sharedpreferences in the first Activity, show only once?

Question

I’m developing an app in which you will have the first Activity greeting, and I want to show it only once, only when the app first opens.

In this case, I created a Activity calling a layout containing the textview and button, as soon as the user clicks on the button, will open the Activity main app, and then do not want to Activity greeting be shown more.

My layout (summarized):

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Saudação Aqui" />

<Button 
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="sendMessage"
android:text="Ok, entrar para Activity principal e não mostrar mais essa tela" />

Greeting activity:

Button button;

    public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
     button=(Button)findViewById(R.id.button1); 

    button.setOnClickListener(new View.OnClickListener() { 

    @Override 
    public void onClick(View v) { 
    // TODO Auto-generated method stub 

    Intent i = new Intent(getApplicationContext(),Activity Principal.class);
    startActivity(i); 
} 
}); 
}

Thank you very much!

Answer 1

First you implement a class to manage Sharedpreferences (by organization).

public class PreferencesManager {
    public static final String ENTERING_FIRST_TIME = "EnteringFirstTime";

    public static void storeInt(Context context, String key, int value) {
        SharedPreferences prefs = context.getSharedPreferences("MyPrefs", Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = prefs.edit();
        editor.putInt(key, value);
        editor.commit();
    }

    public static int getInt(Context context, String key, int defaultValue){
        return context.getSharedPreferences("MyPrefs", Context.MODE_PRIVATE).getInt(key, defaultValue);
    }
}

So when your app starts, you can check this way:

if(PreferencesManager.getInt(view, PreferencesManager.ENTERING_FIRST_TIME, 1) == 1){
    //Salva informação de que o usuário já entrou no app a primeira vez
    PreferencesManager.storeInt(view, PreferencesManager.ENTERING_FIRST_TIME, 0);
    //Exibe saudação
}
else{
    //Esconde saudação
}

The ideal is to read and write information in Sharedpreferences outside the UI thread, to prevent your application from being destroyed by ANR (Application Not Responding). ANR’s happen when your application processes something longer than allowed in the Main Thread (five seconds).

It may seem impossible for such a simple task to take more than five seconds.

You can prevent this by calling the second code block within a Asynctask.