DSA using Java - Linear Search


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Overview

Linear search is a very simple search algorithm. In this type of search, a sequential search is made over all items one by one. Every items is checked and if a match founds then that particular item is returned otherwise search continues till the end of the data collection.

Algorithm

Linear Search ( A: array of item, n: total no. of items ,x: item to be searched)
Step 1: Set i to 1
Step 2: if i > n then go to step 7
Step 3: if A[i] = x then go to step 6
Step 4: Set i to i + 1
Step 5: Go to Step 2
Step 6: Print Element x Found at index i and go to step 8
Step 7: Print element not found
Step 8: Exit

Demo Program

package com.tutorialspoint.simplesearch;

import java.util.Arrays;

public class LinearSearchDemo {

public static void main(String args[]){
      // array of items on which linear search will be conducted. 
      int[] sourceArray = {1,2,3,4,6,7,9,11,12,14,15,
                           16,17,19,33,34,43,45,55,66,76,88};
      System.out.println("Input Array: " +Arrays.toString(sourceArray));
      printline(50);
      //find location of 1
      int location = find(sourceArray, 55);

      // if element was found 
      if(location != -1)
         System.out.println("Element found at location: " +(location+1));
      else
         System.out.println("Element not found.");

   }

   // this method makes a linear search. 
   public static int find(int[] intArray, int data){
      int comparisons = 0;
      int index= -1;

      // navigate through all items 
      for(int i=0;i<intArray.length;i++){
         // count the comparisons made 
         comparisons++;
         // if data found, break the loop 
         if(data == intArray[i]){
            index = i;
            break;
         }
      }
      System.out.println("Total comparisons made: " + comparisons);
      return index;
   }
   
   public static void printline(int count){
      for(int i=0;i <count-1;i++){
         System.out.print("=");
      }
         System.out.println("=");
   }
}

If we compile and run the above program then it would produce following result −

Input Array: [1, 2, 3, 4, 6, 7, 9, 11, 12, 14, 15, 16, 17, 19, 33, 34, 43, 45, 55, 66, 76, 88]
==================================================
Total comparisons made: 19
Element found at location: 19
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