Android - custom ArrayAdapter

Question

Could anybody help me solve my problem. I still trying work with DraggingListView and ArrayAdapter. Now i want realize delete element from listview by click, but when i making :

StableArrayAdapter.this.notifyDataSetChanged();

i get nullPointer Exception ...

here is my adapter:

public class StableArrayAdapter extends ArrayAdapter<Product> {
 final int INVALID_ID = -1;
 LayoutInflater lInflater;
 Context ctx;
 public static final String PREFS_NAME = "com.shvedchenko.skleroshop";
 public static final String PREFS_THEME = "theme";
 HashMap<Product, Integer> mIdMap = new HashMap<Product, Integer>();
 public StableArrayAdapter(Context context, int textViewResourceId, List<Product> prod) {
 super(context, textViewResourceId, /*objects*/prod);
 lInflater = (LayoutInflater) context
 .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
 ctx = context;
 for (int i = 0; i < prod.size(); ++i) {
 mIdMap.put(prod.get(i), i);
 }
 }
 // пункт списка
 @Override
 public View getView(final int position, View convertView, final ViewGroup parent) {
 // используем созданные, но не используемые view
 View view = convertView;
 if (view == null) {
 view = lInflater.inflate(R.layout.item, parent, false);
 }
 Product p = getItem(position);
 SharedPreferences pref = ctx.getSharedPreferences(PREFS_NAME, ctx.MODE_PRIVATE);
 int theme = pref.getInt(PREFS_THEME, 0); // getting Integer
 if(theme == 0)
 ((TextView) view.findViewById(R.id.tvDescr)).setTextColor(Color.WHITE);
 else
 ((TextView) view.findViewById(R.id.tvDescr)).setTextColor(Color.BLACK);
 ((TextView) view.findViewById(R.id.tvDescr)).setText(p.getProductName());
 ((ImageView) view.findViewById(R.id.ivImage)).setImageResource(p.getProductImage());
 ImageView iv = (ImageView)view.findViewById(R.id.ivImage);
 iv.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View view) {
 mIdMap.remove(getItem(position));
 System.out.println("FROM CLICK -- " + mIdMap.size() );
 /*for( Product p : mIdMap.keySet() ) {
 System.out.println( p.getProductName() );
 }*/
 //StableArrayAdapter.this.notifyDataSetChanged();
 }
 });
 return view;
 }
 /*@Override
 public Object getItem(int position) {
 return mIdMap.get(position);
 }*/
 @Override
 public long getItemId(int position) {
 if (position < 0 || position >= mIdMap.size()) {
 return INVALID_ID;
 }
 Product item = (Product) getItem(position);
 return mIdMap.get(item);
 }
 @Override
 public boolean hasStableIds() {
 return true;
 }
}

here is the error:

08-26 08:50:58.902 2167-2167/com.shvedchenko.skleroshop E/AndroidRuntime: FATAL EXCEPTION: main java.lang.NullPointerException at com.shvedchenko.skleroshop.StableArrayAdapter.getItemId(StableArrayAdapter.java:104) at android.widget.AdapterView.rememberSyncState(AdapterView.java:1195) at android.widget.AdapterView$AdapterDataSetObserver.onChanged(AdapterView.java:810) at android.widget.AbsListView$AdapterDataSetObserver.onChanged(AbsListView.java:5958) at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37) at android.widget.BaseAdapter.notifyDataSetChanged(BaseAdapter.java:50) at android.widget.ArrayAdapter.notifyDataSetChanged(ArrayAdapter.java:286) at com.shvedchenko.skleroshop.StableArrayAdapter1ドル.onClick(StableArrayAdapter.java:85) at android.view.View.performClick(View.java:4204) at android.view.View$PerformClick.run(View.java:17355) at android.os.Handler.handleCallback(Handler.java:725) at android.os.Handler.dispatchMessage(Handler.java:92) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:5041) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) at dalvik.system.NativeStart.main(Native Method)

/UPDATED/

My adapter now:

