Java get file extension

In this post, we will see how to get extension of file in java.

As java.io.File does not provide any direct method for getting extension of file. This is used when you want to process file differently on the basis of its extension. I have worked on a project where I required this utility method.

There are two simple way to get it.

Using simple String handling program

Create a simple java class named GetExtensionOfFileMain.java

When you run above program, you will get following output:

File extension for Countries.xlsx is xlsx
File extension for Captial.csv is csv
File extension for src/main/resources is

As you can see, by using String’s contains() and lastIndexOf(), we are able to get extension of file in java.

Using Apache io

You need to download Apcahe io jar and put it to the classpath.
After doing above steps, you just need to call FilenameUtils.getExtension() to retrieve extension of file in java.

When you run above program, you will get foloowing output:

File extension for Countries.xlsx is xlsx
File extension for Captial.csv is csv
File extension for src/main/resources is

That’s all about java get file extension.

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