Check file type, return url if image, else return file if pdf

Question

I have an API that returns the following:

"attachment": {
        "original": "......"
    }

This can be an image, a pdf, a word file, etc. Here are some examples:

"attachment": {
            "original": "/attachment/sample_pdf_file.pdf"
        }

"attachment": {
            "original": "/attachment/sample_image.jpg"
        }

// Etc.

My question is, how should I go about checking this and returning it to my adapter? If it's an image I want to use Picasso to upload the image, if it's a PDF then I want to use something else to show a pdf, and so on.

My thought process is that I should make a Model and a Util class for this.

So it would look something like this:

Model

public class Attachment {

    @SerializedName("original")
    private String mOriginal;
    public String getOriginal() { return mOriginal; }

}

Utility

public class AttachmentUtil {

    // Code to check stuff here

}

How should I go about checking this properly?

Answer 1

I'd fix the API to provide such information in returned data set:

"attachment": {
        "original": "/attachment/sample_pdf_file.pdf",
        "original_type": "pdf"
    }

"attachment": {
        "original": "/attachment/sample_image.jpg",
        "original_type": "jpg"
    }

but if you got no control over it, it most likely should be sufficient to check file name of your original. If so called "extension" is .pdf then it is PDF, if it is .jpg then it JPEG and so on. Or, cleaner way, use existing methods: guessContentTypeFromName() or guessContentTypeFromStream(). But again - fix the API if you can.