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NPE while filter list with io.reactivex.Observable

I facing with problem while try to filter ArrayList of String as Observable.

ArrayList

String

Observable

All works fine if:

MatrixCursor suggestionsCursor =
new MatrixCursor(new StringBaseColumns._ID, COLUMN_FIELD_NO);

for (int i = 0; i < data.size(); i++)
if (data.get(i) != null)
if (data.get(i).toLowerCase().contains(newText.toLowerCase()))
filtered.add(data.get(i));


int key = 0;
for (String suggestion : filtered)
suggestionsCursor.addRow(new Objectkey++, suggestion);



But not if

MatrixCursor suggestionsCursor =
new MatrixCursor(new StringBaseColumns._ID, COLUMN_FIELD_NO);

Observable.fromIterable(data)
.filter(it->it!=null && it.toLowerCase().contains(newText.toLowerCase()))
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.toList()
.subscribe(strings ->
int key = 0;
for (String suggestion : strings)
suggestionsCursor.addRow(new Objectkey++, suggestion);

);


Because I get an error

io.reactivex.exceptions.OnErrorNotImplementedException: The iterator
returned a null value

Where am I wrong here?

3 Answers
3

As mentioned in the comment, null values in the iterable sequence are not supported. This check is enforced in the ObservableFromIterable.java class:

null

ObservableFromIterable.java

v = ObjectHelper.requireNonNull(it.next(), "The iterator returned a null value");


This also means that a filter like this does not help

.filter(it -> it != null)


In any case, a good rule of thumb will be to handle error exceptions

Observable.fromIterable(data)
.filter(it->it!=null && it.toLowerCase().contains(newText.toLowerCase()))
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.toList()
.subscribe(strings ->
int key = 0;
for (String suggestion : strings)
suggestionsCursor.addRow(new Objectkey++, suggestion);

, error ->
/* handle exceptions here */
);


You could use the Iterable Extensions library (IxJava) for preprocessing, which let's you work with nulls:

null

Observable.fromIterable(
Ix.from(data)
.filter(it -> it != null
&& it.toLowerCase().contains(newText.toLowerCase())
)
)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.toList()
.subscribe(strings ->
int key = 0;
for (String suggestion : strings)
suggestionsCursor.addRow(new Objectkey++, suggestion);

,
Throwable::printStackTrace);


Both answears are good, but I found easier solution.

data.removeAll(Collections.singleton(null));


After populate data with Strings

Strings

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