Project 2: File Explorer for android

In this project I am building a file explorer library for android. As I was working on catcher it became obvious I would need a file picker and explorer solution. So I did a bit of looking on the web. I found three interesting projects that nearly did what I wanted. I put a few of them together to come up with a hybrid solution.

1. FilePickerLibrary this is a great project looks beautiful lots of functionality great work.
2. MaterialFilePicker this was really nice library, simple and the code was really clean. It is material so for now it has a modern android feel.
3. FileBrowserView this has a lot more functionality, it is a bit older but has all the stuff I want for this project.

So I spent the last couple of day merging these projects into a single hybrid. It is going pretty well but not finished yet. You can find the current version of this project here: File Explorer

This will be an android library project. It is not the first time I have needed a file explorer for android so I am sure I will reuse it going forward.

Some lessons learned during this

1. There is no wizard in Idea for a library project

I was a bit surprised here, I looked and tried a few things but really nothing worked. In the end I just copied another library project template and renamed the paths.

Make sure and include the app and library in you base settings.gradle

include ':app', ':library'

2. There is a simple way to include the library in your app for testing

Intellij actually prompted me to do this which I thought was pretty cool. To add it just add it as a compile option

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.1.1'
    compile 'com.android.support:design:23.1.1'
    compile project(':library')
}

3. You may have permissions issues initially during the project

I found that when I transferred the apk to the emulator my permissions were not automatically applied. This was rather inconvenient. So i had to manually apply them in the emulator using the system tool

Here is some code (Android M4 +) to fix that:

if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.READ_EXTERNAL_STORAGE)) {
    DialogInterface.OnClickListener dialogClickListener = new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            switch (which) {
                case DialogInterface.BUTTON_POSITIVE:
                    ActivityCompat.requestPermissions(FileExplorerActivity.this,
                            new String[]{Manifest.permission.READ_EXTERNAL_STORAGE,
                                    Manifest.permission.WRITE_EXTERNAL_STORAGE},
                            REQUEST_FOR_READ_EXTERNAL_STORAGE);
                    break;
                case DialogInterface.BUTTON_NEGATIVE:
                    setResult(RESULT_CANCELED);
                    finish();
                    break;
            }
        }
    };
    AlertDialog.Builder builder = new AlertDialog.Builder(FileExplorerActivity.this);
    builder.setTitle(R.string.file_picker_permission_rationale_dialog_title)
            .setMessage(R.string.file_picker_permission_rationale_dialog_content)
            .setPositiveButton("Yes", dialogClickListener)
            .setNegativeButton("No", dialogClickListener).show();

}

4. My downloads directory on the emulator was empty so I had to transfer file

I used the adb to push a file to the emulator:

adb push NOTICE.txt /storage/emulated/0/Download/test.txt