib[i] + " ");
}
}
}

public class Fibonacci
{
private int [] fibArray;
public Fibonacci()
{
}
public void Fibonacci()
{
fibArray = new int[0];
}
public void setFibonnaci(int size)
{
fibArray = new int[size];
if(fibArray.length == 1)
{
fibArray [0] = 0;
}
else if(fibArray.length == 2)
{
fibArray[0] = 0;
fibArray[1] = 1;
fibArray[2] = 2;
}
else
{
fibArray[1] = 1;
fibArray[0] = 0;
for(int x = 2; x < fibArray.length; x++)
{
fibArray [x] = fibArray[x-1] + fibArray[x-2];
}
}
}
public int getSequence(int number)
{
if(number -1 < fibArray.length)
{
return fibArray[number - 1];
}
return -1;
}
//check the test case for getFibo
public String toString()
{
String output = "";
for (int x = 0; x < fibArray.length; x++)
{
output += x + " - " + fibArray[x];
}
return output;
}
}
Late response but new to site and just trying to help. This fib class works 100%

how to display two-dimensional array in rectangular output?

This is not homework. I am a beginner (novice) java programmer, trying to read and complete the exercises at the end of ivor horton's beginning java book.
Write a program to create a rectangular array containing a multiplication table from 1 X 1 to 12 X 12. Output the table as 13 columns with the numeric values right aligned in columns. (The first line of output will be the column headings, the first column with no heading, then the numbers 1-12 for the remaining columns. The first item in each of the succeeding lines is the row heading which ranges from 1-12.
NOTE: I have only learned about Arrays & Strings, Loops & Logic, data types, variables, and calculations. I have not learned about classes and their methods and etc......so no fancy stuff please. THANKS!
public class Chapter4Exercise2 {
public static void main(String[] args)
{
int[][] table = new int[12][12];
for(int i=0; i <= table.length-1; i++)
{
for (int j=0; j <= table[0].length-1; j++)
{
table[i][j] = (i + 1) * (j + 1);
if (table[i][j] < 10)
System.out.print(" " + table[i][j] + " ");
else
if (table[i][j] > 10 && table[i][j] < 100)
System.out.print(" " + table[i][j] + " ");
else
System.out.print(table[i][j] + " ");
}
System.out.println(" ");
}
}
}

As long as the numbers are less than 1000, try this:
As #Mr1158pm said:
public class Chapter4Exercise2 {
public static void main(String[] args) {
int tableSize = 10;
int[][] table = new int[tableSize][tableSize];
for(int i=0; i < table.length; i++) {
for (int j=0; j < table[i].length; j++) {
table[i][j] = (i+1)*(j+1);
if(table[i][j] < 10) //Where i*j < 10
System.out.print(" "+(table[i][j])+" ");
else if(table[i][j] < 100) //Where i*j < 100
System.out.print(" "+(table[i][j])+" ");
else //Where i*j < 1000
System.out.print(" "+(table[i][j])+" ");
}
System.out.println("");
}

I don't think that you have to declare an array data structure to print out this table.
Just use two nested for loops and do calcs in the loops.
Here is a working method that you can work on. Just need to fix column alignment, add space here and there.
FYI row<10?" "+row:row is a form on inline if statement. If you haven't seen it before google it. It's quite useful.
public static void main(String[] args) {
for(int row=0; row<13; row++)
{
for(int col=0; col<13; col++)
{
if(row==0) //ffirst row
{
if(col==0)
System.out.print(" ");
else
System.out.print(col<10?" "+col:" "+col);
}
else
{
if(col==0)
System.out.print(row<10?" "+row:row);
else
System.out.print(row*col<10?" "+(row*col):(row*col<100? " "+(row*col):" "+(row*col)));
}
}
System.out.println();
}
}

import java.util.Scanner;
public class Back {
public static void main(String[] args) {
Scanner a1 =new Scanner(System.in);
int row,col;
String ch;
System.out.println("Enter width of screen:");
row = a1.nextInt();
System.out.println("Enter height of screen:");
col = a1.nextInt();
System.out.println("Enter background character:");
ch =a1.next();
String twoD[][] = new String[row][col];
int i,j;
for(i=0;i<row;i++)
for(j=0;j<col;j++){
twoD[i][j] = ch;
}
for(i=0;i<row;i++){
for(j=0;j<col;j++)
System.out.print(twoD[i][j]+" ");
System.out.println();
}

int width = 10;
int height = 10;
int[][] table = new int[width][height];
for(int i = 0; i < width; i++) {
for(int j = 0; j < height; j++) {
System.out.print(" " + table[i][j] + " ");
}
System.out.println("");
}