Java find variable type

Mastering Java Variable Types: A Guide to Finding the Type of a Variable

Learn different methods to determine the type of a variable in Java. From `getClass().getSimpleName()` to `instanceof`, this guide will help you avoid common issues with checking variable types.

• Using getClass().getSimpleName() to Check Variable Type
• Using instanceof Operator to Check Variable Type
• Find the type of a variable in Java
• Using getClass().getName() to Check Variable Type
• Checking Primitive Data Types
• Using println() Method to Display Variable Type
• Other simple code samples for finding the type of a variable in Java
• Conclusion
• How to find a type of variable in Java?
• How do you check the type of a variable?
• How to find datatype of an object in Java?
• How to print variable type in Java?

As a developer, understanding how to find the type of a variable is an important part of programming in Java. There are several methods that can be used to determine the type of a variable in Java, and in this blog post, we will discuss the key points, important points, and helpful points related to finding the type of a variable in Java.

Using getClass().getSimpleName() to Check Variable Type

The getClass().getSimpleName() method can be used to determine the simple name of the class of an object. This method is useful for determining the type of a variable when the variable is an object.

The following code example shows how to use getClass().getSimpleName() to find the type of a variable:

Object obj = new String("Hello World"); System.out.println(obj.getClass().getSimpleName()); 

As you can see, the output displays the simple name of the class of the object, which in this case is “String”.

Using instanceof Operator to Check Variable Type

The instanceof operator can be used to check if an object is an instance of a particular class. This operator returns a boolean value.

The following code example shows how to use instanceof to find the type of a variable:

Object obj = new String("Hello World"); if (obj instanceof String)

As you can see, the output displays that the variable is a String.

Find the type of a variable in Java

Using getClass().getName() to Check Variable Type

The getClass().getName() method can be used to determine the fully qualified name of the class of an object. This method is useful for determining the type of a variable when the variable is an object.

The following code example shows how to use getClass().getName() to find the type of a variable:

Object obj = new String("Hello World"); System.out.println(obj.getClass().getName()); 

As you can see, the output displays the fully qualified name of the class of the object, which in this case is “java.lang.String”.

Checking Primitive Data Types

Primitive data types can be checked using their respective wrapper classes. For example, the Integer class can be used to determine if a variable is an integer .

The following code example shows how to check if a variable is an integer:

int i = 5; if (i instanceof Integer)

Compilation error: Incompatible conditional operand types int and Integer 

When it comes to primitive data types, we cannot use instanceof to check the type of a variable. Instead, we can compare the variable with the corresponding wrapper class using == .

The following code example shows how to check if a variable is an integer:

int i = 5; if (i == Integer.valueOf(i))

As you can see, the output displays that the variable is an integer.

Using println() Method to Display Variable Type

The println() method can be used to display the type of a variable. This method is useful for debugging purposes.

The following code example shows how to use println() to display the type of a variable:

Object obj = new String("Hello World"); System.out.println(obj.getClass().getSimpleName()); 

As you can see, the output displays the simple name of the class of the object, which in this case is “String”.

Other simple code samples for finding the type of a variable in Java

In Java , for example, check type of variable java code sample

In Java , get type of variable java code example

((Object) myVar).getClass().getName() //OR ((Object) myInt).getClass().getSimpleName()

Conclusion

In conclusion, there are several methods that can be used to find the type of a variable in Java. Some of these methods include getClass().getSimpleName() , instanceof , and getClass().getName() . It is important to understand the difference between primitive and object data types when checking variable types . Using the appropriate method for the situation and taking advantage of the benefits of static typing can help avoid common issues with checking variable types in java .

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Java find variable type

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How to Check Variable Type in Java

You may know that the variable gives named storage that programs can access. Every variable in Java has a unique type that specifies its memory size, the range of operations that can be performed on the variable, and the range of values stored in memory. To compute data, sometimes you need to check the data type of a variable because the logical operations are performed with the same type of variables.

This write-up will discuss the approaches for checking the type of variable in Java.

How to Check Variable Type in Java?

To check the type of variable, you can follow these methods:

Let’s understand these approaches one by one.

Method 1: Check Variable Type Using instanceof Operator

For checking variable type in Java, there is a feature called the “instanceOf” operator, which is used to check the type of a variable or object. It gives the boolean value to tell whether the variable belongs to the specified type or not.

Use the below-given syntax for checking the type of variable using the instanceof operator:

Here, “s” is the variable, and “String” is the predefined Java wrapper class. The “instanceof” operator checks whether the variable “s” is a String type variable or not.

