How to search for a string in an ArrayList in java?

 How to search for a string in an ArrayList in java?

Do Check My Video On Utility Classes in java

Collection class defines the following binary search method

1)public static int binarySearch(List l,Object target):

if the list is sorted acc. default natural sorting order then we have to use this method

2)public static int binarySearch(List l,Object target,Comparator c):

we have to use this method if the list is sorted acc. to customized sorting

Conclusions:1)above method internally use binary search algorithm

2)Succesful search returns index

3)Unsuccesful search returns insertion point

4)insertion pt. is the location where we can place target elementin the sorted list

5)before calling the method the list Should be sorted otherwise we will gwt

unpredictable result

Note:if the list is sorted acc. to comparator object then at the time of

search we have to pass same comparator object

 

Example:

import java.util.Collections;

import java.util.Comparator;

import java.util.ArrayList;

public class Test{

    public static void main(String[] args) {

        ArrayList<String> l = new ArrayList<>();

        l.add("K");

        l.add("N");

        l.add("M");

        l.add("J");

        l.add("L");

        // l.add(new Integer(10));//CCE

        //l.add(null);//NPE

        System.out.println("Before Sorting: "+l);//[K, N, M, J, L]

        Collections.sort(l);

        System.out.println("After Sorting: "+l);//[J, K, L, M, N]

        System.out.println(Collections.binarySearch(l,"M"));//3

        System.out.println(Collections.binarySearch(l,"O"));//-6

        System.out.println(Collections.binarySearch(l,"A"));//-1

    }

}

o/p:

-1 -2 -3 -4 -5 

J  K   L  M  N

1  2   3  4  5