How to search element in Integer Array using Binary Search in Java?

Declaration :

public static int binarySearch(int[] a, int key)

1	public static int binarySearch(int[] a, int key)

Explanation :

Purpose	The java.util.Arrays.binarySearch(int[] a int key) method searches the specified array of ints for the specified value using the binary search algorithm.The array must be sorted before making this call.If it is not sorted the results are undefined.
Parameters	a ===> This is the array to be searched.
	key ===> This is the value to be searched for.
Return Value	This method returns index of the search key if it is contained in the array else it returns (-(insertion point) - 1). The insertion point is the point at which the key would be inserted into the array: the index of the first element greater than the key or a.length if all elements in the array are less than the specified key.
Exception	NA

Java Program : Example

Below example will explain java.util.Arrays.binarySearch() method.

package com.c4learn;
import java.util.Arrays;
public class ArrayDemo {
 public static void main(String[] args) {
		    // Initialize unsorted int array
		    int arr[] = {35,25,5,15,45};
		    // Sorting array
		    Arrays.sort(arr);
		    // Printing sorted int array list
		    System.out.println("The sorted int array is:");
		    for (int num : arr) {
		      System.out.println("Array Element is " + num);
		    }
		    // Enter the value to be searched
		    int val = 25;
		    int retVal = Arrays.binarySearch(arr,val);
		    System.out.println("The index of element 25 is : " + retVal);
		  }
}

package com.c4learn;

import java.util.Arrays;

public class ArrayDemo {

public static void main(String[] args) {

// Initialize unsorted int array

int arr[] = {35,25,5,15,45};

// Sorting array

Arrays.sort(arr);

// Printing sorted int array list

System.out.println("The sorted int array is:");

for (int num : arr) {

System.out.println("Array Element is " + num);

}

// Enter the value to be searched

int val = 25;

int retVal = Arrays.binarySearch(arr,val);

System.out.println("The index of element 25 is : " + retVal);

}

Output of Program :

The sorted int array is:
Array Element is 5
Array Element is 15
Array Element is 25
Array Element is 35
Array Element is 45
The index of element 25 is : 2

The sorted int array is:

Array Element is 5

Array Element is 15

Array Element is 25

Array Element is 35

Array Element is 45

The index of element 25 is : 2

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