How to go from an Activity "A" to an Activity "B" to select data and return to Activity "A" without the editText of Activity "A" being erased?

You should not regularly perform an Intent to "return" to an Activity unless you have implemented loading the data from a persistent source, such as a database or file.

What you want to do can be achieved by simply adding the onBackPressed() method to your Activity B:

@Override
public void onBackPressed() {
    super.onBackPressed();
    this.finish();
}

In this way, by clicking on the "back" button of your device, Activity B is closed and you return to Activity A, which was previously loaded and you do not have to reload it.

If you want to send data from Activity B to Activity A then you can do it using a bundle with the data and these are sent in a Intent , you can review this question:

Send data between activities

Send the data in the bundle and send it in Intent :

bundle.putString("Location", mList.get(position));
bundle.putInt("Type",3);
Intent intent = new Intent(mContext, ActivityA.class);
intent.putExtras(bundle);
mContext.startActivity(intent);

To receive them in Activity A, you can do it within the onCreate() method:

 Bundle parametros = this.getIntent().getExtras();

 String datos = "";
 int tipo = 0;
 if(parametros !=null){
    String datos = parametros.getString("Location"); 
    int tipo = parametros.getInt("Type"); 
 } 

and later these values can be added to your EditText , for example:

editTextDatos.setText(datos);
editTextDatos.setText(String.valueOf(tipo)); //* Los valores int debes convertirlos a String para usar el método setText()

You must save the status of your activity. use the method override SaveInstanceState and save all your data. In onCreate , if savedInstanceState is not null, restore all your data and set all the fields.

Android studio concept (Save the status of your activity): When your activity starts to stop, the system calls onSaveInstanceState () so that your activity can store the status information with a collection of key-value pairs. The default implementation of this method stores information about the status of the activity view hierarchy, such as text in an EditText widget or the scroll position of a ListView.

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {

    savedInstanceState.putInt("MY_FIELD", 43);
    // ... other fields


    super.onSaveInstanceState(savedInstanceState);
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState); // Always call the superclass first


    if (savedInstanceState != null) {

        int value = savedInstanceState.getInt("MY_FIELD");

        // ... update your views


    } else {
        // no previous state, start fresh
    }

}

More details: Here

Well after finding out more and thinking I found a solution a few days ago but I forgot to publish it I publish it for those who are ever in the same situation or a similar one What I did was very simple, the variables that I needed to capture a value in Activity B are declared as "public static" variables from Activity A, so that in this way I can change the values from Activity B (or any other activity ) and no longer depend on a Bundle to pass the data between Activitys, the next thing I did following Jorgesys' advice was to call the .finish () method; so that Activity B ends, returning to Activity A without losing any data from the editText and having changed the values of the variables that it needed. Below I leave an example in code:

Activity A:

public static int variableA;
public static String stringB;

Activity B:

import static  miProyecto.ActivityA.variableA;
import static  miProyecto.ActivityA.stringB;

/*clase y metodos...*/
.
.
.

variableA=3;
stringB="nuevo valor";
this.finish(); //o puedes utilizar el metodo onBackPressed();

It is worth emphasizing that to use the static variables you have to import them, after that their use is like that of a normal variable