How can I do binary search in java ArrayList?

Question

I am trying to make binary search in ArrayList, but the binarySearch method does not work for Long, as well as Double and Float. My code is ``` import java.util.*; public class BinarySearchInArrayList { public static void main(String[]args) { ArrayList<Long> ar = new ArrayList(); for(long l = 1;l<100000;l++) { ar.add(l); } System.out.println("arraylist: "+ar); System.out.println("Which number's index do you want to know? "); Scanner scan = new Scanner(System.in); int p = scan.nextInt(); int index = Collections.binarySearch(ar,p); System.out.println("number "+p+" has index "+index); } ``` When I use Integer instead of `Long`, it works fine, but I want to make it with `Long`. Can you help me, please?

Accepted Answer

```
int p = scan.nextInt();
int index = Collections.binarySearch(ar,p);
```

Above should be:

```
long index = Collections.binarySearch(ar,p);
long p = scan.nextLong();
```

How can I do binary search in java ArrayList<Long>?

Solution

Problem