public class StableArrayAdapter extends ArrayAdapter<Product> {
 final int INVALID_ID = -1;
 LayoutInflater lInflater;
 Context ctx;
 public static final String PREFS_NAME = "com.shvedchenko.skleroshop";
 public static final String PREFS_THEME = "theme";
 HashMap<Product, Integer> mIdMap = new HashMap<Product, Integer>();
 ArrayList<Product> prods = new ArrayList<Product>();
 public StableArrayAdapter(Context context, int textViewResourceId, List<Product> prod) {
 super(context, textViewResourceId, /*objects*/prod);
 lInflater = (LayoutInflater) context
 .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
 ctx = context;
 for (int i = 0; i < prod.size(); ++i) {
 mIdMap.put(prod.get(i), i);
 prods.add(i,prod.get(i));
 }
 }
 // пункт списка
 @Override
 public View getView(final int position, View convertView, final ViewGroup parent) {
 // используем созданные, но не используемые view
 View view = convertView;
 if (view == null) {
 view = lInflater.inflate(R.layout.item, parent, false);
 }
 Product p = getItem(position);
 SharedPreferences pref = ctx.getSharedPreferences(PREFS_NAME, ctx.MODE_PRIVATE);
 int theme = pref.getInt(PREFS_THEME, 0); // getting Integer
 if(theme == 0)
 ((TextView) view.findViewById(R.id.tvDescr)).setTextColor(Color.WHITE);
 else
 ((TextView) view.findViewById(R.id.tvDescr)).setTextColor(Color.BLACK);
 ((TextView) view.findViewById(R.id.tvDescr)).setText(p.getProductName());
 ((ImageView) view.findViewById(R.id.ivImage)).setImageResource(p.getProductImage());
 ImageView iv = (ImageView)view.findViewById(R.id.ivImage);
 iv.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View view) {
 prods.remove(position);
 StableArrayAdapter.this.notifyData(prods);
 }
 });
 return view;
 }
 public void notifyData(List<Product> prod) {
 //First of all Clear Map
 mIdMap.clear();
 for (int i = 0; i < prod.size(); ++i) {
 mIdMap.put(prod.get(i), i);
 }
 notifyDataSetChanged();
 }
 @Override
 public long getItemId(int position) {
 if (position < 0 || position >= mIdMap.size()) {
 return INVALID_ID;
 }
 Product item = (Product) getItem(position);
 return mIdMap.get(item);
 }
 @Override
 public boolean hasStableIds() {
 return true;
 }
}

/ERROR/

08-26 09:53:19.270 2530-2530/com.shvedchenko.skleroshop E/AndroidRuntime: FATAL EXCEPTION: main java.lang.NullPointerException at com.shvedchenko.skleroshop.StableArrayAdapter.getItemId(StableArrayAdapter.java:122) at android.widget.AdapterView.rememberSyncState(AdapterView.java:1195) at android.widget.AdapterView$AdapterDataSetObserver.onChanged(AdapterView.java:810) at android.widget.AbsListView$AdapterDataSetObserver.onChanged(AbsListView.java:5958) at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37) at android.widget.BaseAdapter.notifyDataSetChanged(BaseAdapter.java:50) at android.widget.ArrayAdapter.notifyDataSetChanged(ArrayAdapter.java:286) at com.shvedchenko.skleroshop.StableArrayAdapter.notifyData(StableArrayAdapter.java:112) at com.shvedchenko.skleroshop.StableArrayAdapter1ドル.onClick(StableArrayAdapter.java:91)

What i am doing wrong?

TNX in advance!

• Kaushik: add this notifyDataSetChanged() inside constructer
• kbu: Unfortunately..still the same..
• kaka: It would help to know where the exception occurs.
• Kaushik: also post how u create object of StableArrayAdapter in activity

Answer 1

Correct code for adapter:

public class StableArrayAdapter extends ArrayAdapter<Product> {
 final int INVALID_ID = -1;
 LayoutInflater lInflater;
 Context ctx;
 public static final String PREFS_NAME = "com.shvedchenko.skleroshop";
 public static final String PREFS_THEME = "theme";
 HashMap<Product, Integer> mIdMap = new HashMap<Product, Integer>();
 public StableArrayAdapter(Context context, int textViewResourceId, List<Product> prod) {
 super(context, textViewResourceId, /*objects*/prod);
 lInflater = (LayoutInflater) context
 .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
 ctx = context;
 for (int i = 0; i < prod.size(); i++) {
 mIdMap.put(prod.get(i), i);
 }
 }
 // пункт списка
 @Override
 public View getView(final int position, View convertView, final ViewGroup parent) {
 // используем созданные, но не используемые view
 View view = convertView;
 if (view == null) {
 view = lInflater.inflate(R.layout.item, parent, false);
 }
 Product p = getItem(position);
 SharedPreferences pref = ctx.getSharedPreferences(PREFS_NAME, ctx.MODE_PRIVATE);
 int theme = pref.getInt(PREFS_THEME, 0); // getting Integer
 if(theme == 0)
 ((TextView) view.findViewById(R.id.tvDescr)).setTextColor(Color.WHITE);
 else
 ((TextView) view.findViewById(R.id.tvDescr)).setTextColor(Color.BLACK);
 ((TextView) view.findViewById(R.id.tvDescr)).setText(p.getProductName());
 ((ImageView) view.findViewById(R.id.ivImage)).setImageResource(p.getProductImage());
 ImageView iv = (ImageView)view.findViewById(R.id.ivImage);
 iv.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View view) {
 StableArrayAdapter.this.remove(getItem(position));
 StableArrayAdapter.this.notifyDataSetChanged();
 }
 });
 return view;
 }
 @Override
 public long getItemId(int position) {
 if (position < 0 || position >= mIdMap.size()) {
 return INVALID_ID;
 }
 Product item = (Product) getItem(position);
 return mIdMap.get(item);
 }
 @Override
 public boolean hasStableIds() {
 return true;
 }
}

Answer 2

Remove item from list

 list.remove(position);

Then call below method using adapter object.

 stableAdapter.notifyData(list);

Write a method in your Adapter class.

 public void notifyData(List<Product> prod)
 {
 //First of all Clear Map
 mIdMap.clear();
 for (int i = 0; i < prod.size(); ++i) {
 mIdMap.put(prod.get(i), i);
 } 
 notifyDataSetChanged();
 }

Call this method using adpater object