Java program for linear search an unsorted array?

Problem statement

Write a java program for linear search of an unsorted array. Run your program with a few testcases do demonstrate your program.

An unsorted or unordered array is an array where elements of the array are not sorted. To search for an element in this array, you have to scan the entire array to check if the element is present or not.

Flow Chart for linear search

 

Environment

Tools used to develop the program:

• JDK
• IntelliJ IDE

Java Program

import java.util.InputMismatchException;
import java.util.Scanner;

public class LinearSearch {

    public static void main(String[] args) {
        int n , index = -1;
        Scanner input = null;
        int[] a = null;
        try {
            input=new Scanner(System.in);
            System.out.println("Enter size of the array:");
            n= input.nextInt();

            if(n > 1) {
                a=new int[n];
                System.out.println("Enter array elements:");
                for (int i = 0; i < n; i++) {
                    a[i] = input.nextInt();
                }
            }else{
                //quit
                System.exit(0);
            }

            System.out.println("Input Array:");
            printArray(a);

            System.out.println("Enter the value to find:");
            int search_item= input.nextInt();

            for(int i=0;i<n;i++){
                if(search_item==a[i])
                {
                    index = i;
                    break;
                }
            }

            if(index == -1 ) {
                System.out.println("Search item not found in the array");
                System.exit(0);
            }
            else{
                System.out.println("Item found at position " + index +" 
marked with *:" );
                printArray(a,index);
            }

        }catch (InputMismatchException ime) {
            System.out.println("Not a valid input");
        }
        catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(input!=null)
            {input.close();}
        }
    }

    private static void printArray(int[] a){
        for (int anA : a) {
            System.out.print("[ " + anA + " ]");
        }
        System.out.println( "");
    }

    private static void printArray(int[] a, int index){
        for (int i=0;i< a.length;i++) {
            if(i == index)
                System.out.print("[* " + a[i] + "*]");
            else
                System.out.print("[ " + a[i] + " ]");
        }
        System.out.println( "");
    }
}

 

Run output

Save the program in the IDE. Execute the program and run the test cases.

Testcase

Enter size of the array:
7
Enter array elements:
23
56
89
99
156
1089
34
Input Array:
[ 23 ][ 56 ][ 89 ][ 99 ][ 156 ][ 1089 ][ 34 ]
Enter the value to find:
156
Item found at position 4 marked with *:
[ 23 ][ 56 ][ 89 ][ 99 ][* 156*][ 1089 ][ 34 ]

Testcase

Enter size of the array:
7
Enter array elements:
23
56
89
99
156
1089
34
Input Array:
[ 23 ][ 56 ][ 89 ][ 99 ][ 156 ][ 1089 ][ 34 ]
Enter the value to find:
1088
Search item not found in the array

Testcase

Enter size of the array:
-123
Enter positive number.

Testcase

Enter size of the array:
string
Not a valid input

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