Searching Arrays in Java

Searching is the process of finding the position or existence of a specific element within an array.

It’s one of the most common operations you’ll perform when working with data in Java — whether you’re checking for a student ID, searching a product code, or finding a value in a list.

What Is Searching in Java?

When you have multiple elements stored in an array, searching helps you determine:

• Whether a specific element exists in the array
• The index (position) of that element
• Or, if not found — that the element doesn’t exist

Java provides both manual searching techniques and built-in search utilities for efficient lookups.

Types of Searching in Java

There are two primary types of search operations in arrays:

Let’s explore both step-by-step

1. Linear Search (Sequential Search)

Linear Search is the simplest search technique — it checks each element one by one until it finds the target value.

Example: Linear Search in Java

public class LinearSearchExample {
    public static void main(String[] args) {
        int[] numbers = {10, 25, 30, 45, 50};
        int key = 30;
        boolean found = false;

        for (int i = 0; i < numbers.length; i++) {
            if (numbers[i] == key) {
                System.out.println("Element found at index: " + i);
                found = true;
                break;
            }
        }

        if (!found)
            System.out.println("Element not found!");
    }
}

Output:

Element found at index: 2

Points to Remember:

• Works on unsorted arrays.
• Simple to implement but slow for large datasets.
• Time Complexity: O(n)
• Best Case: When element found early.
• Worst Case: When element not present.

2. Binary Search

Binary Search is a faster and more efficient searching algorithm — but it only works on sorted arrays.

It follows the Divide and Conquer approach:

1. Compare the target value with the middle element.
2. If equal → found.
3. If smaller → search left half.
4. If larger → search right half.

Example: Binary Search in Java

import java.util.Arrays;

public class BinarySearchExample {
    public static void main(String[] args) {
        int[] numbers = {10, 20, 30, 40, 50};
        int key = 40;

        int result = Arrays.binarySearch(numbers, key);

        if (result >= 0)
            System.out.println("Element found at index: " + result);
        else
            System.out.println("Element not found!");
    }
}

Output:

Element found at index: 3

Using Built-in Method: Arrays.binarySearch()

Java provides a ready-made method in the java.util.Arrays class.

Example:

import java.util.Arrays;

public class BuiltInBinarySearch {
    public static void main(String[] args) {
        int[] numbers = {3, 6, 9, 12, 15};
        int key = 12;

        int index = Arrays.binarySearch(numbers, key);

        if (index >= 0)
            System.out.println("Element found at index: " + index);
        else
            System.out.println("Element not found!");
    }
}

Output:

Element found at index: 3

Key Differences Between Linear and Binary Search

Real-World Example

Imagine a student database:

• Linear Search: Find a student by scanning every record.
• Binary Search: If roll numbers are sorted, directly jump to middle values to find faster.