Program 1 - Search an Element in an Array | Competitive Programming in C++

Given an array, the task is to write a Java program to check whether a specific element is present in this Array or not.

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Examples:

Input: arr[] = [5, 1, 1, 9, 7, 2, 6, 10], key = 7
Output: true

Input: arr[] = [-1, 1, 5, 8], key = -2
Output: false
An array is a data structure that contains a group of elements. Typically these elements are all of the same data type, such as an integer or string. Arrays are commonly used in computer programs to organize data so that a related set of values can be quickly sorted or searched. All the items of the array are stored at contiguous memory locations.

Approaches
There are numerous approaches to check whether a specific element is present in this Array or not in Java. These are –
Using the Linear Search method
Using the Binary Search method
Using List.contains() method
Using Stream.anyMatch() method
1. Using Linear Search Method:
In this, the list or array is traversed sequentially, and every element is checked.

2. Using Binary Search Method:
In this, search a sorted array by repeatedly dividing the search interval in half. Begin with an interval covering the whole array. If the value of the search key is less than the item in the middle of the interval, narrow the interval to the lower half. Otherwise, narrow it to the upper half. Repeatedly check until the value is found or the interval is empty.
In this example, the Arrays.binarySearch() method is used for Binary Search.
4. Using Stream.anyMatch() Method:
Stream anyMatch(Predicate predicate) returns whether any elements of this stream match the provided predicate. It may not evaluate the predicate on all elements if not necessary for determining the result.
Time Complexity: O(nlog(n))

Auxiliary Space: O(1)

3. Using List.contains() Method:
List contains() method in Java is used for checking if the specified element exists in the given list or not.