MainActivity

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private EditText et_name,et_surname,et_email;
    private  static final String KEY_NAME = "NOMBRE";
    private  static final String KEY_SURNAME = "NOMBRE";
    private  static final String KEY_EMAIL = "NOMBRE";


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        et_name = findViewById(R.id.et_name);
        et_surname = findViewById(R.id.et_surname);
        et_email = findViewById(R.id.et_email);
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        if (outState != null) {
            outState.putString(KEY_NAME,et_name.getText().toString());
            outState.putString(KEY_SURNAME,et_surname.getText().toString());
            outState.putString(KEY_EMAIL,et_email.getText().toString());
        }
        super.onSaveInstanceState(outState);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        if (savedInstanceState != null ){
            if (savedInstanceState.containsKey(KEY_NAME) || savedInstanceState.containsKey(KEY_SURNAME) || savedInstanceState.containsKey(KEY_EMAIL)) {
                    et_name.setText(savedInstanceState.getString(KEY_NAME));
                    et_surname.setText(savedInstanceState.getString(KEY_SURNAME));
                    et_email.setText(savedInstanceState.getString(KEY_EMAIL));
            }
        }
    }
}