Java Program to Convert int to long - GeeksforGeeks

09 Feb, 2022
Given a number of int datatype in Java, your task is to write a Java program to convert this given int datatype into a long datatype.
Example:
Input: intnum = 5
Output: longnum = 5

Input: intnum = 56
Output: longnum = 56
Int is a smaller data type than long. Int is a 32-bit integer while long is a 64-bit integer. They both are primitive data types and the usage depends on how large the number is.
Java int can be converted to long in two simple ways:
Using a simple assignment. This is known as implicit type casting or type promotion, the compiler automatically converts smaller data types to larger data types.Using valueOf() method of the Long wrapper class in java which converts int to long.
Using a simple assignment. This is known as implicit type casting or type promotion, the compiler automatically converts smaller data types to larger data types.
Using valueOf() method of the Long wrapper class in java which converts int to long.
1. Implicit type casting: 
In this, we are simply assigning an integer data type to a long data type.
Since integer is a smaller data type compared to long, the compiler automatically converts int to long, this is known as Implicit type casting or type promotion.
Java
// Java program to demonstrate// use of implicit type casting  import java.io.*;import java.util.*;class GFG {    public static void main(String[] args)    {        int intnum = 5;          // Implicit type casting , automatic        // type conversion by compiler        long longnum = intnum;          // printin the data-type of longnum        System.out.println(            "Converted type : "            + ((Object)longnum).getClass().getName());          System.out.println("After converting into long:");        System.out.println(longnum);    }}
Converted type : java.lang.Long
After converting into long:
5
2.  Long.valueOf() method:
In this, we are converting int to long using the valueOf() method of the Long Wrapper class.
The valueOf() method accepts an integer as an argument and returns a long value after the conversion.
Java
// Java program to convert// int to long using valueOf() method  import java.io.*;  class GFG {    public static void main(String[] args)    {        int intnum = 56;        Long longnum = Long.valueOf(intnum);          // printing the datatype to        // show longnum is of type        // long contains data of intnum        System.out.println(            "Converted type : "            + ((Object)longnum).getClass().getName());          // accepts integer and        // returns a long value        System.out.println("After converting into long:"                           + "\n" + longnum);    }}
Converted type : java.lang.Long
After converting into long:
56
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