From java. How to find a datatype of a variable at run time?

Question

there is a variable in java program. at run time I need to find the type of variable. can anyone put lights on this?

Answer 1

you can use instanceof, as in:

if (obj instanceof myclass) { ... }

But you have to be specify the classes or datatypes to test.

Answer 2

Using the code below, it'll tell you which type it is, including primitive types. This works out best because it doesn't return a boolean value and instead returns the actual data type name.

Syntax:
((Object)YOURVARIABLEHERE).getClass().getSimpleName()

https://code.sololearn.com/cnf9PQK7t1YW/#java

public class Program
{
public static void main(String[] args) {

String phrase = "Have a nice day!";
int number = 1;
float decimal = 1f;

System.out.print(phrase + " [");
System.out.println(((Object)phrase).getClass().getSimpleName() + "]");

System.out.print(number + " [");
System.out.println(((Object)number).getClass().getSimpleName() + "]");

System.out.print(decimal + " [");
System.out.println(((Object)decimal).getClass().getSimpleName() + "]");

}
}

// OUTPUT::::
Have a nice day! [String]
1 [Integer]
1.0 [Float]