The easiest way to transform collection to array?
Where x is the collection:
Foo[] foos = x.toArray(new Foo[x.size()]);
Alternative solution to the updated question using Java 8:
Bar[] result = foos.stream() .map(x -> new Bar(x)) .toArray(size -> new Bar[size]);
If you use it more than once or in a loop, you could define a constant
public static final Foo[] FOO = new Foo[]{};and do the conversion it like
Foo[] foos = fooCollection.toArray(FOO);The toArray method will take the empty array to determine the correct type of the target array and create a new array for you.
Here's my proposal for the update:
Collection<Foo> foos = new ArrayList<Foo>();Collection<Bar> temp = new ArrayList<Bar>();for (Foo foo:foos) temp.add(new Bar(foo));Bar[] bars = temp.toArray(new Bar[]{});