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Storing digits of numbers in array

Hello fellow programmers !
I am a beginner with Java and i am looking for a method or a way maybe to store the digits of a 6 digit number entered by the user , in an int array.
For example :-
if the number is 675421.
then i want to store the digits in an array like :-
int[] array = new int[6];
int number = 675421
array[0] = 6;
array[1] = 7;
array[2] = 5;
array[3] = 4;
array[4] = 2;
array[5] = 1;
I want to do so so that i can work with the array to maybe sort or change the order or numbers in array. Thanks!

Here you go,
String temp = Integer.toString(number);
int[] num = new int[temp.length()];
for (int i = 0; i < temp.length(); i++){
num[i] = temp.charAt(i) - '0';
}
for (int i = 0; i < temp.length(); i++) {
System.out.println(num[i]);
}
Edit, after comment
Here, First, you are converting to your number to a string.
Then, take each char out of it(in the loop), subtract the ASCII value of 0 from each char to get the digit [ie, ASCII of 0 is 48, 1 is 49, ... ] (see ASCII table)

Do something like this:
String number = "123123";
int[] intArray = new int[number.length()];
for (int i = 0; i < number.length(); i++)
{
intArray[i] = Integer.parseInt(Character.toString(number.charAt(i)));
}
Hope this helps,
Jason.

Below is the recursive solution
public static void main(String[] args) {
int testNum = 675421;
List<Integer> digitList = new ArrayList<Integer>();
collectDigits(testNum, digitList);
Object[] resultArr = digitList.toArray();
int listSize = resultArr.length;
for (int listCount = 0; listCount < listSize; listCount++) {
System.out.println("result["+listCount+"] = "+resultArr[listCount]);
}
}
private static void collectDigits(int num, List<Integer> digits) {
if (num / 10 > 0) {
collectDigits(num / 10, digits);
}
digits.add(num % 10);
}

One way to do this would be to turn the original integer into a string.
Loop over the string, parsing each character back to an int, and place into the array. Here is an example:
int number = 123456;
String strNumber = number+"";
int[] array = new int[strNumber.length()];
int index = 0;
for(char c : strNumber.toCharArray()){
array[index++] = Integer.parseInt(c+"");
}
System.out.println(Arrays.toString(array));

Math solution, you can split the int number using this:
int[] array = new int[6];
int number = 675421;
array[0] = ((number/100000)%10);
array[1] = ((number/10000)%10);
array[2] = ((number/1000)%10);
array[3] = ((number/100)%10);
array[4] = ((number/10)%10);
array[5] = ((number/1)%10);
If the "number" has a variable length you can automate this, write a coment if you need help

Array out of bound in Java

I am trying to count the number of each character from a to z in a random array of chars of size 100.
import java.util.Random;
public class RandomChars {
public static void main(String[] args) {
Random r = new Random();
String chars= "abcdefghijklmnopqrtuvwxyz";
String[] countc = new String[26];
char[] charArray = new char[100];
for(int i = 1;i<=100;i++)
{
charArray[i-1]=chars.charAt(r.nextInt(chars.length()));
System.out.print(chars.charAt(r.nextInt(chars.length())));
if(i%20==0)
{
System.out.println("");
}
}
//System.out.println(charArray.length);
int m = 0;
int p=0;
for(int n = 0;n<100;n++)
{
char xx = chars.charAt(n);
m = 0;
p=0;
do
{
if(charArray[m]==xx)
{
p=p+1;
}
m=m+1;
}while(m<=charArray.length);
countc[n]=""+p+""+xx;
}
System.out.println("The count of each character is "+ countc);
}
}

> for(int n = 0;n<100;n++)
should be
for (int n =0; n<99; n++)
charArray = 0 to 99 (i-1), but subroutine below you are going 0 to 100 (int n)

do
{
/* ... */
}while(m<=charArray.length);
On the last iteration, m will be equal to charArray.length, so when you call charArray[m], it'll be out of bounds. Change it to while(m < charArray.length); instead.

Change this:
m<=charArray.length
To this:
m<charArray.length

char xx = chars.charAt(n); is getting called all the way up to 99 when chars.charAt() can take a max argument of 25. You need to fix your loop logic so that you check all 100 elements for each of the 26 possible characters, not the other way around.
EDIT: Same thing is happening on your do..while loop.

