Get the extension from a MimeType

Question

I want to get the extension from a MimeType.

For example:

video/mp4                       ---->  mp4
application/x         


        

Answer 1

Using the suggestion of "Mindaugas Bernatavičius", I created a class to resolve my problem.

---

import java.util.HashMap;

public class MimeTypesAndExtensions {

    static HashMap MimesExtensions_HashMap = new HashMap();

    public MimeTypesAndExtensions() {
        super();
    }

    static {
        createHashMap();
    }

    /*****************************************************************************
     Extracted from : https://www.freeformatter.com/mime-types-list.html

     - The "x-" prefix of a MIME subtype simply means that it's non-standard,
       i.e. not registered with the "Internet Assigned Numbers Authority" (IANA).
     - The "vnd" prefix means that the MIME value is vendor specific.
    *****************************************************************************/
    private static void createHashMap() {

        // This list is not complete... 
        // I got it from https://www.freeformatter.com/mime-types-list.html
        MimesExtensions_HashMap.put("application/vnd.hzn-3d-crossword", "x3d");
        MimesExtensions_HashMap.put("application/vnd.lotus-1-2-3", "123");
        MimesExtensions_HashMap.put("text/vnd.in3d.3dml", "3dml");
        MimesExtensions_HashMap.put("video/3gpp2", "3g2");
        .....       
        MimesExtensions_HashMap.put("application/yin+xml", "yin");
        MimesExtensions_HashMap.put("application/vnd.zzazz.deck+xml", "zaz");
        MimesExtensions_HashMap.put("application/zip", "zip");
        MimesExtensions_HashMap.put("application/vnd.zul", "zir");
        MimesExtensions_HashMap.put("application/vnd.handheld-entertainment+xml", "zmm");
        MimesExtensions_HashMap.put("application/andrew-inset", "N/A");
    }

    public static String getExtensionFromMimeType(String mimeType) {

        String extension = "Extension Not Found";
        for(String key: MimesExtensions_HashMap.keySet()){
            if(key.toLowerCase().equals(mimeType.toLowerCase())) {
                extension = MimesExtensions_HashMap.get(key);
                return extension;
            }
        }

        return extension;
    }

    public static String getMimeTypeFromExtension(String extension) {

        StringBuilder mimeTypes = new StringBuilder();
        for(String key: MimesExtensions_HashMap.keySet()){
            if(MimesExtensions_HashMap.get(key.toLowerCase()).equals(extension.toLowerCase())) {
                mimeTypes.append(key.concat("\n"));
            }
        }

        if(mimeTypes.length() == 0)
            return "MimeType Not Found";

        return mimeTypes.toString();
    }

    public static String getMimeTypesAndExtensions(){

        StringBuilder mimeTypesAndExtensions = new StringBuilder();
        for(String key: MimesExtensions_HashMap.keySet()){
            mimeTypesAndExtensions.append(MimesExtensions_HashMap.get(key).concat("   ----->   ").concat(key).concat("\n"));
        }

        return mimeTypesAndExtensions.toString();
    }
}