我有一个带有列表视图的应用程序，可以打开根据不同字符串更改的活动。我可以将项目添加到个性化页面。一切正常，但如果我使用＆＃34; if＆＃34;它只通过MainActivity打开活动就可以了。如果我打开最喜欢的应用程序页面崩溃我并给我错误，如果＆＃34;方法！我只是不明白为什么！我希望你能帮助我！
致命的例外：主要
过程：com.chiari.nicola.provaricetta，PID：6720 主题：主题：{} java.lang.NullPointerException：尝试调用虚方法 ＆＃39; boolean java.lang.String.equals（java.lang.Object）＆＃39;在null对象上 参考 在com.chiari.nicola.provaricetta.Tab1.onCreateView（Tab1.java:68）
public class Tab1 extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View v =inflater.inflate(R.layout.tab_1,container,false);
Intent intent = getActivity().getIntent();
String Titolo_ricetta = intent.getStringExtra("Titolo_ricetta");
String Tempo_prep = intent.getStringExtra("Tempo_prep");
String Immagine_url = intent.getStringExtra("Immagine_url");
String Calore = intent.getStringExtra("Calore");
String Glutine = intent.getStringExtra("Glutine");
String Latticini = intent.getStringExtra("Latticini");
String Uova = intent.getStringExtra("Uova");
String Difficoltà = intent.getStringExtra("Difficoltà");
String Kalorie = intent.getStringExtra("Kalorie");
String Porzioni = intent.getStringExtra("Porzioni");
String Costo = intent.getStringExtra("Costo");
String Ingredienti = intent.getStringExtra("Ingredinti");
String Consigli = intent.getStringExtra("Consigli");
// make a TextView in activity_list_item_detail.xml called "name"
TextView nameTextView = (TextView) v.findViewById(R.id.titolo);
nameTextView .setText(Titolo_ricetta);
ImageView Immage_url= (ImageView) v.findViewById(R.id.Immagine_url);
Picasso.with(getActivity()).load(Immagine_url).fit().centerCrop().placeholder(R.drawable.piatto).error(R.drawable.x).into(Immage_url);
ImageView Im_calore= (ImageView) v.findViewById(R.id.Im_calore);
if (Calore.equals("c_no")) {
Im_calore.setImageDrawable(getResources().getDrawable(R.drawable.fire));
}else{}
ImageView Im_glutine= (ImageView) v.findViewById(R.id.Im_glutine);
if (Glutine.equals("g_no")) {
Im_glutine.setImageDrawable(getResources().getDrawable(R.drawable.spiga_barrata));
}else{}
ImageView Im_latticini= (ImageView) v.findViewById(R.id.Im_latticini);
if (Latticini.equals("l_no")) {
Im_latticini.setImageDrawable(getResources().getDrawable(R.drawable.mucca));
}else{}
ImageView Im_uova= (ImageView) v.findViewById(R.id.Im_uova);
if (Uova.equals("u_no")) {
Im_uova.setImageDrawable(getResources().getDrawable(R.drawable.gallina));
}else{}
ImageView Im_difficoltà= (ImageView) v.findViewById(R.id.Im_difficoltà);
if (Difficoltà.equals("bassa")) {Im_difficoltà.setImageDrawable(getResources().getDrawable(R.drawable.facile));}else if (Difficoltà.equals("media")) {Im_difficoltà.setImageDrawable(getResources().getDrawable(R.drawable.medio));}else if (Difficoltà.equals("alta")) {Im_difficoltà.setImageDrawable(getResources().getDrawable(R.drawable.difficile));}else{Im_difficoltà.setImageDrawable(getResources().getDrawable(R.drawable.x));}
TextView tempo=(TextView) v.findViewById(R.id.tempo_ricetta);
tempo.setText(Tempo_prep);
TextView kalorie=(TextView) v.findViewById(R.id.kalorie);
kalorie.setText(Kalorie);
TextView porzioni=(TextView) v.findViewById(R.id.porzioni);
porzioni.setText(Porzioni);
ImageView Im_costo= (ImageView) v.findViewById(R.id.Im_costo);
if (Costo.equals("basso")) {
Im_costo.setImageDrawable(
getResources().getDrawable(R.drawable.costo_basso));
}else if (Costo.equals("medio")) {
Im_costo.setImageDrawable(
getResources().getDrawable(R.drawable.costo_medio));
}else if (Costo.equals("alto")) {Im_costo.setImageDrawable(
getResources().getDrawable(R.drawable.costoso));}
else{Im_costo.setImageDrawable(
getResources().getDrawable(R.drawable.x));}
TextView ingredienti=(TextView) v.findViewById(R.id.ingredinti_txt);
ingredienti.setText(Ingredienti);
TextView consigli=(TextView) v.findViewById(R.id.consigli);
consigli.setText(Consigli);
String Scrittura_sezioni = getResources().getString(R.string.Scrittura_sezioni);
Typeface intro=Typeface.createFromAsset(getContext().getAssets(), Scrittura_sezioni);
TextView intro_text=(TextView)v.findViewById(R.id.intro);
intro_text.setTypeface(intro);
Typeface ingre=Typeface.createFromAsset(getContext().getAssets(), Scrittura_sezioni);
TextView ingre_text=(TextView)v.findViewById(R.id.ingredienti);
ingre_text.setTypeface(ingre);
preferiti.java
public class preferiti extends AppCompatActivity implements SearchView.OnQueryTextListener{
public static final String ARG_ITEM_ID = "favorite_list";
ListView favoriteList;
SharedPreference sharedPreference;
List<Ricette> countryList;
Activity activity;
CustomAdapter productListAdapter;
private Toolbar mToolbar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_preferiti);
activity = this;
//IMPOSTAZIONI TOOLBAR
mToolbar = (Toolbar) findViewById(R.id.tool_bar_preferiti);
setSupportActionBar(mToolbar);
mToolbar.setNavigationIcon(R.mipmap.ic_keyboard_arrow_left_white_24dp);
mToolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onBackPressed();
}
});
Typeface intro=Typeface.createFromAsset(getApplication().getAssets(), "Scrittura_titoli.ttf");
TextView intro_text=(TextView) findViewById(R.id.titolo_dolci);
intro_text.setTypeface(intro);
//FINE IMPOSTAZIONI TOOLBAR
// Get favorite items from SharedPreferences.
