How to pass information between screens, using Bundle and Classes with Get and Set?

Question

I’m trying to pass information from one screen to another.

I’ve tried to (2) two manners:

• 1) I created a class only to create variables and encapsulate the methods
• 2) Now, I’m trying to get past Berne without the encapsulated methods.

Problems 1): The problem is that whole the get stays null if I use on another screen unseen that of the Aboutscreen .

Problems 2): The problem is that is giving the following error, as it is below.

• ERROR:

06-16 15:28:26.235 16338-16338/com.vuforia.samples.Books E/Androidruntime: FATAL EXCEPTION: main Process: com.vuforia.samples.Books, PID: 16338 java.lang.Runtimeexception: Unable to instantiate Activity Componentinfo{com.vuforia.samples.Books/com.vuforia.samples.Books.app.Books.Books}: java.lang.Nullpointerexception: Attempt to invoke virtual method 'android.os.Bundle android.content.Intent.getExtras()' on a null Object Reference at android.app.Activitythread.performLaunchActivity(Activitythread.java:2495) at android.app.Activitythread.handleLaunchActivity(Activitythread.java:2650) at android.app.Activitythread. -wrap11(Activitythread.java) at android.app.Activitythread$H.handleMessage(Activitythread.java:1505) at android.os.Handler.dispatchMessage(Handler.java:111) at android.os.Looper.loop(Looper.java:207) at android.app.Activitythread.main(Activitythread.java:5776) at java.lang.reflect.Method.invoke(Native Method) at com.android.Internal.os.Zygoteinit$Methodandargscaller.run(Zygoteinit.java:888) at com.android.Internal.os.Zygoteinit.main(Zygoteinit.java:749) Caused by: java.lang.Nullpointerexception: Attempt to invoke virtual method 'android.os.Bundle android.content.Intent.getExtras()' on a null Object Reference at com.vuforia.samples.Books.app.Books.Books.(Books.java:138) at java.lang.Class.newInstance(Native Method) at android.app.Instrumentation.newActivity(Instrumentation.java:1072) at android.app.Activitythread.performLaunchActivity(Activitythread.java:2485) at android.app.Activitythread.handleLaunchActivity(Activitythread.java:2650)  at android.app.Activitythread. -wrap11(Activitythread.java)  at android.app.Activitythread$H.handleMessage(Activitythread.java:1505)  at android.os.Handler.dispatchMessage(Handler.java:111)  at android.os.Looper.loop(Looper.java:207)  at android.app.Activitythread.main(Activitythread.java:5776)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.Internal.os.Zygoteinit$Methodandargscaller.run(Zygoteinit.java:888)  at com.android.Internal.os.Zygoteinit.main(Zygoteinit.java:749)

- Aboutscreen.java:

/*===============================================================================
Copyright (c) 2016 PTC Inc. All Rights Reserved.

Copyright (c) 2012-2014 Qualcomm Connected Experiences, Inc. All Rights Reserved.

Vuforia is a trademark of PTC Inc., registered in the United States and other 
countries.
===============================================================================*/

package com.vuforia.samples.Books.ui.ActivityList;

import com.vuforia.samples.Books.R;
import com.vuforia.samples.Books.app.Books.Books;
import com.vuforia.samples.Books.app.Neoris.Shopping;
import android.Manifest;

import android.app.AlertDialog;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

import java.io.IOException;
import java.util.List;


public class AboutScreen extends FragmentActivity {

    private Button mStartButton;
    private String mClassToLaunch;
    private String mClassToLaunchPackage;

    private TextView txtShoppingName;
    private TextView txtShoppingCity;
    private TextView txtShoppingLat;
    private TextView txtShoppingLong;

    private Location location;
    private LocationManager locationManager;
    private Address endereco;

    private double latitude;
    private double longitude;
    private String nomeShopping;
    private String licenseKey;
    private String aKey;
    private String sKey;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.about_screen);


        Bundle extras = getIntent().getExtras();
        mClassToLaunchPackage = getPackageName();
        mClassToLaunch = mClassToLaunchPackage + "." + extras.getString("ACTIVITY_TO_LAUNCH");

        /**
         * VERIFICAÇÃO DA PERMISSÃO DO USUÁRIO AO USO DO GPS.
         */

        if(ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED) {

        } else {
            locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
            location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
        }

        if (location !=null){
            latitude = location.getLatitude();
            longitude = location.getLongitude();

            verificarShopping(latitude, longitude); //Verifica a Lat e Long, retorna o 'Nome do Shopping' e insere as Key's

            try {
                endereco = buscarEndereco(latitude, longitude);
            } catch (IOException e) {
                e.printStackTrace();
            }

        }


        mStartButton = (Button) findViewById(R.id.button_start);
        mStartButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {

                //Cria um Layout para o DialogFragment.
                AlertDialog.Builder mBuilder = new AlertDialog.Builder(AboutScreen.this);
                View mView = getLayoutInflater().inflate(R.layout.fragment_dialogo, null);

                Button mComecarButton = (Button) mView.findViewById(R.id.btn_comecar);

                txtShoppingName = (TextView) mView.findViewById(R.id.txtShoppingName);
                txtShoppingCity = (TextView) mView.findViewById(R.id.txtShoppingCity);
                txtShoppingLat = (TextView) mView.findViewById(R.id.txtShoppingLat);
                txtShoppingLong = (TextView) mView.findViewById(R.id.txtShoppingLong);

