split int value into separate digits

Question

I want to split my int value into digits. eg if the no. is 542, the result should be 5,4,2.

I have 2 options. 1) Convert int into String & then by using getCharArray(), i can have separate characters & then i will convert them back into int values.

2) Convert int into String, without converting it into char array, iterate it & get all digits.

Is there any other way to solve the problem. If not, which of the option will be fast?

Answer 1

List<Integer> digits(int i) {
    List<Integer> digits = new ArrayList<Integer>();
    while(i > 0) {
        digits.add(i % 10);
        i /= 10;
    }
    return digits;
}

Answer 2

Use the mod 10 rule...

 List<Integer> digits = new ArrayList<Integer>();
 while (n > 0) {
     digits.add(n%10);
     n/=10;
 }

Answer 3

int num = 542;

if (num<0) num=-num; // maybe you'd like to support negatives
List<Integer> digits = new LinkedList<Integer>();

while (num>0) {
    digits.add(0, num%10);
    num=num/10;
}

System.out.println(Arrays.toString(digits.toArray())); // [5, 4, 2]

Answer 4

除以十并得到余数，将它们放入你选择的集合/数组中，继续这样做，直到商为零，你所拥有的只是一个余数

Answer 5

You could use a Stack instead of an ArrayList if the ordering was a big issue. When popped the digits off the stack you would get them in the correct order, with the most significant digit first.

Answer 6

int digits(int i) {
    int num=0;
    while(i > 0) {
        num *= 10;
        num += i % 10;
        i /= 10;
    }
    return num;
} 

Answer 7

This will split the digits for you. Now put them into an array instead of printing them out and do whatever you want with the digits. If you want to add them, you could replace the System.out with something like sum += z; .

public class Splitter {
    public static int numLength(int n) {
        int length;        
        for (length = 1; n % Math.pow(10, length) != n; length++) {}        
        return length;
    }
    public static void splitNums(double x){
        double y, z, t = x;   

        for (int p = numLength((int)x)-1; p >= 1; p--){
             y = t % Math.pow(10, (numLength((int)(t))-1));
             z = ((t - y)/Math.pow(10, p));             
             t = t - (z * Math.pow(10, p)); 

             System.out.println(Math.abs((int)(z)));
        }   
        System.out.println(Math.abs((int)(t)));          
    }
}

Answer 8

This algorithm will split primitive "int" into single digits. It starts from the last digit up to the first one.

class IntegerSplitterDemo {

static boolean digitChoper(int num) {

    for(int i = 10; i <= Integer.MAX_VALUE; i *= 10  ) {

        //Starts from the last digit so it will display the int in reverse order
        int remainder = (i == 10) ? num % 10 : (num % i / (i /10));

        //You can store the remainder value into ArrayList
        System.out.print(remainder + " ");

        //stop iterating the loop
        if(num % i == num) { break; }       
    }
    System.out.println("");
    return true;
} 

public static void main(String[] args) {
    int[] num = {0, 371, 372, 678, 432, 569, 341, 371, 567, 2569874};
    for(int number : num) {
        digitChoper(number);
    }
} // end main

}