MainActivity retrieves the ID of the item from my list and I would like to send it to a class to create actions but

Question

I'm new to java and android

MainActivity retrieves the ID of the item from my list and I would like to send it to a class to create actions but this error appears:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.File android.content.Context.getDatabasePath(java.lang.String)' on a null object reference

thank you

ShowContact :

public class ShowContactActivity extends AppCompatActivity {
    private ContactDbAdapter db;

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

        Intent intent = getIntent();
        final Long id = intent.getExtras().getLong("Id");


        final ActionsContacts actions = new ActionsContacts(id);

        FloatingActionButton floatTelephone = findViewById(R.id.floatTelephone);
        floatTelephone.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                actions.call();
            }
        });


        fillData(id);
    }

ActionsContact :

`public class ActionsContacts extends AppCompatActivity{

private ContactDbAdapter db;

private String SelectedTel,
        SelectedEmail,
        SelectedAdresse,
        SelectedComplement,
        SelectedCodePostale,
        SelectedVille;

ActionsContacts(long id){


    db = new ContactDbAdapter(this);
    db.open();

    /**
     * Récupération des données en bdd car non affichées dans la ligne du listView
     */
    //Intent intent = getIntent();
    //final Long id = intent.getExtras().getLong("Id");

    Cursor c = db.fetchContact(id);
    startManagingCursor(c);



    this.SelectedTel = c.getString(c.getColumnIndex("new_telephone"));
    this.SelectedEmail = c.getString(c.getColumnIndex("new_email"));

    this.SelectedAdresse = c.getString(c.getColumnIndex("new_adresse"));
    this.SelectedComplement = c.getString(c.getColumnIndex("new_complement"));
    this.SelectedCodePostale = c.getString(c.getColumnIndex("new_codepostale"));
    this.SelectedVille = c.getString(c.getColumnIndex("new_ville"));
}

public void call(){
    Uri number = Uri.parse("tel:" + SelectedTel);
    Intent callIntent = new Intent(Intent.ACTION_DIAL, number);
    startActivity(callIntent);
}`

MainActivity :

   final ListView list_view_contacts = (ListView) findViewById(R.id.list_view_contacts);

    db = new ContactDbAdapter(this);
    db.open();

    fillData();

    registerForContextMenu(list_view_contacts);


    list_view_contacts.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            /**
             * permet de faire passer l'ID de cette activité (MainActivity) vers l'activité ShowContactActivity
             */
            Intent i = new Intent(MainActivity.this, ShowContactActivity.class);
            i.putExtra("Id", id);
            startActivity(i);

        }
    });

}



/**
 * Redirection vers l'activité : CreateContact
 */
public void openActivityCreateContact(){
    Intent intent = new Intent(this, CreateContactActivity.class);
    startActivity(intent);
}



@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
    super.onCreateContextMenu(menu, v, menuInfo);

    /** appeller sms email localiser supprimer */
    /**
     * Menu contextuel qui seront affichés lors d'un appui long
     */
    menu.add(0, v.getId(), 0, "Appeler");
    menu.add(0, v.getId(), 0, "Envoyer un SMS");
    menu.add(0, v.getId(), 0, "Envoyer un Email");
    menu.add(0, v.getId(), 0, "Voir l'adresse du contact");
    menu.add(0, v.getId(), 0, "Supprimer le contact");
}

@Override
public boolean onContextItemSelected(MenuItem item) {

    /**
     * Récupération de l'ID en fonction de la position de la ligne dans la listView
     */
    final ListView list_view_contacts = (ListView) findViewById(R.id.list_view_contacts);

    AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
    Cursor SelectedCursor = (Cursor) list_view_contacts.getItemAtPosition(info.position);

    final long id = SelectedCursor.getLong(SelectedCursor.getColumnIndex("_id"));


    /**
     * Actions menu contextuel
     */

    ActionsContacts actions = new ActionsContacts(id);

    if (item.getTitle() == "Supprimer le contact"){
        alertDelete(id);
        fillData();
    }

    if (item.getTitle() == "Appeler"){
        actions.call();
    }

    if (item.getTitle() == "Envoyer un SMS"){
        actions.message();
    }

    if (item.getTitle() == "Envoyer un Email"){
        actions.email();
    }

    if (item.getTitle() == "Voir l'adresse du contact"){
        actions.map();
    }
    return true;
}

Answer 1

If you get the crash error after clicking at item list, try to get the id at your ShowContact for something like below:

final Long id = getIntent().getExtras().getLong("Id");

or maybe:

Bundle bun = getIntent();
final Long id = bun.getExtras().getLong("Id");