Error opening Activity: The <application> stopped

Question

I have a file VigasFragment.java with a button that when touched should open the Activity VigMetBiapsb.java, however some error occurs, closing the application.

Vigasfragment.java:

public class VigasFragment extends Fragment {

Button btnBiapsb;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.vigas_fragment, container, false);

    // ////////////////////////////////////////////////////////////////////////////////
    btnBiapsb = (Button) rootView.findViewById(R.id.biapsb);
    btnBiapsb.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            Intent intBiapsb = new Intent(v.getContext(), VigMetBiapsb.class);
            startActivityForResult(intBiapsb, 0);
        }
    });
    // ////////////////////////////////////////////////////////////////////////////////

        return rootView;

    }// fecha onCreateView

}

Vigmetbiapsb.java:

    public class VigMetBiapsb extends Activity {

        int porctAlt, porctLarg;

        EditText edtVao = (EditText) findViewById(R.id.vao);
        final double edtVaoNum = Double.parseDouble(edtVao.getText().toString());

        Button calcBiapsb = (Button) fi

ndViewById(R.id.calc_biapsb);

    TextView secaoBiapsb;

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

        // Spinner
        Spinner spnCargas = (Spinner) findViewById(R.id.spn_cargas);
        ArrayAdapter<CharSequence> spnAdapter = ArrayAdapter.createFromResource(this, R.array.str_cargas, R.layout.spinner_style);
        spnAdapter.setDropDownViewResource(R.layout.spinner_dropdown_style);
        spnCargas.setAdapter(spnAdapter);
        // Spinner

        spnCargas.setOnItemSelectedListener(
                new AdapterView.OnItemSelectedListener() {

                    public void onItemSelected(AdapterView<?> spnAdpView, View v, int carga, long id) {

                        if(spnAdpView.getItemAtPosition(carga).toString() == "Cargas pequenas"){ porctAlt = 4; porctLarg = 40; }
                        else if(spnAdpView.getItemAtPosition(carga).toString() == "Cargas médias"){ porctAlt = 5; porctLarg = 50; }
                        else { porctAlt = 6; porctLarg = 60; }

                    }// fecha onItemSelected

                    public void onNothingSelected(AdapterView<?> arg0){}
                }//fecha OnItemSelectedListener
        ); // fecha setOnItemSelectedListener

        calcBiapsb.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                if(edtVaoNum != 0){
                    double alt = edtVaoNum * porctAlt;
                    double larg = alt / 100 * porctLarg;

                    secaoBiapsb = (TextView) findViewById(R.id.valorsec);
                    secaoBiapsb.setText(String.valueOf(alt)+" x "+String.valueOf(larg));
                }
                else {
                    Toast.makeText(getApplicationContext(), "Informe o tamanho do vão", Toast.LENGTH_SHORT).show();
                 }
            }
        });

    } //fecha onCreate
}

I believe the error is in the code of VigMetBiapsb.java because when I leave only the method onCreate() within the class VigMetBiapsb, to Activity opens normally.

Errors of the Logcat at the touch of the button btnBiapsb

Errors of the Logcat at the touch of the button btnBiapsb

Answer 1

The problem is that this initiating their View's in their declaration within the Activity. What makes the method findViewById be called on the builder of your Activity. And at that moment yours View has not yet been built, generating the NullPointerException.

Migrate this entire startup to onCreate, after the setContentView, as well as the other initializations you do.

Change of:

public class VigMetBiapsb extends Activity {

    EditText edtVao = (EditText) findViewById(R.id.vao);
    final double edtVaoNum = Double.parseDouble(edtVao.getText().toString());
    Button calcBiapsb = (Button) findViewById(R.id.calc_biapsb);

    // ...
}

To:

public class VigMetBiapsb extends Activity {

    int porctAlt, porctLarg;
    double edtVaoNum;

    EditText edtVao;
    Button calcBiapsb;
    TextView secaoBiapsb;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // Sua inicializacao atual...

        edtVao = (EditText) findViewById(R.id.vao);

        // Isso nao vai dar erro? edtVao esta preenchido nesse momento?
        edtVaoNum = Double.parseDouble(edtVao.getText().toString());

        calcBiapsb = (Button) findViewById(R.id.calc_biapsb);
    }
}

Answer 2

I don’t think you need to give this startActivityForResult(intBiapsb, 0); Yes only one starActivity(intBiapsb);