Firstly, your String chars is omitting the 's' so I've added it in and updated the code to work slightly differently.
After creating the charArray it iterates over each character 26 times (once for each letter). There's probably a much better way to do this but I'm not so hot on Java.
import java.util.Random;
import java.util.Arrays;
public class RandomChars {
public static void main(String[] args) {
Random r = new Random();
String chars= "abcdefghijklmnopqrstuvwxyz";//added the 's'?
String[] countc = new String[26];
char[] charArray = new char[100];
for(int i=0; i<100; i++){
charArray[i]=chars.charAt(r.nextInt(chars.length()));
System.out.print(charArray[i]);
if((i+1)%20==0){
System.out.println("");
}
}
for(int n=0; n<26; n++){//for each of the 26 chars
char xx = (char)chars.charAt(n);
int p=0;
for(int a=0; a<100; a++){//loop through the charArray and count the matches
if(charArray[a]==xx){
p++;
}
}
countc[n]=""+xx+":"+p;
}
System.out.println("The count of each character is "+Arrays.toString(countc));
}
}
http://runnable.com/VCRLPa-2kdoqq2dW/stackoverflow-com-questions-26042877-for-java

ArrayIndexOutOfBoundsException for my PrintList function and I have no idea why

I am writing a really simple program which automatically extends the array when the user reaches the limit of the current array.
The problem is that I am getting a java.lang.ArrayIndexOutOfBoundsException when I run my PrintList method and I really don't know why. It's working perfectly if I use a random number, which is bigger than the array (e.g. 500), but if I use
for (int i = 0; i < stringArray.length; i++)
or
for (int i = 0; i <= stringArray.length; i++)
I get a nasty exception. How do I deal with this and why am I getting it in the first place?
Thanks a lot for your help!
Here's the source code of my program:
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
int index = 0;
String[] randomString = new String[1];
while (index <= randomString.length) {
out.println("Enter your string");
String input = keyboard.next();
randomString[index] = input;
PrintArray(randomString);
index++;
if (index >= randomString.length) {
ExtendArray(randomString);
continue;
}
}
}
public static void ExtendArray(String[] stringArray) {
String[] secondArray = new String[stringArray.length * 2];
// Copy first array into second array
for (int i = 0; i < stringArray.length; i++) {
stringArray[i] = secondArray[i];
stringArray = secondArray;
}
}
public static void PrintArray(String[] stringArray) {
for (int i = 0; i < stringArray.length; i++) {
out.println(" " + stringArray[i]);
}
}

Java does not work in the methods you are trying to employ. Everything in Java is passed by value, unless it is a data point in an object. What you are trying to employ is a pass by reference, which is not possible in Java.
What you are trying to do is an already existing data structure called a Vector: http://docs.oracle.com/javase/7/docs/api/java/util/Vector.html
I would suggest doing this: (not sure if it will work properly, as my current PC doesn't have dev tools):
public static String[] ExtendArray(String[] stringArray) {
String[] secondArray = new String[stringArray.length * 2];
// Copy first array into second array
for (int i = 0; i < stringArray.length; i++) {
secondArray[i] = stringArray[i];
}
return secondArray;
}
then calling it like so in main:
randomString = ExtendArray(randomString);
Relating to vectors, this is how it works in a Vector class:
public void incrementCount(int count){
int increment = (count * 2);
Object newElementData [] = new Object[increment];
for(int i = 0; i < count; i++)
{
newElementData[i] = elementData[i];
}
elementData = new Object[increment];
elementData = newElementData;
}
In this case, elementData is the original array, newElementData is a temp array that acts to up the bounds.

You cant get error on your PrintArray method, you get the error on the line before!
randomString[index] = input;
Because if you do this
index <= randomString.length
The last iteration is out of bounds, String of length 10 has values on 0-9. You have to change the while cycle to
index < randomString.length
Also your ExtendArray method is NOT functional!

You are supposed to swap out the randomString array for a new array with double length. You create a new array and copy the contents of the old one to the new one, but don't do anything with the new array.
I suppose you want the ExtendArray method to return the new array, and set the randomString variable to be the new array.

You need to return your second array from ExtendArray function:
public static String[] ExtendArray(String[] stringArray) {
String[] secondArray = new String[stringArray.length * 2];
// Copy first array into second array
for (int i = 0; i <= stringArray.length; i++) {
stringArray[i] = secondArray[i];
}
return secondArray;
}
and in your main:
randomString = ExtendArray(randomString);
also your while condition should be:
while (index < randomString.length)

How do I take null spaces out of an array?

