Try running that again. Write something, save and exit the app. Then pop back in and you should find that the text persists. Success!

Managing notes

So far so good, but in reality most notepad apps should give their users the ability to save more than one note. For that, we’re going to need some kind of note select screen!

Right click somewhere in your hierarchy on the left and select New > Activity, then choose ‘Basic Activity’ again. We’re calling this one ‘NoteSelect’. Enter that into the Activity Name and then hit ‘Finish’.

This will generate your Java file, your content layout and your app layout. Open up the activity_note_select.xml file and we’re going to make some similar changes to last time. This time, we want our FAB to display a ‘newnote’ icon for creating new notes. There’s nothing already available that really satisfies our requirements, so make your own and drop it into your app’s ‘drawable’ folder. You can do this by navigating to the project directory, or right clicking on the folder on the left of Android Studio and selecting ‘Show in Explorer’. You should now be able to select it from the list as before – remember that file names in your resources need to be lower case.

We’re going to use a recycler view in order to display our notes, which makes life a little more complicated. The good news is that using recycler views has become easier since last time (when we built the gallery app). You no longer need to add the dependency to Gradle and now the view can be selected straight from the designer, nice!

So add your recycler view as usual to the notes_select_content.xml and give it the ID ‘notes’. The XML code should look like this:

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 app:layout_behavior="@string/appbar_scrolling_view_behavior"
 tools:context="com.example.rushd.notepad.NoteSelect"
 tools:layout_editor_absoluteX="0dp"
 tools:layout_editor_absoluteY="81dp"
 tools:showIn="@layout/activity_note_select">

<android.support.v7.widget.RecyclerView
 android:layout_width="0dp"
 android:layout_height="0dp"
 android:clipToPadding="false"
 android:gravity="top"
 tools:layout_editor_absoluteX="8dp"
 tools:layout_editor_absoluteY="8dp"
 tools:layout_constraintTop_creator="1"
 tools:layout_constraintRight_creator="1"
 tools:layout_constraintBottom_creator="1"
 android:layout_marginStart="8dp"
 app:layout_constraintBottom_toBottomOf="parent"
 android:layout_marginEnd="8dp"
 app:layout_constraintRight_toRightOf="parent"
 android:layout_marginTop="8dp"
 tools:layout_constraintLeft_creator="1"
 android:layout_marginBottom="8dp"
 app:layout_constraintLeft_toLeftOf="parent"
 app:layout_constraintTop_toTopOf="parent"
 android:layout_marginLeft="8dp"
 android:layout_marginRight="8dp"
 android:id="@+id/notes"/>
</android.support.constraint.ConstraintLayout>

Next, create a new Java class (we’re ignoring the new activity for now). This Java class is going to build our note object (quick primer on what an object is in programming) so we’ll call it NotesBuilder. Right click on the Java folder and select New > Java Class. Add the following code:

public class NotesBuilder {

private String title,
content;

public NotesBuilder() {
}

public NotesBuilder(String title, String content) {
this.title = title;
this.content = content;
}

public String getTitle() {
return title;
}

public String getContent() {
return content;
}
}
Now we need another new layout file, which is going to define the layout of each row in our recycler view. This will be called list_row.xml and you’ll create it by right clicking on the layout folder and then choose New > Layout resource file. Pick ‘Relative Layout’ in the next dialog that comes up. The great thing about recycler view is that you can be as elaborate here as you like and include images and all kinds of other views in each row. We just want something simple for now though, so it will look like this:


<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent">

<TextView
android:id="@+id/title"
android:textSize="16dp"
android:textStyle="bold"
android:layout_alignParentTop="true"
android:layout_width="match_parent"
android:layout_height="wrap_content" />

<TextView
android:id="@+id/content"
android:layout_below="@id/title"
android:layout_width="match_parent"
android:layout_height="wrap_content" />

</RelativeLayout>

Next we need to create an ‘adaptor’. Basically, an adaptor takes a data set and attaches it to the recycler view. This will be another new Java class and this one will be called ‘NotesAdapter’.

public class NotesAdapter extends RecyclerView.Adapter & lt;
NotesAdapter.MyViewHolder & gt; {

    private List & lt;
    NotesBuilder & gt;
    notesList;

    public class MyViewHolder extends RecyclerView.ViewHolder {
        public TextView title, content;

        public MyViewHolder(View view) {
            super(view);
            title = (TextView) view.findViewById(R.id.title);
            content = (TextView) view.findViewById(R.id.content);

        }
    }

    public NotesAdapter(List & lt; NotesBuilder & gt; notesList) {
        this.notesList = notesList;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.list_row, parent, false);

        return new MyViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        NotesBuilder note = notesList.get(position);
        holder.title.setText(note.getTitle());
        holder.content.setText(note.getContent());
    }

    @Override
    public int getItemCount() {
        return notesList.size();
    }
}

Now if you look over this code, you’ll see that it is going through a list called notesList that has been built with our NoteBuilder class. Now everything is in place, we just need to add the relevant code to the NoteSelect.java script. This will read as follows:

public class NoteSelect extends AppCompatActivity {

    private List & lt;
    NotesBuilder & gt;
    notesList = new ArrayList & lt; & gt;
    ();
    private NotesAdapter nAdapter;
    private RecyclerView notesRecycler;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_note_select);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
            }
        });

        notesRecycler = (RecyclerView) findViewById(R.id.notes);

        nAdapter = new NotesAdapter(notesList);
        RecyclerView.LayoutManager mLayoutManager =
            new LinearLayoutManager(getApplicationContext());
        notesRecycler.setLayoutManager(mLayoutManager);
        notesRecycler.setItemAnimator(new DefaultItemAnimator());
        notesRecycler.setAdapter(nAdapter);

        prepareNotes();

    }

    private void prepareNotes() {
        File directory;
        directory = getFilesDir();
        File[] files = directory.listFiles();
        String theFile;
        for (int f = 1; f & lt; = files.length; f++) {
            theFile = "Note" + f + ".txt";
            NotesBuilder note = new NotesBuilder(theFile, Open(theFile));
            notesList.add(note);
        }

    }

    public String Open(String fileName) {
        String content = "";
        try {
            InputStream in = openFileInput(fileName);
            if ( in != null) {
                InputStreamReader tmp = new InputStreamReader( in );
                BufferedReader reader = new BufferedReader(tmp);
                String str;
                StringBuilder buf = new StringBuilder();
                while ((str = reader.readLine()) != null) {
                    buf.append(str + "\n");
                } in .close();

                content = buf.toString();
            }
        } catch (java.io.FileNotFoundException e) {} catch (Throwable t) {
            Toast.makeText(this, "Exception: " + t.toString(), Toast.LENGTH_LONG).show();
        }

        return content;
    }
}

Intent myIntent = new Intent(MainActivity.this, NoteSelect.class);
MainActivity.this.startActivity(myIntent);