In this tutorial, we will see **“How to find Missing Number in an Array using Java 8 Streams?”**

### Find missing number in an array in java 8 using streams

Java 8 – How to find missing number in an array using Streams? Click To Tweet

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | /** * Using Java 8, Find the missing number in an array * @author Deepak Verma * */ import java.util.Arrays; public class Find_Missing_Number_In_Array_Java8Stream_Example { public static void main(String args[]) { int[] arrayOfIntegers = {1, 2, 3, 4, 6, 7, 8, 9}; int maxValue = Arrays.stream(arrayOfIntegers).max().getAsInt(); int expectedSum = maxValue * (maxValue + 1) / 2; int actualSum = Arrays.stream(arrayOfIntegers).sum(); int missingNumber = expectedSum - actualSum; System.out.println("Missing number in the array is: " + missingNumber); } } |

**Output:**

1 | Missing number in the array is: 5 |

### Find missing number in an array in java 8 using streams

In the above code, we use the Java 8 `stream`

API and along with that, the `max`

and `sum`

methods to find the missing number in the provided array. The variable denotes by `expectedSum`

holds the sum of all numbers from 1 to the maximum value in the given array. While on the other hand, the variables denotes by `actualSum`

holds the sum of all numbers in the array. At last, the missing number is figured out by subtracting the actual sum value from the expected sum value.

### Find missing number in an array in java 8 using streams

Java 8 – How to find missing number in an array using Streams? Click To Tweet

**Do you like this Post? – then check my other helpful posts:**

- Convert a Stream to a List in Java 8
- Stream maptoint in Java 8 with examples
- Double the numbers of specified ArrayList using Streams
- Double the even / odd numbers of a specified ArrayList using Streams
- How to check if Number is Prime or not using Streams
- Retrieve Even/Odd Numbers within the Range using Java 8 Streams
- How to add/sum up the ArrayList integers using Java8 Streams
- Generate Prime Numbers in Java 8 using Streams
- Comparator example – Collections sort with/without Lambda in Java 8
- How to pass function as a parameter in a method in Java 8?
- Remove duplicates from ArrayList in Java 8
- ForEach examples for Map/List in Java 8

**Other Useful References:**

Very helpful content

Glad you find it helpful. Thank you.