NullPointer Exception While Doing Search Feature for ListView With BaseAdapter

Question

I just finished adding a search feature to my android widget to search through a list of the users installed applications. My app installs fine and everything but when I go to s

Answer 1

Seems that mListAppInfo is null in

@Override
public int getCount() {
    return mListAppInfo.size();
}

Which makes me suppose that for some reason your call to getInstalledApplications when you instantiate the adapter returns null.

Answer 2

Your list contains appInfo.packageName not appInfo.name.

In performFiltering method you are adding appInfo.name to filtered list. Instead you should add appInfo.packageName.

Your for loop should be like this

 for (ApplicationInfo appInfo : originalListAppInfo) {
        String somefield = appInfo.packageName;
        if (somefield.toLowerCase().contains(constraint.toString())) {
              myFilteredAppList.add(appInfo);
        }
  }

This should work. And never forget to check for null values in publishResults method

 @Override
protected void publishResults(CharSequence constraint, FilterResults results) {

  if(results.values != null)
  {
    mListAppInfo = (List<ApplicationInfo>)results.values;
    notifyDataSetChanged();
  }

}

Answer 3

Add this code before for loop:

if (constraint.length() == 0) {
myFilteredAppList.addAll(originalListAppInfo);
} 

i.e

@Override
    public Filter getFilter() {
        if(filter == null) {
            filter = new Filter() {
                @Override
                protected FilterResults performFiltering(CharSequence constraint) {
                    FilterResults results = new FilterResults();
                    List<ApplicationInfo> myFilteredAppList = new ArrayList<ApplicationInfo>();
                    constraint = constraint.toString().toLowerCase();

                     if (constraint.length() == 0) {
                         myFilteredAppList.addAll(originalListAppInfo);
                        } 

                    for (ApplicationInfo appInfo : originalListAppInfo) {
                        String somefield = appInfo.name;
                        if (somefield.toLowerCase().contains(constraint.toString())) {
                            myFilteredAppList.add(appInfo);
                        }
                    }
                    results.count = myFilteredAppList.size();
                    results.values = myFilteredAppList;
                    return results;
                }

                @Override
                protected void publishResults(CharSequence constraint, FilterResults results) {
                    mListAppInfo = (List<ApplicationInfo>)results.values;
                    notifyDataSetChanged();
                }
            };
        }
        return filter;
    }