MohammadSamandari

public class MainActivity extends AppCompatActivity {
//    We Are going to download Web Content.
    //    1) we start by creating a new class.
    public class DownloadTask extends AsyncTask<String, Void, String> {
//    a class is a collection of methods and variables that we can use in our app.
//    AsyncTask: is a way of running our code on a different thread than the main thread.
//    so far we used onCreate method thread which known as ui thread. it is advised to run
//    any code that gets a bit of time on a different thread rather than the main thread.
//    so we are creating some code that will be run in background.
//    AsyncTask usually gets 3 parameter.

MohammadSamandari

    //  Defining a Media Player:
    MediaPlayer mediaPlayer;

    //  Giving the Media Player a sound to play
    mediaPlayer =MediaPlayer.create(this,R.raw.music);

    //  Getting lenght of file in media player.
    int musicLength = mediaPlayer.getDuration();

    //  getting the current position of sound while playing

MohammadSamandari

    //  Defining Audio Manager:
    AudioManager audioManager;
    
    //  Getting System Service of Audio Manager
    audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
    
    //  Getting the MaxVolume of Phone
    int maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
    
    //  Getting the Current Sound of Phone

MohammadSamandari

txtScore.setText(new DecimalFormat("00").format(noCorrectAnswer) +
                " / " +
                new DecimalFormat("00").format(noAllQuestions));

MohammadSamandari

    <style name="Theme.AppCompat.Light.NoActionBar.FullScreen" parent="@style/Theme.AppCompat.Light.NoActionBar">
        <item name="android:windowNoTitle">true</item>
        <item name="android:windowActionBar">false</item>
        <item name="android:windowFullscreen">true</item>
        <item name="android:windowContentOverlay">@null</item>
    </style>

MohammadSamandari

//  Defining the second activity for moving to.
Intent intent = new Intent(getApplicationContext(), SecondActivity.class);
//  putting and extra into an intent so that on the other activity could be recieved.
intent.putExtra("editText", editText.getText().toString());
//  Starting the second activity
startActivity(intent);

//  On the Second Activity: how te recieve the intent that opened this activity.
Intent intent=getIntent();
//  How to extract the extra that has been put in the intent before starting the activity.

MohammadSamandari

       /*
      Permanent Data Storage
        There are different ways of storing data on the app, the most simple one iscalled
        Shared Preferences.
            this is a way of storing just very simple short items of data like username or ideally
            a preference that user has choosen for the app.
            it is great for storing short information.
      */

        SharedPreferences sharedPreferences = this.getSharedPreferences("com.mohammadsamandari.sharedpreferences", Context.MODE_PRIVATE);

MohammadSamandari

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;


public class ObjectSerializer {

MohammadSamandari

        //  Shared Preferences With arraylist.
        //  We want to save an arraylist into a shared preferences.
        //  the thing is shared preferences is limited in the objects in can get. so we are going to go around it.
        //  To do this, we are going to do a process called Serilization which is essentially
        //  like converting a json to a string to save it like a string.
        //  to Do this, we are going to add a new class called, ObjectSerializer.
        SharedPreferences sharedPreferences1=this.getSharedPreferences("com.mohammadsamandari.sharedpreferences",Context.MODE_PRIVATE);
        ArrayList<String> friends=new ArrayList<>();
        friends.add("Monica");
        friends.add("Chandler");

MohammadSamandari

    //  For Creating a menu in android, we need to add a new file. and we need to customise
    //  MainActivity.java file.
    //  The new file is a xml layout file which only gives the layout for our menu
    //  We created a folder in res as menu an inside that created a menu resource file.
    //  We customise the xml file and added items for the menu.
    <menu xmlns:android="http://schemas.android.com/apk/res/android">
        <item
            android:id="@+id/settings"
            android:title="Setting"/>