Check If a Value is Present in an Array in Java

Given an array of integers and a key element, the task is to check whether the key is present in the array. If the key exists, return true; otherwise, return false.

Example:

Input: arr[] = [3, 5, 7, 2, 6, 10], key = 7
Output: Is 7 present in the array: true

Input: arr[] = [-1, 1, 5, 8], key = -2
Output: Is -2 present in the array: false 

1. Using Linear Search Method

In the Linear Search method, each element of the array is sequentially compared with the key until a match is found or the end of the array is reached.

Example:

Is 7 present in the array: true

Explanation:

• Create a method isElementPresent which return a boolean value and takes two parameters array (arr) and the element(key).
• Iterate each element of the array and check if the element is equal to the given key return true otherwise return false.

2. Using Binary Search Method

Binary Search efficiently finds an element in a sorted array by repeatedly dividing the search interval in half.

The built-in Arrays.binarySearch() method performs this operation in logarithmic time.

Syntax:

public static int binarySearch(data_type[] arr, data_type key)

Return Value: Returns the index of the key if found; otherwise, a negative value.

Parameters:

• array: The array to be searched.
• key: The value to be searched for.

Example:

Is 17 present in the array: false

3. Using List.contains() Method: 

The contains() method of the List interface checks if a specific element exists in a list. We can convert an array to a list using Arrays.asList().

Syntax:

public boolean contains(Object element)

Parameter: It takes a single parameter Object which to be searched in the given list.

Return Type: It return a boolean value, if the element is present in the list return true, otherwise return false.

Example:

Is 7 present in the array: true

4. Using Stream.anyMatch() Method 

The anyMatch() method checks whether any element in a stream matches the provided predicate. It short-circuits as soon as a match is found.

Syntax:

boolean anyMatch(Predicate<T> predicate)

Parameter: This method takes a single parameter predicate of type T which is a generic.

Return Types: This method return a boolean value, True if the element is present otherwise return false.

Example 1: Using IntStream.of()

Is 7 present in the array: true

Example 2: Using Arrays.stream() method to create Stream