How to check data type in Java?

Sometimes, we need to check the data type of a variable to compute data because we can perform the logical operation with the same type of variables. In order to check the data type, we use getClass() and getSimpleName() method to get class and its name respectively. In this section, we will discuss how to check data type in Java?

Let's implement the code for getting data types of the variables. We first take input from the user, and then we find the data type of the variables in which user input will be stored.

CheckDataTypeExample.java

import java.util.*;
// create class CheckDataTypeExample to check the datatype of the variable
public class CheckDataTypeExample {
	// main() method start
	public static void main(String args[]) {
         		// declare variables
		int intData;
		char charData;
		
		// create Scanner class object to take input from user
		Scanner sc = new Scanner(System.in);
		
		// take input from the user to initialize variables
		
		System.out.println("Enter a String value:");
		String str = sc.nextLine();
		
		System.out.println("Enter Integer value:");
		intData = sc.nextInt();
        
		System.out.println("Enter Character value:");
		charData = sc.next().charAt(0);
		
		// close Scanner class object
		sc.close();
		
		// show datatypes of variables by using getClass() and getSimpleName() methods
		System.out.println(intData + " is of type " + ((Object)intData).getClass().getSimpleName());
		System.out.println(charData + " is of type " + ((Object)charData).getClass().getSimpleName());
		System.out.println(str + " is of type " + str.getClass().getSimpleName());
    }
}

Output:

Now, we have a special method, i.e., getType() provided by java.lang.reflect.Field and Character classes. Let's understand the getType() method of both classes one by one.

Field.getType()

The getType() method of the Field class is used to get the type of field defined by the Field object. The return value helps us in identifying the type of the field.

Syntax:

The syntax of the getType() method is as follows:

Parameter: It accepts no argument as a parameter.

Returns: It returns a class object that helps us in identifying the type of the field.

Let's take an example of the getType() method and understand how it works:

GetTypeExample1.java

// import required classes and package if any
import java.lang.reflect.Field;
 
// create class GetTypeExample1 to get the type of the Field
public class GetTypeExample1 {
  
 	// main() method start
 	public static void main(String[] args)throws Exception
     	{
  
        		//get the name field object by using getField() method
        		Field nameField = Student.class.getField("name");
  
        		// use getTyoe() method of the Field to get the type of name field
        		Class value = nameField.getType();
  
        		// print the type of name field
        		System.out.println("The type of the name field is " + value);
  
        		//get the totalMarks field object by using getField() method
        		Field marksField = Student.class.getField("totalMarks");
  
        		// use getTyoe() method of the Field to get the type of totalMarks field
        		value = marksField.getType();
  
        		// print the type of name field
        		System.out.println("The type of the totalMarks field is " + value);

 		//get the totalFees field object by using getField() method
        		Field feesField = Student.class.getField("totalFees");
  
        		// use getTyoe() method of the Field to get the type of name field
        		value = feesField.getType();
  
        		// print the type of the totalFees field
        		System.out.println("The type of the totalFees field is " + value);
    	}
}
  
// create a simple student class
class Student {
  
    	// declare and initialize variables
    	public static String name = "John";
 	public static double totalMarks = 380;
    	 public static float totalFees = 3413.99f;
  
    	// getter for student name
 	public static String getName()
     	{
        		return name;
    	}

 	// setter for student name
    	public static void setName(String stdName)
    	{
        		name = stdName;
    	}

// getter for totalMarks
 	public static double getTotalMarks()
    	{
        		return totalMarks;
    	}	

// setter for totalMarks
    	public static void setMarks(double marks)
    	{
        		totalMarks = marks;
    	}

// getter for totalFees
   	public static float getTotalFees()
    	{
        		return totalFees;
    	}

 	// setter for totalFees
   	public static void setFees(float fees)
    	{
        		totalFees = fees;
    	}	
}

Output:

Using Field.getType() Method

The getType() method of Character class is used to get general category of the given character. The getType() method comes with two variation based on the parameter, I.e., Character.getType(char ch) and Character.getType(int codePoint).

The getType() method that takes char as a parameter cannot handle the supplementary characters, whereas the getType() method that takes an int as a parameter can handle supplementary characters.

Syntax:

The getType() method of the Character class has the following syntax:

public static int getType(char ch)
public static int getType(int codePoint)

Parameter: The first variation of the getType() method accepts a parameter of type char and the second variation of the method accepts a parameter of type int, i.e., codePoint.

Returns: Both the methods return an integer value that indicates the general category of character.

Let's take an example of getType() method and understand how it works:

GetTypeExample2.java

// import required classes and package if any
// create class GetTypeExample2 to get the general category of the given character
public class GetTypeExample2 {
 	// main() method start
 	public static void main(String[] args)throws Exception
    	{
 		// use setter to set ch1, ch2 in CharData
 		CharData.setChar1('C');
 		CharData.setChar2('%');

  		// use getter to get char1 and char2
 		char char1 = CharData.getChar1();
 		char char2 = CharData.getChar2();

 		// use getType() method of Character class 
 		int val1 = Character.getType(char1);
 		int val2 = Character.getType(char2);

 		// print categories of char1 and char2
 		System.out.println("The category of " +char1 + " is "+ val1);
 		System.out.println("The category of " +char2 + " is "+ val2);
    	}
}
  
// create a simple CharData class
class CharData {
 	// declare variables of type char
 	static char ch1, ch2;
    	// getter for ch1
 	public static char getChar1()
    	{
        		return ch1;
    	}
 	// setter for ch1
    	public static void setChar1(char ch)
    	{
        		ch1 = ch;
    	}
 	// getter for ch2
 	public static char getChar2()
    	{
        	return ch2;
    	}
 	// setter for ch2
    	public static void setChar2(char ch)
    	{
        	ch2 = ch;
    	}
}

Output:

GetTypeExample3.java

// import required classes and package if any
import java.lang.reflect.Field;
// create class GetTypeExample3 to get the general category of the given character
public class GetTypeExample3 {
  	// main() method start
 	public static void main(String[] args)throws Exception
    	{
 		// use setter to set code1, code2 in CodePoint
 		CodePoint.setCodePoint1(0x0037);
 		CodePoint.setCodePoint2(0x016f);

 		// use getter to get code1 and code2
 		int code1 = CodePoint.getCodePoint1();
 		int code2 = CodePoint.getCodePoint2();

 		// use getType() method of Character class 
 		int val1 = Character.getType(code1);
 		int val2 = Character.getType(code2);

 		// print categories of char1 and char2
 		System.out.println("The category of " +code1+ " is "+ val1);
 		System.out.println("The category of " +code2+ " is "+ val2);
    	}
}
  
// create a simple CodePoint class
class CodePoint {
  
 	// declare variables of type int
 	static int codePoint1, codePoint2;

    	// getter for codePoint1
 	public static int getCodePoint1()
    	{
        		 return codePoint1;
    	}

// setter for codePoint1
   	public static void setCodePoint1(int code1)
    	{
        	 	codePoint1 = code1;
    	}

// getter for codePoint2
public static int getCodePoint2()
    	{
        	return codePoint2;
    	}

// setter for codePoint2
    	public static void setCodePoint2(int code2)
    	{
        		codePoint2 = code2;
    	}
}

Output: