i am using recyclerview to display database. to use search I am using search view and Filterable interface. when in the search bar I start to enter the name, then the activity closes and throws it to the main screen.
Log
W/Filter: An exception occured during performFiltering()!
java.lang.NullPointerException: Attempt to invoke interface method 'java.util.Iterator java.util.List.iterator()' on a null object reference
at com.example.fixit.menu_java.service.CustomAdapter$1.performFiltering(CustomAdapter.java:82)
at android.widget.Filter$RequestHandler.handleMessage(Filter.java:236)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:224)
at android.os.HandlerThread.run(HandlerThread.java:67)
D/Surface: lockCanvas
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.grovers_repair, PID: 25967
java.lang.NullPointerException: Attempt to invoke interface method 'void java.util.List.clear()' on a null object reference
at com.example.fixit.menu_java.service.CustomAdapter$1.publishResults(CustomAdapter.java:97)
at android.widget.Filter$ResultsHandler.handleMessage(Filter.java:284)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:224)
at android.app.ActivityThread.main(ActivityThread.java:7551)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:995)
Adapter
ArrayList<ServiceData> objDBData;
private List<ServiceData> exampleList;
private List<ServiceData> exampleListFull;
public CustomAdapter(ArrayList<ServiceData> objDBData) {
this.objDBData = objDBData;
}
@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View singleRow = LayoutInflater.from(parent.getContext()).inflate(R.layout.service_list,parent,false);
return new MyViewHolder(singleRow);
}
@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
ServiceData objData = objDBData.get(position);
holder.city_name.setText(objData.getCity_name());
holder.company_name.setText(objData.getCompany_name());
holder.map_name.setText(objData.getMap_name());
holder.number.setText(objData.getNumber() "");
}
@Override
public int getItemCount() {
return objDBData == null ? 0 : objDBData.size();
}
public static class MyViewHolder extends RecyclerView.ViewHolder{
TextView city_name;
TextView company_name;
TextView map_name;
TextView number;
public MyViewHolder(@NonNull View itemView) {
super(itemView);
city_name = itemView.findViewById(R.id.city_card);
company_name = itemView.findViewById(R.id.company_card);
map_name = itemView.findViewById(R.id.map_card);
number = itemView.findViewById(R.id.number_card);
}
}
@Override
public Filter getFilter() {
return exampleFilter;
}
private Filter exampleFilter = new Filter() {
@Override
protected FilterResults performFiltering(CharSequence constraint) {
List<ServiceData> filteredList = new ArrayList<>();
if (constraint == null || constraint.length() == 0) {
filteredList.addAll(exampleListFull);
} else {
String filterPattern = constraint.toString().toLowerCase().trim();
for (ServiceData item : exampleListFull) {
if (item.getCity_name().toLowerCase().contains(filterPattern)) {
filteredList.add(item);
}
}
}
FilterResults results = new FilterResults();
results.values = filteredList;
return results;
}
@Override
protected void publishResults(CharSequence constraint, FilterResults results) {
exampleList.clear();
exampleList.addAll((List) results.values);
notifyDataSetChanged();
}
};
}
NewListService
public class NewListService extends AppCompatActivity {
MyDatabaseHelper myDB;
ArrayList<ServiceData> list;
CustomAdapter customAdapter;
RecyclerView recyclerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new_list_service);
recyclerView = findViewById(R.id.service_recycler);
myDB = new MyDatabaseHelper(this);
list = new ArrayList<>();
showData(recyclerView);
}
public void showData(View view){
try {
list = myDB.getAllData();
customAdapter = new CustomAdapter(list);
recyclerView.hasFixedSize();
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(customAdapter);
} catch (Exception e) {
Toast.makeText(this, "show data" e.getMessage(), Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.example_menu, menu);
MenuItem searchItem = menu.findItem(R.id.action_search);
SearchView searchView = (SearchView) searchItem.getActionView();
searchView.setImeOptions(EditorInfo.IME_ACTION_SEARCH);
searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
@Override
public boolean onQueryTextSubmit(String query) {
return false;
}
@Override
public boolean onQueryTextChange(String newText) {
customAdapter.getFilter().filter(newText);
return false;
}
});
return true;
}
}
MyDatabaseHelper
public class MyDatabaseHelper extends SQLiteAssetHelper {
private static final String DATABASE_NAME = "services.db";
private static final int DATABASE_VERSION = 1;
Context context;
public MyDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
this.context = context;
setForcedUpgrade(1);
}
public ArrayList<ServiceData> getAllData(){
try {
ArrayList<ServiceData> list = new ArrayList<>();
SQLiteDatabase sqLiteDatabase = getWritableDatabase();
if(sqLiteDatabase != null){
Cursor cursor = sqLiteDatabase.rawQuery("select * from locate",null);
if(cursor.getCount() != 0){
while (cursor.moveToNext()){
String city_name = cursor.getString(1);
String company_name = cursor.getString(2);
String map_name = cursor.getString(3);
String number = cursor.getString(4);
String web = cursor.getString(5);
String geo = cursor.getString(6);
list.add(new ServiceData(city_name,company_name,
map_name,number,web,geo));
}
return list;
}
else {
Toast.makeText(context, "No data retired", Toast.LENGTH_SHORT).show();
return null;
}
}
else {
Toast.makeText(context, "Data is null", Toast.LENGTH_SHORT).show();
return null;
}
} catch (Exception e) {
Toast.makeText(context, "getalldata" e.getMessage(), Toast.LENGTH_SHORT).show();
e.printStackTrace();
return null;
}
}
public int getUpgradeVersion() {
SQLiteDatabase db = getReadableDatabase();
SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
String [] sqlSelect = {"MAX (version)"};
String sqlTables = "upgrades";
qb.setTables(sqlTables);
Cursor c = qb.query(db, sqlSelect, null, null,
null, null, null);
int v = 0;
c.moveToFirst();
if (!c.isAfterLast()) {
v = c.getInt(0);
}
c.close();
return v;
}
}
please help me figure out what the problem is
CodePudding user response：
You have not instantiated the Lists exampleList and exampleListFull. Default values are null.
Calling clear() on a null object instead of a List throws the infamous NullPointerException.
And for the iterator error, you are calling addAll(exampleListFull) which means that it tries to iterate over a null object.