How to remove all null elements from a ArrayList or String Array?

Question

I try with a loop like that

// ArrayList tourists

for (Tourist t : tourists) {
    if (t != null) {     
        t.setId(idForm); 
    }   
}

Answer 1

I used the stream interface together with the stream operation collect and a helper-method to generate an new list.

tourists.stream().filter(this::isNotNull).collect(Collectors.toList());

private <T> boolean isNotNull(final T item) {
    return  item != null;
}

Answer 2

Using Java 8, you can do this using stream() and filter()

tourists = tourists.stream().filter(t -> t != null).collect(Collectors.toList())

or

tourists = tourists.stream().filter(Objects::nonNull).collect(Collectors.toList())

For more info : Java 8 - Streams

Answer 3

List<String> colors = new ArrayList<>(
Arrays.asList("RED", null, "BLUE", null, "GREEN"));
// using removeIf() + Objects.isNull()
colors.removeIf(Objects::isNull);

Answer 4

This is easy way to remove default null values from arraylist

     tourists.removeAll(Arrays.asList(null));  

otherwise String value "null" remove from arraylist

       tourists.removeAll(Arrays.asList("null"));  

Answer 5

The Objects class has a nonNull Predicate that can be used with filter.

For example:

tourists.stream().filter(Objects::nonNull).collect(Collectors.toList());

Answer 6

Similar to @Lithium answer but does not throw a "List may not contain type null" error:

   list.removeAll(Collections.<T>singleton(null));