I have to make a program that takes duplicate characters from an input array and prints out a new array with all unique characters.
It all works. Except when characters are taken out, it leaves an empty box at the end of that new array.
public class Deleter {
public static void main (String[] args){
Scanner keyboard = new Scanner(System.in);
char[] initialInputArray = new char[15];
System.out.println("How many characters do you wish to enter?");
int size = keyboard.nextInt();
while ( size > initialInputArray.length ) {
System.out.println("Error. Enter smaller number.");
size = keyboard.nextInt();
}
if( initialInputArray.length <= 15) {
for ( int counter = 0; counter < size; counter++ ){
initialInputArray[counter] = keyboard.next().charAt(0);
}
{
}
}
deleteRepeats(initialInputArray, size);
//Comeback to print out array
{
for ( int helloWorld = 0 ; helloWorld < size ; helloWorld ++)
System.out.print( initialInputArray[helloWorld] );
}
}
//"deleteReapets" method begins, looking for repeated user inputs
public static char[] deleteRepeats (char[] methodArray, int sizeTwo) {
if (sizeTwo == 0)
return methodArray;
if (sizeTwo == 1)
return methodArray;
int uniqueCharacter = 1;
//Start at the second entered character.
for (int x = 1; x < sizeTwo; ++x) {
int y;
for (y = 0; y < uniqueCharacter; ++y) {
if (methodArray[x] == methodArray[y]) break; // break if we find duplicate.
}
if (y == uniqueCharacter) {
methodArray[uniqueCharacter] = methodArray[x]; // add
++uniqueCharacter; // increment uniqueCharacter...[0,uniqueCharacter) is still "unique char list"
}
}
while ( uniqueCharacter < sizeTwo ) {
methodArray[uniqueCharacter] = 0;
uniqueCharacter++;
}
return methodArray;
}
}

That empty box is the null characters that you added at the end of the array. You are printing them because you are not adjusting size according to the number of unique characters (which can be less than the input size). Since you aren't creating a new array, you don't need to return a char [] from deleteRepeats. Instead, you can return the number of unique characters. That way, the calling program knows how many to print.
If your assignment requires that deleteRepeats return a char[], then you should allocate a new array that has a length exactly equal to uniqueCharacter, copy the unique characters to it, and return that. The calling program can just print that new (and shorter) array, rather than printing the first size elements of the input.

Probably the easiest way would be to make a new array to the size of your array of chars and then copy all of the chars into that. The problem with arrays is that once they have been initialized they can't be re sized. If your are familiar with arrayLists I would recommend using them. But if not try something like this...
int count = 0;
for(int i = 0; i < initialInputArray.size; i++){
count++;
}
char[] newArray = new char[count];
for(int i = 0; i < count; i++){
newArray[i] = initialInputArray[i];
}

I would suggest using a HashSet to remove duplicates and wrapping your char to Character. Something like this:
public static Character[] deleteRepeats (char[] methodArray){
HashSet<Character> set = new HashSet<Character>();
for(int index = 0; index < methodArray.length; index++){
set.add(methodArray[index]);
}
return set.toArray(new Character[set.size()]);
}
So in your main method, what you would do is something like this:
Character[] charArray = deleteRepeats(methodArray);
for(int index = 0; index < charArray.length; index++){
System.out.println(charArray[index]);
}

Printing letters in 2D arrays? First letter not showing

I'm hoping someone can answer this so I'll try to explain this well.
My goal is to generate a MAXIMUM of 3 unique vowels (AEIOU) on a line of 5 squares. I have made 25 squares using a 2D array (board[][]), but I want to do the first line first. Picture it like this:
Now, my problem is, whenever I try to generate random letters in my squares, the first letter doesn't show. For example I have E and O, O would only show in my squares, and not E. It's printing in my console, but not in my GUI.
Also, sometimes DUPLICATES of letters are showing. I don't know how to fix this :|
Here are the codes I've done so far:
String board[][] = new String[5][5];
String alphabet = "AEIOU";
int numArray[] = new int[5]; //where I can store random indices of alphabet
int finalIndex = 0;
int random = (int) (Math.random()*3) + 1; //random number of vowels to be generated
//this loop covers everything
for(int ctr = 0; ctr < random; ctr++) {
while(ctr != finalIndex) { //checks if there are any duplicates
int rand = (int) (Math.random()*4); //random position for the letter
numArray[ctr] = rand;
while(numArray[ctr] != numArray[finalIndex]) {
finalIndex++;
}
}
//finds the position of the letter in alphabet and converts it to String
char character = alphabet.charAt(numArray[ctr]);
String s = String.valueOf(character);
System.out.println(s);
//loop for putting the letters to the 2D array
for(int i = 0; i < board.length; i++) {
int gen = (int) (Math.random()*4); //random square for letter
for(int j = 0; j <= gen; j++) {
if(i == 0 && j < 5) { //row 1
board[i][gen] = s;
}
}
}
}
I decided not to put my GUI code anymore just to make things simpler.

Sorry I couldn't read what you had, so i tried this myself...
int rows = 5;
Character [] vowels = {'A','E','I','O','U'};
Character [][] board = new Character [vowels.length][rows];
for(int row = 0;row<rows;row++){
ArrayList<Character> tempVowels = new ArrayList<Character>(Arrays.asList(vowels));
int numVowPerLine = (int)Math.floor(Math.random()*4);
for(int j = 0;j<numVowPerLine;j++){
do{
int pos = (int)Math.floor(Math.random()*5);
if(board[row][pos] == null){
int temp = (int)Math.floor(Math.random()*tempVowels.size());
board[row][pos] = tempVowels.get(temp);
tempVowels.remove(temp);
break;
}
}while(true);
}
}