I’m using retrofit api. Please check the screenshot below: I have category and sub category list in the dialog. On clicking “Ok” button, I have to fetch main category id, subcategory id , and sub category price. I used sparseBooleanArray. I’m able to fetch main_category id, but I get null pointer exception when try to fetch sub_category_id. Please help. 
Attached code below:
MainAdapter:
holder.select_category.setTag(position);
holder.select_category.setChecked(mSparseBooleanArray.get(position));
holder.select_category.setOnCheckedChangeListener(mCheckedChangeListener);
sublist = new ArrayList<>();
sublist=chat_list.get(position).getSubCategory();
subcategoryAdapter = new SubCategoryAdapter(context, sublist);
holder.recyclerView.setAdapter(subcategoryAdapter);
holder.recyclerView.setLayoutManager(new LinearLayoutManager(context));
holder.category.setText(chat_list.get(position).getMainCategoryName());
}
CompoundButton.OnCheckedChangeListener mCheckedChangeListener = new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
mSparseBooleanArray.put((Integer) buttonView.getTag(), isChecked);
}
};
public ArrayList<String> getCheckedItems() {
ArrayList<String> mTempArry = new ArrayList<String>();
for(int i=0;i<chat_list.size();i++) {
if(mSparseBooleanArray.get(i)) {
mTempArry.add(chat_list.get(i).getMainCategoryId());
//mTempArry.add(sublist.get(i).getSubCategoryId());
Log.e("MAINID",chat_list.get(i).getMainCategoryId());
}
}
return mTempArry;
}
SubAdapter:
public void onBindViewHolder(final DataObjectHolder holder, final int position) {
holder.subcategory.setText(sublist.get(position).getSubCategoryName());
Log.e("Sub Cat Name",sublist.get(position).getSubCategoryName());
holder.subcat.setTag(position);
holder.subcat.setChecked(mSparseBooleanArray.get(position));
holder.subcat.setOnCheckedChangeListener(mCheckedChangeListener);
cost_per_hr=holder.price.getText().toString();
}
CompoundButton.OnCheckedChangeListener mCheckedChangeListener = new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
mSparseBooleanArray.put((Integer) buttonView.getTag(), isChecked);
}
};
public ArrayList<String> getSubCheckedItems() {
ArrayList<String> mTempArry = new ArrayList<String>();
for(int i=0;i<sublist.size();i++) {
if(mSparseBooleanArray.get(i)) {
Log.e("TAG","INSIDE SUB");
mTempArry.add(sublist.get(i).getSubCategoryId());
mTempArry.add(cost_per_hr);
Log.e("SUBID",sublist.get(i).getSubCategoryId()+"::"+cost_per_hr);
}
}
return mTempArry;
}
@Override
public int getItemCount() {
return sublist.size();
}
Activity:
submit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
category.dismiss();
ArrayList<String> selectedItems = categoryAdapter.getCheckedItems();
try {
try {
for (int i = 0; i <= selectedItems.size(); i++) {
Log.e("Main", selectedItems.get(i));
}
} catch (Exception e) {
e.printStackTrace();
}
} catch (NumberFormatException e) {
e.printStackTrace();
}
ArrayList<String> selectedItems_one = subCategoryAdapter.getSubCheckedItems();
try {
for (int i = 0; i <= selectedItems_one.size(); i++) {
Log.e("Sub", selectedItems_one.size()+"");
}
} catch (NumberFormatException e) {
e.printStackTrace();
}
}
});
On clicking submit button, i get nullpointer exception for getSubcheckedItems() method.
Error:
java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.ArrayList com.app.qn.adapter.SubCategoryAdapter.getSubCheckedItems()' on a null object reference
at com.app.qn.activity.EditProfileActivity$3.onClick(EditProfileActivity.java:303)
at android.view.View.performClick(View.java:5675)
at android.view.View$PerformClick.run(View.java:22651)
at android.os.Handler.handleCallback(Handler.java:836)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:208)
at android.app.ActivityThread.main(ActivityThread.java:6267)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)
2019-04-17 17:48:13.793 19440-21355/com.app.qn E/NativeCrypto: ssl=0x774a444680 cert_verify_callback x509_store_ctx=0x772d7e8a28 arg=0x0
2019-04-17 17:48:13.793 19440-21355/com.app.qn E/NativeCrypto: ssl=0x774a444680 cert_verify_callback calling verifyCertificateChain authMethod=ECDHE_RSA
