android 搜索 View 上的 java.lang.NullPointerException getCount

Question

我正在尝试在我的应用程序中实现搜索功能，它部分工作，当它找不到项目时应用程序崩溃并给我以下错误:

12-19 14:35:44.019  29694-29694/W/System.err﹕ at br.com.adapter.DespesaViewAdapter.getCount(DespesaViewAdapter.java:75)

12-19 14:35:44.020  29694-29694/W/System.err﹕ at br.com.representemais.DespesaActivity$1.onQueryTextChange(DespesaActivity.java:241)

上面几行是:

75: 返回 despesa.size();241:lv.setAdapter(广告)；

这是我的全部代码:

public class DespesaViewAdapter extends BaseAdapter {


    private Repositorio mRepositorio;
    private SearchView.OnQueryTextListener query;
    private Runnable frag;
    private DespesaActivity desp;


    private static LayoutInflater inflater=null;


    private List<DespesasDaViagemModel> despesa = new ArrayList<DespesasDaViagemModel>();


    public DespesaViewAdapter(Context context, Runnable fragmentDespesa, List<DespesasDaViagemModel> despesas) {
        this.inflater = LayoutInflater.from( context );
        this.despesa = despesas;
        mRepositorio = new Repositorio(context);
        frag = fragmentDespesa;



    }

    public DespesaViewAdapter(Context contextx, SearchView.OnQueryTextListener onQueryTextListener, List<DespesasDaViagemModel> despesa) {

        this.inflater = LayoutInflater.from( contextx );
        this.despesa = despesa;

        query = onQueryTextListener;



    }




    public int getCount() {
        return despesa.size();
    }

    public Object getItem(int position) {
        return position;
    }

    public long getItemId(int position) {
        return position;
    }

    public View getView(int position, View convertView, ViewGroup parent) {

        View vi=convertView;
        ViewHolder holder;
        if(convertView == null){
            vi = inflater.inflate(R.layout.despesa_activity, null);
            holder=new ViewHolder();
            holder.id = (TextView)vi.findViewById(R.id.despesaId);
            holder.data = (TextView)vi.findViewById(R.id.dataDespesa);
            holder.categoria = (TextView)vi.findViewById(R.id.despesaCategoria);
            holder.valor = (TextView)vi.findViewById(R.id.valorDespesa);

            View corCategoria = (View) vi.findViewById(R.id.corCategoria);
            corCategoria.setBackgroundResource(R.drawable.corner_categoria);
            GradientDrawable drawable = (GradientDrawable) corCategoria.getBackground();

            String corFormatada = (despesa.get(position).getCor());


            drawable.setColor(Color.parseColor(corFormatada));






            vi.setTag(holder);
        }else{
            holder = (ViewHolder)vi.getTag();
        }



        DespesasDaViagemModel item = new DespesasDaViagemModel();

        item = despesa.get(position);
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        Date date = null;
        try {
            date = df.parse(item.getData());
        } catch (ParseException e) {
            e.printStackTrace();
        }
        df.applyPattern("dd/MM/yyyy");
        String dataCriado = df.format(date);
        holder.id.setText(String.valueOf(item.getId()));
        holder.data.setText(dataCriado);
        holder.categoria.setText(item.getCategoria());
        holder.valor.setText("R$" + item.getValor());




        return vi;
    }

    public void setData(List<DespesasDaViagemModel> despesas){
        this.despesa.addAll(despesas);
        this.notifyDataSetChanged();
    }

    public class ViewHolder
    {
        TextView id;
        TextView data;
        TextView categoria;
        TextView valor;


    }
}


public class DespesaActivity extends ActionBarActivity {


    private String rm_IdViagem;
    private List<DespesasDaViagemModel> despesa = new ArrayList<DespesasDaViagemModel>();
    private boolean searchCheck;
    private SearchView searchView;
    private ProgressBar progressBar;
    private ListView lv;
    private LinearLayout footerLinearLayout;
    private DespesaViewAdapter ad;
    private DespesaViewAdapter ads;
    private ProgressDialog dialog;


    @Override
    public void onCreate(Bundle savedInstanceState) {


        super.onCreate(savedInstanceState);
        // TODO Auto-generated method stub
        setContentView(R.layout.despesa);

        getActionBar().setDisplayHomeAsUpEnabled(true);
        getActionBar().setHomeButtonEnabled(true);

        SecurePreferences mSessao = new SecurePreferences(DespesaActivity.this, "sessao");
        mSessao.put("menuAtual", "Despesas");

        lv = (ListView) findViewById(R.id.listaDespesa);


        Bundle parametros = getIntent().getExtras();
        if (parametros != null) {

            rm_IdViagem = parametros.getString("id_viagem");


