TermuxFilePickerProvider: Small improvements

1. Return true from onCreate().
2. Implement getType().

app/src/main/java/com/termux/filepicker/TermuxFilePickerProvider.java

@@ -7,6 +7,7 @@
 import android.net.Uri;
 import android.os.ParcelFileDescriptor;
 import android.support.annotation.NonNull;
+import android.webkit.MimeTypeMap;
 
 import java.io.File;
 import java.io.FileNotFoundException;
@@ -15,7 +16,7 @@
 public class TermuxFilePickerProvider extends ContentProvider {
  @Override
  public boolean onCreate() {
- return false;
+ return true;
  }
 
  @Override
@@ -25,7 +26,20 @@ public Cursor query(@NonNull Uri uri, String[] projection, String selection, Str
 
  @Override
  public String getType(@NonNull Uri uri) {
- return null;
+ String contentType = null;
+ String path = uri.getPath();
+ int lastDotIndex = path.lastIndexOf('.');
+ String possibleFileExtension = path.substring(lastDotIndex + 1, path.length());
+ if (possibleFileExtension.contains("/")) {
+ // The dot was in the path, so not a file extension.
+ } else {
+ MimeTypeMap mimeTypes = MimeTypeMap.getSingleton();
+ // Lower casing makes it work with e.g. "JPG":
+ contentType = mimeTypes.getMimeTypeFromExtension(possibleFileExtension.toLowerCase());
+ }
+
+ if (contentType == null) contentType = "application/octet-stream";
+ return contentType;
  }
 
  @Override