Add Groovy blogpost - Determine-datatype-of-an-object

Author: gauravkukade

_posts/groovy/2021-05-11-determine-a-datatype-in-groovy.md

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+---
+layout: post
+title: "Groovy: How To Determine The Datatype Of An Object?"
+author: gaurav
+categories: [Groovy]
+description: "In this quick tutorial, we will how can we determine the datatype of an object in Groovy."
+---
+
+## Introduction
+
+In this quick tutorial, we will see how we can determine the datatype of an object in Groovy.
+
+When you are writing a Groovy code, sometimes you need to check the datatype of an object.  Also, not following the proper naming convention may lead to object datatype confusion.
+
+We will see the best way to check the datatype of an object in groovy so that you can use it correctly in the code.
+
+## How To Determine The Datatype Of An Object In Groovy?
+
+To determine the class of an object, you can simply call the `getClass()` method on it.
+
+An example is given below.
+```groovy
+anObject.getClass()
+```
+let check the above line program.
+
+```groovy
+def names = ['Gaurav', 'Shubham', 'Nayan', 'Sudeep'];
+
+println names.getClass(); // prints 'class java.util.ArrayList'
+
+def blogname = '''coderolls''';
+
+println blogname.getClass(); // prints 'class java.lang.String'
+
+println blogname.getClass().name; // prints 'java.lang.String'
+```
+
+Output:
+```
+class java.util.ArrayList
+class java.lang.String
+java.lang.String
+```
+In the above program, we can see that the `names` is an `ArrayList`  and `blogname` is a `String` object.
+
+When we call the `getClass()` method on these objects it prints its respective datatype.
+
+In most of the cases you can use the `anObject.getClass()` as `anObject.class`. But if `anObject` is `Map` it will try to retrieve the value with key 'class'.  Because of this it is always recommended to use `anObject.getClass()` instead of `anObject.class`.
+
+If you want to check if an object implements a particular interface or extends a particular class (e.g. String, ArrayList, etc), you can use the `instanceof` keyword.
+
+For example,
+
+```groovy
+(anObject instanceof String)
+```
+
+Let's check above code in an example program
+
+```groovy
+def blogname = '''coderolls''';
+println (blogname instanceof String) // true
+println (blogname instanceof ArrayList) // false
+```
+Output: 
+```
+true
+false
+```
+
+In the above program, I have defined one String `blogname`. I have used the `instanceof` keyword to check if the `blogname` implements the `String` class and it prints `true`. It means the `blogname` is an instance of the `String` class.
+
+When I used the `instanceof` keyword to check if the `blogname` implements the `ArrayList` class and it prints `false`. It means the `blogname` is not an instance of the `ArrayList` class.
+
+## Conclusion
+
+In this tutorial, we have seen how we can determine the datatype of an object in Groovy.
+
+You can use the `getClass()` method to determine the class of an object.
+
+```groovy
+anObject.getClass()
+```
+
+Also, if you want to check if an object implements an Interface or Class, you can use the `instanceof` keyword.
+
+```groovy
+(anObject instanceof String)
+```
+That's it about checking the datatype of an object in Groovy. 
+
+If you know any other way to check the datatype of an object, please comment below to help the community. Thank you.
+
+### Related Articles
+
+- [Hello World In Groovy](https://coderolls.com/hello-world-in-groovy/)