        }

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // TODO Auto-generated method stub
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.menu, menu);


        MenuItem searchItem = menu.findItem(R.id.menu_search);


        searchView = (SearchView) MenuItemCompat.getActionView(searchItem);
        searchView.setQueryHint(this.getString(R.string.search));

        ((EditText) searchView.findViewById(android.support.v7.appcompat.R.id.search_src_text))
                .setHintTextColor(getResources().getColor(R.color.white));
        searchView.setOnQueryTextListener(OnQuerySearchView);


        if (rm_IdViagem != null) {

            new DownloadTask().execute();


        }

        menu.findItem(Menus.PROCURAR).setVisible(true);
        searchCheck = false;

        return super.onCreateOptionsMenu(menu);


    }

    public class DownloadTask extends AsyncTask<Void, Void, Void> {


        @Override
        protected void onPreExecute() {
            dialog = new ProgressDialog(DespesaActivity.this);
            // setup your dialog here
            dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
            dialog.setTitle("Carregando Despesas");
            dialog.setMessage("Aguarde...");
            dialog.setCancelable(false);
            dialog.show();

        }

        protected Void doInBackground(Void... params) {



            despesa = new ArrayList<DespesasDaViagemModel>();

            try {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {


                        Repositorio mRepositorio = new Repositorio(DespesaActivity.this);

                        List lista = mRepositorio.getDespesasViagensPorId("", Integer.valueOf(rm_IdViagem));

                        despesa = lista;


                        ad = new DespesaViewAdapter(DespesaActivity.this, this, despesa);

                        lv.setVerticalFadingEdgeEnabled(true);
                        lv.setVerticalScrollBarEnabled(true);

                        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

                            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                 //

                            }

                        });
                        lv.setAdapter(ad);

                        TextView emptyText = (TextView) findViewById(R.id.SemResultado);
                        lv.setEmptyView(emptyText);

                    }
                });


            } catch (Exception e) {
                e.printStackTrace();
            }


            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            if (dialog.isShowing()) {
                dialog.dismiss();
            }


        }
    }


    private SearchView.OnQueryTextListener OnQuerySearchView = new SearchView.OnQueryTextListener() {


        @Override
        public boolean onQueryTextSubmit(String arg0) {
            // TODO Auto-generated method stub
            return false;
        }

        @Override
        public boolean onQueryTextChange(String search) {

            // TODO Auto-generated method stub

            if (searchCheck) {
                // implement your search here




                despesa = new ArrayList<DespesasDaViagemModel>();
                try {


                    Repositorio mRepositorio = new Repositorio(DespesaActivity.this);


                    List listaDeDespesas = mRepositorio.getDespesasViagensPorId(search, Integer.valueOf(rm_IdViagem));

                    despesa = listaDeDespesas;


                    ad = new DespesaViewAdapter(DespesaActivity.this, this, despesa);


                    lv.setVerticalFadingEdgeEnabled(true);
                    lv.setVerticalScrollBarEnabled(true);

                    lv.setAdapter(ad);


                        TextView emptyText = (TextView) findViewById(R.id.SemResultado);
                        lv.setEmptyView(emptyText);


                } catch (Exception e) {
                    e.printStackTrace();
                }

            }
            return false;
        }


    };


    private static final int REFRESH = 1;
    private static final int SEARCH = 2;

    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public boolean onOptionsItemSelected(MenuItem item) {

        switch (item.getItemId()) {

            case Menus.PROCURAR:
                searchCheck = true;
                break;
            case android.R.id.home:
                super.onBackPressed();
                overridePendingTransition(R.anim.animation_back, R.anim.animation_back_leave);

            case REFRESH:

                return true;

            case SEARCH:

                return true;

            case R.id.menu_filtro:
                this.fnFiltrar();

                return true;

            case R.id.menu_atualizar:
                 /* dispara os repositorios a sincronizar */

                new Sincronizar(DespesaActivity.this, DespesaActivity.this).execute(0);


                return true;

        }


        return true;

    }


    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    @Override
    public void onBackPressed() {

        super.onBackPressed();
        overridePendingTransition(R.anim.animation_back, R.anim.animation_back_leave);
        finish();

    }

    private void fnFiltrar() {

        Intent intent = new Intent(this, FiltrarActivity.class);

        startActivity(intent);

    }


}

Answer 1

我猜你传递的是 null 而不是数组列表。只需尝试在适配器的 getCount() 方法中打印列表即可。

并在 doInBackground() 中

 List lista = mRepositorio.getDespesasViagensPorId("", Integer.valueOf(rm_IdViagem));
                    despesa.addAll(lista);

或

public int getCount() {
    if(despesa == null)
    {
       return 0;
    }
    return despesa.size();    
    }