Tukukkk

I've got 2 activities that stores/get data from firebase, different data but they are related to each other.

The first activity stores for example different food dishes in a listview, and when I click on one of the items I get to the second activity where I can store different things under the first item i chose in my first activity. So for example, if I click on "PIZZA" I get to a new activity where I can store "Italian Pizza". And this is working fine. But I want to have a middle activity that will appear after my first activity, and in this middle activity I want to have a button that gets me to my second activity.

So between the first and second activity it is no problem, works like a charm. But when I try to use this middle activity with a button, it doesn't work. I guess it has to have something to do with the middle activity, that it is not "connected" with the database for the other activities. But I don't know, need help :)

I get this error when trying to click on the add button:

java.lang.NullPointerException: Can't pass null for argument 'pathString' in child()

    at com.google.firebase.database.DatabaseReference.child(Unknown Source:40)

First Activity:

public class Jobbliste extends AppCompatActivity {



    DatabaseReference databaseJobber;



    public static final String jobbnavn = "jobbnavn";

    public static final String jobbId = "jobbid";





    TextView jobbliste

    ListView listjobber;

    ImageView leggtiljobb;



    List<Jobber> listjobb;



    {



    }



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_jobbliste);



        databaseJobber = FirebaseDatabase.getInstance().getReference("Jobber");

        databaseVerktøy = FirebaseDatabase.getInstance().getReference("Verktøy");

        databaseAnsatt = FirebaseDatabase.getInstance().getReference("Ansatte");





        jobbliste = (TextView) findViewById(R.id.tvjobbliste);

        listjobber = (ListView) findViewById(R.id.lvjobbliste);



        listjobber.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {

            @Override

            public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {





                Jobber jobber = listjobb.get(i);



                Intent intent = new Intent(getApplicationContext(), MainActivity.class);



                intent.putExtra(jobbId, jobber.getJobbId());

                intent.putExtra(jobbnavn, jobber.getJobbnavn());



                startActivity(intent);



                return false;





            }

        });





        leggtiljobb = (ImageView) findViewById(R.id.tvleggtiljobb);



        listjobb = new ArrayList<>();

        søkjobb = new ArrayList<>();



        leggtiljobb.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                Intent leggtil = new Intent(Jobbliste.this, Leggtiljobb.class);

                startActivity(leggtil);



            }

        });





    }



    @Override

    protected void onStart() {

        super.onStart();



        databaseJobber.orderByChild("jobbnavn").addValueEventListener(new ValueEventListener() {

            @Override

            public void onDataChange(DataSnapshot dataSnapshot) {



                listjobb.clear();



                for (DataSnapshot jobberSnapshot : dataSnapshot.getChildren()) {



                    final Jobber jobber = jobberSnapshot.getValue(Jobber.class);



                    listjobb.add(jobber);



                    final listJobber adapter = new listJobber(Jobbliste.this, listjobb);

                    listjobber.setAdapter(adapter);



                    adapter.notifyDataSetChanged();



                }



            }



            @Override

            public void onCancelled(DatabaseError databaseError) {



            }

        });

    }

}

Second Activity:

public class Notater extends AppCompatActivity {



    public static final String jobbnavn = "jobbnavn";

    public static final String jobbId = "jobbid";





    TextView tvjobbnavn;

    EditText etnotater;

    Button btnlagrenotat;

    ListView lvnotater;

    Button btntest;

    TextView tvjobbnavn1;



    DatabaseReference databaseNotater;

    DatabaseReference databaseJobber;



    List<Notat> notater;

    List<Jobber> listjobb;



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_notater);





        tvjobbnavn = (TextView) findViewById(R.id.tvjobbnavn);

        tvjobbnavn1 = (TextView) findViewById(R.id.tvjobbnavn1);



        etnotater = (EditText) findViewById(R.id.etnotater);

        btnlagrenotat = (Button) findViewById(R.id.btnlagrenotat);

        lvnotater = (ListView) findViewById(R.id.lvnotater);

        btntest = (Button) findViewById(R.id.btntest);

        lvnotater.setItemsCanFocus(true);





        Intent intent = getIntent();



        notater = new ArrayList<>();

        listjobb = new ArrayList<>();





        String id = intent.getStringExtra(Jobbliste.jobbId);

        String navn = intent.getStringExtra(Jobbliste.jobbnavn);



        tvjobbnavn.setText(navn);





        databaseNotater = FirebaseDatabase.getInstance().getReference("Notater").child(id);

        databaseJobber = FirebaseDatabase.getInstance().getReference("Jobber").child(id);





        btnlagrenotat.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View view) {

                lagrenotat();



            }

        });



    }



    @Override

    protected void onStart() {

        super.onStart();



        databaseNotater.addValueEventListener(new ValueEventListener() {

            @Override

            public void onDataChange(DataSnapshot dataSnapshot) {

                notater.clear();



                for (DataSnapshot notatsnapshot : dataSnapshot.getChildren()) {

                    Notat notat = notatsnapshot.getValue(Notat.class);

                    notater.add(notat);





                }

                listNotater notatlistadapter = new listNotater(Notater.this, notater);



                lvnotater.setAdapter(notatlistadapter);



            }



            @Override

            public void onCancelled(DatabaseError databaseError) {



            }

        });

    }



    private void lagrenotat() {

        String notatavn = etnotater.getText().toString().trim();





        if (!TextUtils.isEmpty(notatavn)) {

            String id = databaseNotater.push().getKey();



            Notat notat = new Notat(id, notatavn);

            databaseNotater.child(id).setValue(notat);



        } else {

            Toast.makeText(this, "Skriv noe", Toast.LENGTH_SHORT).show();

        }



    }

}

My middle Activity:

public class MainActivity extends AppCompatActivity {



    public static final String jobbnavn = "jobbnavn";

    public static final String jobbId = "jobbid";



    Button add;

    TextView text;



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);



        add = (Button) findViewById(R.id.add);

        text = (TextView) findViewById(R.id.text);



        Intent intent = getIntent();





        String id = intent.getStringExtra(Jobbliste.jobbId);

        String navn = intent.getStringExtra(Jobbliste.jobbnavn);



        text.setText(navn);



        add.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                Intent leggtil = new Intent(MainActivity.this, Notater.class);

                startActivity(leggtil);





            }

        });

    }

}

Let's compare how you start Notater

From Jobbliste in your first, working version:

listjobber.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {

    @Override

    public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {

        Jobber jobber = listjobb.get(i);



        Intent intent = new Intent(getApplicationContext(), MainActivity.class);

        intent.putExtra(jobbId, jobber.getJobbId());

        intent.putExtra(jobbnavn, jobber.getJobbnavn());

        startActivity(intent);



        return false;

    }

});

From MainActivity:

add.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View v) {

            Intent leggtil = new Intent(MainActivity.this, Notater.class);

            startActivity(leggtil);

        }

    });

In Notater, you try to get the values for id and navn, but right now the Intent which was used to start Notater does not have any extras so both variables are null. This causes the NullPointerException.

There are two lines missing right before startActivity():

leggtil.putExtra(Jobbliste.jobbId, id);

leggtil.putExtra(Jobbliste.jobbnavn, navn);

(Please note that in order to be able to access the String variables id and navn from onClick(), you have to make them final.)