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I am currently having an issue regarding combining a integer array into an integer.

I looked into a couple of other ways to do them at Way to combine integer array to a single integer variable?, but I still do not understand why I am running into errors.

My goal is to turn:

[6, 2, 3, 3, 8, 7, 7, 7, 0, 1, 6]



It currently works when given smaller integer arrays such as:

[1, 3, 4, 4]
-> 1344

It starts breaking down once the number of elements reaches 10. Does anybody have a possible solution?

You are overflowing the integer's maximum size of 2147483647. One way to address this is to use a BigInteger instead of an int:

BigInteger bigInt = BigInteger.ZERO;
for (int i : ints) {
    bigInt = bigInt.multiply(BigInteger.TEN).add(BigInteger.valueOf(i));

Java Iterator with examples, However since we type casted the integer value to String in the while loop, we got ClassCastException. Use Generics: Here we are using Generics so we didn't​  Iterators in Java Iterators are used in Collection framework in Java to retrieve elements one by one. There are three iterators.

We need to see the Error message to be sure but my first guess will be that you reach the size limit of int (2,147,483,647).

Integer iteration Help java, Integer iteration Help java. java iterator java iterator implementation example iterable java how to iterate object in java iterator array java iterator<integer java By using this iterator object, you can access each element in the collection, one element at a time. In general, to use an iterator to cycle through the contents of a collection, follow these steps − Obtain an iterator to the start of the collection by calling the collection's iterator( ) method. Set up a loop that makes a call to hasNext( ).

Well one possible way to solve this, I am assuming all integers are positive.

You can concatenate all integer array values into a String and form a single string.

So, [6, 2, 3, 3, 8, 7, 7, 7, 0, 1, 6] becomes 62338777016 (String).

BigInteger has a constructor (

That you can leverage, to get a BigInteger representation of the value.

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Here you are trying to use a integer for more than 10 digits which exceeds maximum value of 2,147,483,647, so you could use the below code which make minor changes like using a double.

  Integer[] arr = new Integer[] { 6, 2, 3, 3, 8, 7, 7, 7, 0, 1, 6 };
    Double myData = 0d;
    for (int i = 0; i < arr.length; i++) {
        double productfactor = (Math.pow(10, (arr.length-1-i)));
        myData = myData+arr[i]*productfactor;
    String formatted = new BigDecimal(Double.valueOf(myData)).toString();

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public static long convert(int[] arr) {
    long res = 0;

    for (int digit : arr) {
        // negative value is marker of long overflow
        if (digit < 0 || res * 10 + digit < 0)
            throw new NumberFormatException();
        res = res * 10 + digit;

    return res;

This is not an universal method, because of Long.MAX_VALUE. Otherwize, you have to use BigInteger isntead of long.

public static BigInteger convert(int[] arr) {
    // reserve required space for internal array
    StringBuilder buf = new StringBuilder(arr.length);

    for (int digit : arr)

    // create it only once
    return new BigInteger(buf.toString());

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Get an Iterator over a primitive array in Java, In this post, we will see how to get an iterator over a primitive array in Java. The iterator OfLong which are nothing but Iterator specialized for int, double and long values respectively. These can be Refer us to your friends and help us grow. How to iterate through Java List? This tutorial demonstrates the use of ArrayList, Iterator and a List. There are 7 ways you can iterate through List. Simple For loop; Enhanced For loop; Iterator; ListIterator; While loop; Iterable.forEach() util; Stream.forEach() util; Java Example: You need JDK 13 to run below program as point-5 above uses stream() util.

15 ways to Iterate through Stack in Java, In this post, we will discuss various methods to iterate through Stack in Java. Before we begin, we @Deprecated. Enumeration<Integer> enumeration = new Vector(stack).elements(); Refer us to your friends and help us grow. Stay Safe. 1) Iterators allow the caller to remove elements from the underlying collection during the iteration with well-defined semantics. 2) Method names have been improved. hashNext () method of iterator replaced hasMoreElements () method of enumeration, similarly next () replaced nextElement ().

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  • If your number is larger than Integer.MAX_VALUE, you'll have to use either Long or BigInteger.
  • MAX_INT = 2147483647
  • I can work with longs, but if I use bigInteger how would I go about it?
  • You are breaching the max integer limit. Hence, you are seeing your solution breaking. As Eran suggests, use a better datatype, which supports wider range.
  • can someone give me an example regarding how to use BigIntegers in this case? I've read a little about BigIntegers and it seems that they constrict too many functions
  • Shouldn't this be a reverse iteration?
  • @HimanshuBhardwaj no. OP wants the first element of the array to represent the left-most digit on the result.
  • @Mureinik does this program directly make 62338777016 out of the int array? I am confused as I have never used Big Integer
  • @chimmichanngas pretty much. You can think of a BigInteger as a really really large int that just uses methods like multiply and add instead of operators like * and +.
  • This is not good for performance because of multiple BigInteger instances to be created.
  • [6, 2, 3, 3, 8, 7, 7, 7, 0, 1, 6] 2147483647 [2, 3, 3, 8, 7, 7, 7, 0, 1, 6, 5] 2147483647 [3, 3, 8, 7, 7, 7, 0, 1, 6, 5, 3] 2147483647 [3, 8, 7, 7, 7, 0, 1, 6, 5, 3, 8] 2147483647 [8, 7, 7, 7, 0, 1, 6, 5, 3, 8, 8] 2147483647 [7, 7, 7, 0, 1, 6, 5, 3, 8, 8, 7] 2147483647 [7, 7, 0, 1, 6, 5, 3, 8, 8, 7, 3] 2147483647 [7, 0, 1, 6, 5, 3, 8, 8, 7, 3, 4] 2147483647
  • The array is the integer array and the number next to it is the combined element number
  • You can use long or BigInteger but more important is that you check the size of the array and validate that you are not overflowing