                //Insere as Informações ao DialogFragment.
                Shopping shop = new Shopping();

                txtShoppingName.setText(" " + nomeShopping);
                txtShoppingCity.setText(" " + endereco.getLocality());
                txtShoppingLat.setText(" " + latitude);
                txtShoppingLong.setText(" " + longitude);


                //Abre a Activity Books.
                mComecarButton.setOnClickListener(new OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Intent i = new Intent(AboutScreen.this, Books.class);
                        startActivity(i);
                    }
                });

                mBuilder.setView(mView);
                AlertDialog dialog = mBuilder.create();
                dialog.show();
            }
        });

    }

    //Busca em uma List os Endereços da Geolocalização do GPS.
    public Address buscarEndereco(double latitude, double longitude) throws IOException {
        Geocoder geocoder;
        Address address = null;
        List<Address> addresses;

        geocoder = new Geocoder(getApplicationContext());
        addresses = geocoder.getFromLocation(latitude, longitude, 1);

        if(addresses.size() > 0){
            address = addresses.get(0);
        }

        return address;
    }

    public String verificarShopping(double latitude, double longitude){

        Shopping shop = new Shopping();
        Bundle bundle = new Bundle();
        Intent intent = new Intent(AboutScreen.this, Books.class);


        if((this.latitude == latitude)&&(this.longitude == longitude)){
            /*FUNCIONA*/shop.setNome("Neoris");
            /*NÃO FUNCIONA EM OUTRA ACTIVITY, SOMENTE NESTA*/shop.setLicenseKey("Ad84Z0z/////AAAAGSgcOhPVvkoniWypHW2Dfsw+iX69sih5qx5JH1PEs92sM2xIhbsKnb2eTNkfBeQymsfgyRswpCDi2Ocu78RH+5+7/fXED7hJPLf3T7k4xKKLl4z8OKfCmr8jE0L5wQdJVV9L3tiHEoUx67M4b3ZSlO3/AzDLYi2/Zt3z8fuPo62osy469O+bKBsKKZtnyX9K7RYwJ2colMQ1bIhQERjg1w5cEZLHUacXAI1ndYhzS2Xl5iwAz98VZ65sptn+PrA5Xno55VGddt7rSBmvwuhZzeyShWnOqiYFhjWg80F3PFv2H/hYfIt4ML37yerJxS/n0z8yFv1H5gPi+Abd5nfaboz/xx1WgXf0yDvQKslFV+rr");

            nomeShopping = shop.getNome();
            licenseKey = shop.getLicenseKey();
            aKey = shop.getAccessKey();
            sKey = shop.getSecretKey();

            // CÓDIGO AQUI
            bundle.putString("aKey", "f854427b00cf89cb4909cf3780a22f1fe6dd1daa");
            bundle.putString("sKey", "16208b50224e2ff8d3c93f069d2c4adf739cea7a");
            intent.putExtras(bundle);

            startActivity(intent);


            return nomeShopping;
        }
        return "oi";
    }



}

• Books java.:

  package com.vuforia.samples.Books.app.Books;

  Intent intent = getIntent();
  Bundle bundle = intent.getExtras();
  String acKey = bundle.getString("aKey");
  String secKey = bundle.getString("sKey");
  
  Shopping shop = new Shopping();
  private String kAccessKey = acKey;
  private String kSecretKey = secKey;
  

Answer 1

What your mistake says:

EXCEPTION: main Process: com.vuforia.samples.Books, PID: 16338 java.lang.Runtimeexception: Unable to instantiate Activity

Your class Books is not registered as a Activity

This, because you are calling her as an Activity:

 Intent i = new Intent(AboutScreen.this, Books.class);
  startActivity(i);

To register as an Activity (if it is one) add the following line in the file Androidmanifest.xml within the TAG application:

 <activity android:name="com.vuforia.samples.Books"></activity>

Here is an example of how to pass parameters between Activity's

Class where we send the data:

public class ActivityUm extends AppCompatActivity {

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) {
        super.onCreate(savedInstanceState, persistentState);

        Button.class.cast(findViewById(R.id.all)).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Vamos chamar a ActivityDois!
                Intent i = new Intent(ActivityUm.this, ActivityDois.class);
//                // Informamos uma chave, para que na próxima tela ele consiga pegar o valor!
                i.putExtra("VALOR_1", "Este é o valor que vamso passar no parametro 1");
                i.putExtra("VALOR_2", 12345L);
                startActivity(i);
            }
        });
    }
}

Class where we will receive the data:

public class ActivityDois extends AppCompatActivity{


    @Override
    public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) {
        super.onCreate(savedInstanceState, persistentState);

        //Agora vamos pegar o valor, se o getIntent() não seja nulo!
        if(null != getIntent()){
            /** Pegamos o VALOR_1**/
            final String valor1 = getIntent().getStringExtra("VALOR_1");
            /** Caso seja nulo, o valor será -1**/
            final Long valor2 = getIntent().getLongExtra("VALOR_2", -1L);
        }
    }
}