You could read the entire input line from scanner, then split the line by , then you have a String[], parse each number into int[] with index one to one matching...(assuming valid input and no NumberFormatExceptions) like

String line = scanner.nextLine();
String[] numberStrs = line.split(",");
int[] numbers = new int[numberStrs.length];
for(int i = 0;i < numberStrs.length;i++)
{
   // Note that this is assuming valid input
   // If you want to check then add a try/catch 
   // and another index for the numbers if to continue adding the others (see below)
   numbers[i] = Integer.parseInt(numberStrs[i]);
}

As YoYo's answer suggests, the above can be achieved more concisely in Java 8:

int[] numbers = Arrays.stream(line.split(",")).mapToInt(Integer::parseInt).toArray();  

To handle invalid input

You will need to consider what you want need to do in this case, do you want to know that there was bad input at that element or just skip it.

If you don't need to know about invalid input but just want to continue parsing the array you could do the following:

int index = 0;
for(int i = 0;i < numberStrs.length;i++)
{
    try
    {
        numbers[index] = Integer.parseInt(numberStrs[i]);
        index++;
    }
    catch (NumberFormatException nfe)
    {
        //Do nothing or you could print error if you want
    }
}
// Now there will be a number of 'invalid' elements 
// at the end which will need to be trimmed
numbers = Arrays.copyOf(numbers, index);

The reason we should trim the resulting array is that the invalid elements at the end of the int[] will be represented by a 0, these need to be removed in order to differentiate between a valid input value of 0.

Results in

Input: "2,5,6,bad,10"  
Output: [2,3,6,10]

If you need to know about invalid input later you could do the following:

Integer[] numbers = new Integer[numberStrs.length];
for(int i = 0;i < numberStrs.length;i++)        
{
    try 
    {
        numbers[i] = Integer.parseInt(numberStrs[i]);
    }
    catch (NumberFormatException nfe)   
    {
        numbers[i] = null;
    }
}

In this case bad input (not a valid integer) the element will be null.

Results in

Input: "2,5,6,bad,10"  
Output: [2,3,6,null,10]

You could potentially improve performance by not catching the exception (see this question for more on this) and use a different method to check for valid integers.

For example:

static int[] parseIntArray(String[] arr) {
    return Stream.of(arr).mapToInt(Integer::parseInt).toArray();
}

So take a Stream of the String[]. Use mapToInt to call Integer.parseInt for each element and convert to an int. Then simply call toArray on the resultant IntStream to return the array.

Suppose, for example, that we have a arrays of strings:

String[] strings = {"1", "2", "3"};

With Lambda Expressions ^{[1] [2]} (since Java 8), you can do the next ▼:

int[] array = Arrays.asList(strings).stream().mapToInt(Integer::parseInt).toArray();

▼ This is another way:

int[] array = Arrays.stream(strings).mapToInt(Integer::parseInt).toArray();

—————————
Notes
  1. Lambda Expressions in The Java Tutorials.
  2. Java SE 8: Lambda Quick Start

If you are using java 8 Try this :

 int[] array = Arrays.stream(resultsStr).mapToInt(Integer::parseInt).toArray();

If you are using Java8 than this is simple way to solve this issue.

List<?> list = Arrays.asList(indexNumber.split(" "));
list = list.stream().mapToInt(n -> Integer.parseInt((String) n)).boxed().collect(Collectors.toList());

In first Line you are taking a generic List Object and convert your array into list and than using stream api same list will be filled with equivalent Integer value.

First lets see why your attempt didn't work :

Arrays.stream(words).map(n -> n.length()).toArray(); 

The above statement returns Object[]. You could use .toArray(Integer[]::new); but then this would return Integer[]

Instead you can make use of mapToInt :

int[] array = Arrays.stream(words).mapToInt(String::length).toArray();

String arr = "[1,2]";
String[] items = arr.replaceAll("\\[", "").replaceAll("\\]", "").replaceAll("\\s", "").split(",");

int[] results = new int[items.length];

for (int i = 0; i < items.length; i++) {
    try {
        results[i] = Integer.parseInt(items[i]);
    } catch (NumberFormatException nfe) {
        //NOTE: write something here if you need to recover from formatting errors
    };
}

I'd split the string, stream the array, parse each element separately and collect them to an array:

int[] result = Arrays.stream(str.split(" ")).mapToInt(Integer::parseInt).toArray();