I need to open a file based on its mime type

Question

I have the code to get the mime type. It seems to work. When I put mimeType in an if statement, I don't get the desired effect. Here are the snippets.

GET the mime type--

MimetypesFileTypeMap mimeTypesMap = new MimetypesFileTypeMap();
String mimeType = mimeTypesMap.getContentType(file);

Now I want to only open a file if the mime type is text--

if (file.isFile()) {
try {
    if (mimeType == "text/plain") openFile(file);
} catch (IOException e) {
    e.printStackTrace();
        System.err.print("    Cannot process file....\n");
}
}

This will not open a text file. Any ideas on why it will not work? openFile(file) works and is not the problem. file is a File Object. Thanks.

Answer 1

Maybe the mime type is just text?

MIME types file search order:

The MimetypesFileTypeMap looks in various places in the user's system for MIME types file entries. When requests are made to search for MIME types in the MimetypesFileTypeMap, it searches MIME types files in the following order:

1. Programmatically added entries to the MimetypesFileTypeMap instance.
2. The file .mime.types in the user's home directory.
3. The file /lib/mime.types.
4. The file or resource named META-INF/mime.types.
5. The file or resource named META-INF/mimetypes.default (usually found only in the activation.jar file).

Find this file and find out what mime type was specified for .txt files. Source: link

Answer 2

You're comparing the MIME type using ==, not String#equals() -- it's a String, yes? You probably have to do this:

if (mimeType.equals("text/plain")) openFile(file);

Or better still:

if ("text/plain".equals(mimeType)) openFile(file);

since that prevents a NPE from getting in your way.