Ways to Convert Integer or int to Long in Java

There are multiple ways in which you can convert a primitive int or an Integer object to a Long object,

Constructs a newly allocated Long object that represents the specified long argument.

public static void main(String[] args) {
      Integer i = 1000;
      Long l = new Long(integer);
      System.out.println(l);
}

Output: 1000

Note: It is better to avoid using this constructor as it has been deprecated as of Java 9, as it's rarely appropriate to use this constructor. The Java doc for this constructor says "The static factory valueOf(long) is generally a better choice, as it is likely to yield significantly better space and time performance."

This method is available since Java 1.5. It returns a Long instance representing the specified long (int goes through an implicit type casing) value.

    public static void main(String[] args) {

      Integer integer = 2000;
      Long long = Long.valueOf(integer);
      

    }

⚡️ Long.valueOf method caches values in the range -128 to 127, inclusive, and may cache other values outside of this range.

    public static void main(String[] args) {

      Integer integer = 3000;
      Long long = Long.valueOf(integer.longValue());
      

    }