sharedPreference = new SharedPreference();
countryList = sharedPreference.getFavorites(activity);
if (countryList == null) {
showAlert(getResources().getString(R.string.no_favorites_items),
getResources().getString(R.string.no_favorites_msg));
} else {
if (countryList.size() == 0) {
showAlert(
getResources().getString(R.string.no_favorites_items),
getResources().getString(R.string.no_favorites_msg));
}
favoriteList = (ListView) findViewById(R.id.lista_preferiti);
if (countryList != null) {
productListAdapter = new CustomAdapter(activity, (ArrayList<Ricette>) countryList);
favoriteList.setAdapter(productListAdapter);
favoriteList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View arg1,
int position, long arg3) {
Ricette ricette = (Ricette) ((CustomAdapter) parent.getAdapter()).getItem(position);
Intent intent = new Intent(getApplication(), ListItemDetail.class);
intent.putExtra("Titolo_ricetta", ricette.getTitolo_ricetta());
intent.putExtra("Tempo_prep", ricette.getTempo_prep());
intent.putExtra("Immagine_url", ricette.getImmagine_url());
intent.putExtra("Calore",ricette.getCalore());
intent.putExtra("Glutine",ricette.getGlutine());
intent.putExtra("Latticini",ricette.getLatticini());
intent.putExtra("Uova",ricette.getUova());
intent.putExtra("Difficoltà",ricette.getDifficoltà());
intent.putExtra("Kalorie",ricette.getKalorie());
intent.putExtra("Porzioni",ricette.getPorzioni());
intent.putExtra("Costo",ricette.getCosto());
intent.putExtra("Ingredinti",ricette.getIngredinti());
intent.putExtra("Consigli",ricette.getConsigli());
intent.putExtra("Istruzione_1",ricette.getIstruzione_1());
intent.putExtra("Istruzione_2",ricette.getIstruzione_2());
intent.putExtra("Immagine_1",ricette.getImmagine_1());
intent.putExtra("Immagine_2",ricette.getImmagine_2());
intent.putExtra("Immagine_3",ricette.getImmagine_3());
intent.putExtra("Immagine_4",ricette.getImmagine_4());
intent.putExtra("Immagine_5",ricette.getImmagine_5());
intent.putExtra("Immagine_6",ricette.getImmagine_6());
intent.putExtra("Im_altr_1",ricette.getIm_altr_1());
intent.putExtra("Im_altr_2",ricette.getIm_altr_2());
intent.putExtra("Im_altr_3",ricette.getIm_altr_3());
intent.putExtra("Im_altr_4",ricette.getIm_altr_4());
intent.putExtra("Im_altr_5",ricette.getIm_altr_5());
intent.putExtra("Im_altr_6",ricette.getIm_altr_6());
startActivity(intent);
}
});
favoriteList
.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(
AdapterView<?> parent, View view,
int position, long id) {
ImageView button = (ImageView) view
.findViewById(R.id.imgbtn_favorite);
String tag = button.getTag().toString();
if (tag.equalsIgnoreCase("grey")) {
sharedPreference.addFavorite(activity,
countryList.get(position));
Toast.makeText(
activity,
activity.getResources().getString(
R.string.add_favr),
Toast.LENGTH_SHORT).show();
button.setTag("red");
button.setImageResource(R.drawable.heart_red);
} else {
sharedPreference.removeFavorite(activity,
countryList.get(position));
button.setTag("grey");
button.setImageResource(R.drawable.heart_grey);
productListAdapter.remove(countryList
.get(position));
Toast.makeText(
activity,
activity.getResources().getString(
R.string.remove_favr),
Toast.LENGTH_SHORT).show();
}
return true;
}
});
}
}
}
public void showAlert(String title, String message) {
if (activity != null && !activity.isFinishing()) {
AlertDialog alertDialog = new AlertDialog.Builder(activity)
.create();
alertDialog.setTitle(title);
alertDialog.setMessage(message);
alertDialog.setCancelable(false);
// setting OK Button
alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "OK",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
// activity.finish();
getFragmentManager().popBackStackImmediate();
}
});
alertDialog.show();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
SearchView searchView = (SearchView) MenuItemCompat.getActionView(menu.findItem(R.id.action_search));
searchView.setOnQueryTextListener(this);
return super.onCreateOptionsMenu(menu);
}
//IMPOSTAZIONI PER LA RICERCA
@Override
public boolean onQueryTextChange(String newText) {
productListAdapter.getFilter().filter(newText);
return false;}
@Override
public boolean onQueryTextSubmit(String query) {
return false;
}
//FINE IMPOSTAZIONI PER LA RICERCA
答案 0 :(得分：0)
e.g。
if(Calore != null){
if (Calore.equals("c_no"))