First, we will declare a String type variable “s” and initialize a String value:

Now, check the type of the created variable using the “instanceof” operator and print out the resultant value on the console:

Output shows the boolean value “true” which means the variable “s” is a type of “String”:

Let’s get the name of the type where the variable belongs.

Method 2: Check Variable Type Using getClass() With getName() Method

There is another method for checking the type of variable using the “getClass()” method of the “Object” class with the “getName()” method. This method outputs the full name of the class with its package name.

Follow the given syntax for checking type of variable:

Here, “s” is the variable whose type needs to be checked.

Firstly, we will declare a String type variable “s” and initialize it a string “Welcome to LinuxHint”:

Print the name of the class with the package that the variable belongs using the “getClass().getName()” method in “System.out.println()”:

In the output, the “java.lang.String” indicates that the variable “s” belong to the “String” class of the “java.lang” package:

The above approach will give the class name with the package. However, if you want to get only the class name, follow the below-given section.

Method 3: Check Variable Type Using getClass() With getSimpleName() Method

For getting the exact name of the class without their package, you can use the “getClass().getSimpleName()” method. It prints the class name from where it belongs.

The below-given syntax is used for the checking type of variable in Java:

Here, the “s” is the variable whose type will be checked using the “getSimpleName()” method.

We will now consider the same String “s” created in the previous example and print out its class name as follows:

As you can see that the invoked method only returned the class name:

We have compiled different ways for checking variable type in Java.

Conclusion

For checking variable type in Java, you can use instanceof operator, getClass().getName() method and the getClass().getSimpleName() method. The getClass().getName() method outputs the name of the class with its package name, while the getSimpleName() method prints the exact name of the class where the variable belongs. Lastly, the instanceof operator displays a boolean value. In this write-up, we discussed the methods to check the type of variable in Java.

About the author

Farah Batool

I completed my master’s degree in computer science. I am an academic researcher and love to learn and write about new technologies. I am passionate about writing and sharing my experience with the world.

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Java typeof Operator

1. Get the Type of a Variable/Value in Java
2. Get the Type of Any Variable/Value in Java

This tutorial introduces how to get the data type of a variable or value in Java and lists some example codes to understand the topic.

In Java, to get type of a variable or a value, we can use getClass() method of Object class. This is the only way to do this, unlike JavaScript with the typeof() method to check type.

Since we used the getClass() method of Object class, it works with objects only, not primitives. If you want to get the type of primitives, then first convert them using the wrapper class. Let’s understand with some examples.

Get the Type of a Variable/Value in Java

In this example, we used getClass() to check the type of a variable. Since this variable is a string type, then we can directly call the method. See the example below.

Notice that the getClass() method returns a fully qualified class name, including a package name such as java.lang.String in our case.

public class SimpleTesting  public static void main(String[] args)  String msg = "Hello";  System.out.println(msg);  System.out.println("Type is: "+msg.getClass());  > > 

Hello Type is: class java.lang.String 

Get the Type of Any Variable/Value in Java

In the above example, we used a string variable and got its type similarly; we can also use another type of variable, and the method returns the desired result. See the example below.

In this example, we created two more variables, integer and character, apart from string and used the getClass() method.

package javaexample; public class SimpleTesting  public static void main(String[] args)  String msg = "Hello";  System.out.println(msg);  System.out.println("Type is: "+msg.getClass());  // Integer  Integer val = 20;  System.out.println(val);  System.out.println("Type is: "+val.getClass());  // Character  Character ch = 'G';  System.out.println(ch);  System.out.println("Type is: "+ch.getClass());  > > 

Hello Type is: class java.lang.String 20 Type is: class java.lang.Integer G Type is: class java.lang.Character 

The getClass() method returns a complete qualified name of the class, including the package name. If you wish to get only the type name, you can use the getSimpleName() method that returns a single string. See the example below.

package javaexample; public class SimpleTesting  public static void main(String[] args)  String msg = "Hello";  System.out.println(msg);  System.out.println("Type is: "+msg.getClass().getSimpleName());   // Integer  Integer val = 20;  System.out.println(val);  System.out.println("Type is: "+val.getClass().getSimpleName());   // Character  Character ch = 'G';  System.out.println(ch);  System.out.println("Type is: "+ch.getClass().getSimpleName());  > > 

Hello Type is: String 20 Type is: Integer G Type is: Character 

Related Article — Java Operator

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