dependencies {
  compile 'com.github.isabsent:filepicker:1.1.01'
}

<dependency>
  <groupId>com.github.isabsent</groupId>
  <artifactId>filepicker</artifactId>
  <version>1.1.01</version>
  <type>pom</type>
</dependency>

    FILE_ONLY_SINGLE_CHOICE
    FILE_ONLY_MULTI_CHOICE
    FILE_ONLY_DIRECT_CHOICE_IMMEDIATE
    FILE_ONLY_DIRECT_CHOICE_SELECTION

    FOLDER_ONLY_SINGLE_CHOICE
    FOLDER_ONLY_MULTI_CHOICE
    FOLDER_ONLY_DIRECT_CHOICE_IMMEDIATE
    FOLDER_ONLY_DIRECT_CHOICE_SELECTION

    FILE_OR_FOLDER_SINGLE_CHOICE
    FILE_AND_FOLDER_MULTI_CHOICE
    FILE_OR_FOLDER_DIRECT_CHOICE_IMMEDIATE
    FILE_OR_FOLDER_DIRECT_CHOICE_SELECTION

@Override
public void showListItemDialog(int titleResId, String folderPath, SimpleFilePickerDialog.CompositeMode mode, String dialogTag){
    SimpleFilePickerDialog.build(folderPath, mode)
            .title(titleResId)
            .show(this, dialogTag);
}

@Override
public void showListItemDialog(String title, String folderPath, SimpleFilePickerDialog.CompositeMode mode, String dialogTag){
    SimpleFilePickerDialog.build(folderPath, mode)
            .title(title)
            .show(this, dialogTag);
}

@Override
public boolean onResult(@NonNull String dialogTag, int which, @NonNull Bundle extras) {
    switch (dialogTag) {
        case PICK_DIALOG:
            if (extras.containsKey(SimpleFilePickerDialog.SELECTED_SINGLE_PATH)) 
         //Do what you want with single selection  
            else if (extras.containsKey(SimpleFilePickerDialog.SELECTED_PATHS))
         //Do what you want with multiple selection   
            break;
    }
    return false;
}