Java - convert int to long
xxxxxxxxxx// from intint number = 200;// 1. int to longlong result = (long) number;// 2. int to longlong result = 1L * number;// 3. int to LongLong result = Long.valueOf(number);// from IntegerInteger number = 200;// 1. Integer to longlong result = number.longValue();// 2. Integer to LongLong result = Long.valueOf(number);Below we have full examples of how to convert int to long.
xxxxxxxxxxpublic class Example1 { public static void main(String[] args) { int number = 200; long longNumber = (long) number; longNumber += 5L * Integer.MAX_VALUE; System.out.println(longNumber); // 10737418435 }}Output:
xxxxxxxxxx10737418435xxxxxxxxxxpublic class Example2 { public static void main(String[] args) { int number = 200; long longNumber = number; longNumber += 5L * Integer.MAX_VALUE; System.out.println(longNumber); // 10737418435 }}Output:
xxxxxxxxxx10737418435xxxxxxxxxxpublic class Example3 { public static void main(String[] args) { int number = 200; long longNumber = 1L * number; longNumber += 5L * Integer.MAX_VALUE; System.out.println(longNumber); // 10737418435 }}Output:
xxxxxxxxxx10737418435xxxxxxxxxxpublic class Example4 { public static void main(String[] args) { int number = 200; Long longNumber = new Long(number); longNumber += 5L * Integer.MAX_VALUE; System.out.println(longNumber); // 10737418435 }}Output:
xxxxxxxxxx10737418435Note:
Syntax of Long constructor:
public Long(long value)As we can see this constructor get long as parameter, so in our case we just made casting from int to long.
When we see the hint from intellij idea, we will see 'Remove boxing' and when we apply it, our code will convert
from:
Long longNumber = new Long(number);to:
Long longNumber = (long) number;When we use new Long constructor with int parameter we get hint from intellij idea:
Unnecessary boxing 'Long.valueOf(number)' less... (Ctrl+F1)
Inspection info: Reports explicit boxing, i.e. wrapping of primitive values in objects. Explicit manual boxing is unnecessary under Java 5 and newer, and can be safely removed.
This inspection only reports if the project or module is configured to use a language level of 5.0 or higher.
xxxxxxxxxxpublic class Example5 { public static void main(String[] args) { int number = 200; Long longNumber = Long.valueOf(number); longNumber += 5L * Integer.MAX_VALUE; System.out.println(longNumber); // 10737418435 }}Output:
xxxxxxxxxx10737418435Note:
The same hint from intellij idea as for Long constructor.Syntax of Long.valueOf() method:
public static Long valueOf(long l)Intellij idea, hint 'Remove boxing' will convert
from:
Long longNumber = Long.valueOf(number);to:
Long longNumber = (long) number;When we use Long.valueOf() we get hint from intellij idea:
Unnecessary boxing 'Long.valueOf(number)' less... (Ctrl+F1)
xxxxxxxxxxpublic class Example6 { public static void main(String[] args) { Integer number = 200; long longNumber = number.longValue(); longNumber += 5L * Integer.MAX_VALUE; System.out.println(longNumber); // 10737418435 }}Output:
xxxxxxxxxx10737418435
