Store User Data Using Simple Text Files and APIs in Android

Creating the UI of the File Store App

Lets start by creating a simple app that shows an text editor and allows the user can input any text to be saved as a file.The saved text will be saved within the text editor next time the application is started by reading from the storage file.
First, we’ll create the UI for the app. Within the UI we are going to create a text editor and a save button on screen.
The layout for this UI is as follows:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Enter the text"
/>
<EditText
android:id="@+id/textbox"
android:singleLine="false"
android:gravity="top"
android:lines="10"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
<Button android:id="@+id/save"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Save the notes"
android:onClick="saveClicked"/>
</LinearLayout>






Above, we create a text view using the tag <TextView>, which just displays the text as “Enter The Text”.

Next, we create an editor to take in the text from the user. We create this using the <EditText> tag, and because we want the text to be multi-line, we also set the properties android:singleLine=“false” and android:lines=“10″ on the EditText. Then, we create a button using the <Button> tag, which will be used to save the modified text to a file.

Once the layout is created, we’ll use the function onCreate to set this layout of the content view as follows:

public class FileDemo extends Activity {
/** Called when the activity is first created. */
private final static String STORETEXT="storetext.txt";
private EditText txtEditor;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
txtEditor=(EditText)findViewById(R.id.textbox);
}
}
 

Now, if we run the app, the UI will look as follows:

Saving the File

Once the UI is done, we need to add functionality to save the text contents to a file upon pressing the “Save” button. To do this, the code is as follows:

public void saveClicked(View v) {
try {
OutputStreamWriter out=
new OutputStreamWriter(openFileOutput(STORETEXT, 0));
out.write(txtEditor.getText().toString());
out.close();
Toast
.makeText(this, "The contents are saved in the file.", Toast.LENGTH_LONG)
.show();
}
catch (Throwable t) {
Toast
.makeText(this, "Exception: "+t.toString(), Toast.LENGTH_LONG)
.show();
}
}
 

Once “Save” is clicked, the function saveClicked is called. In the function saveClicked, we open a file using the Android API openFileOutput by passing it the name of the file to open, which we defined in our class as

private final static String STORETEXT="storetext.txt";

Then, we create an object of OutputStreamWriter using the output of openFileOutput.

Finally, we get the text of the text editor and pass it to the write method of our OutputStreamWriter to write it to the file. Once the text is written to the file, we show a Toast to indicate that the text is saved. Below, the Toast reads “The contents are saved in the file.”

Reading the Text File Upon App Load

Now, let’s write a function that reads this newly-created file and populates the text editor with the contents of the file. We will call this function in the onCreate function so that as soon as the app launches, the editor is filled with the information from the file. The function is as follows:

public void readFileInEditor()
{
try {
InputStream in = openFileInput(STORETEXT);
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();
txtEditor.setText(buf.toString());
}
}
catch (java.io.FileNotFoundException e) {
// that's OK, we probably haven't created it yet
}
catch (Throwable t) {
Toast
.makeText(this, "Exception: "+t.toString(), Toast.LENGTH_LONG)
.show();
}
}

In this function, we first open the file with the API openFileInput, and then we create an InputStream from it. From that, we create an InputStreamReader and a BufferedReader. Using the BufferedReader, we read line after line the text of the storage file, and we store the text in the buffer. Once the whole file is read, we send the text into the editor. Now, if the application is run, the application will load the the editor filed with the contents of the file, as shown below.