Java converts long to int

Question

The following code:

 import java.util.*;

 public class HelloWorld{

 public static void main(String []args){

    Scanner s = new Scanner(System.in);
    
    long N = s.nextLong();
    long[] arr = new long[N];
    
    System.out.println(N);
    
 }
}

Getting this error:

HelloWorld.java:12: error: incompatible types: possible lossy conversion from long to int long[] arr = new long[N];

As far as I understand there is no int involved in the code, can anyone explain why this is happening and how to solve this issue?

Answer 1

The size of arrays in Java can not exceed the range of an int , so the size parameter for array creation is implicitly an int . Change N to an int .

From JLS 15.10.1 Array Creation Expression (emphasis mine):

Each dimension expression undergoes unary numeric promotion (§5.6.1). The promoted type must be int , or a compile-time error occurs.

Answer 2

Array subscripts and sizes in Java must always be int , so in this expression new long[N] the N is converted to int , and because long has wider range than int , it's a narrowing conversion which must be done explicitly: new long[(int) N] . Or just read N as int : int N = s.nextInt() .

Answer 3

long[] arr = new long[N];

In this line you are creating an array of size N, but array sizes in Java can only be integers, that's why it's reading N as an int, if your intent is creating an array of N size you should read N as an int

int N = s.nextInt();

Answer 4

The maximum length of an array in java is 2,147,483,647 (2^31 - 1) which is the maximum length of int. So implicitly an array can have maximum the value of an int. So it cannot accept a long number.