MainActivity.java

package com.israilbony.notepad;

import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class MainActivity extends Activity {

    TextView readingView;
    TextView appRestartsView;

    private int howManyTimesBeenRun = 0;
    private static final String NUMBER_OF_TIMES_RUN_KEY = "NUMBER";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_persistence);
        readingView = (TextView) findViewById(R.id.displayView);
        appRestartsView = (TextView) findViewById(R.id.applicationRestarts);
        SharedPreferences sharedPreferences=getPreferences(Context.MODE_PRIVATE);
        int defaultValue = 0;
        howManyTimesBeenRun = sharedPreferences.getInt(NUMBER_OF_TIMES_RUN_KEY,0);
        if (howManyTimesBeenRun == 0)
        {
            Toast.makeText(this, "Welcome to your new magic notepad!", Toast.LENGTH_LONG).show();
        }
        howManyTimesBeenRun++;
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putInt(NUMBER_OF_TIMES_RUN_KEY,howManyTimesBeenRun);
        editor.commit();
        appRestartsView.setText(String.valueOf(howManyTimesBeenRun));
    }


    @Override
    protected void onResume() {
        super.onResume();
        readingView.setText(getTextFile());
    }

    @Override
    protected void onPause() {
        saveTextFile(readingView.getText().toString());
        super.onPause();
    }
//Reading and Writing

    private static final String DATA_FILE = "my_file";
    public String getTextFile() {
        FileInputStream fileInputStream = null;
        String fileData = null;
        try
        {
            fileInputStream = openFileInput(DATA_FILE);
            int size = fileInputStream.available();
            byte[] buffer = new byte[size];
            fileInputStream.read(buffer);
            fileInputStream.close();
            fileData = new String(buffer, "UTF-8");
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return fileData;

    }

    public void saveTextFile(String content) {
        FileOutputStream fileOutputStream = null;
        try
        {
            fileOutputStream = openFileOutput(DATA_FILE,Context.MODE_PRIVATE);
            fileOutputStream.write(content.getBytes());
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        finally
        {

            try
            {
                if
                        (fileOutputStream != null)
                {
                    fileOutputStream.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.persistence, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

}