iterable

I have Book and BookList classes. BookList is something like this: public class BookList { private final List<Book> bList = new ArrayList<Book>(); public int size() { return bList.size(); } public boolean isEmpty() { ... } public boolean contains(Book b) { ... } public boolean add(Book b) { ... } public boolean remove(Book b) { .. } public void clear() { ... } public Object get(int index) { ... } } In my main class I want to print titles of books with in a for each loop: for(Book b : bList) { b.print(); } Eclipse says: Can only iterate over an array or an instance of java.lang.Iterable How can

Iterables present two methods for getLast public static <T> T getLast(Iterable<T> iterable); public static <T> T getLast(Iterable<T> iterable, @Nullable T defaultValue); but only one for getFirst public static <T> T getFirst(Iterable<T> iterable, @Nullable T defaultValue); Is there are any design/implementation reason for breaking symmetry? John B I think the point is that there is no reason for a getFirst(iterable) in that this could be done with iterable.iterator().next() . Guava makes an excellent attempt to keep the API small and so does not add things that could / should be done easily

This question already has an answer here: Why does Iterable<T> not provide stream() and parallelStream() methods? 3 answers In Java 8, the Stream class does not have any method to wrap a an Iterable . Instead, I am obtaining the Spliterator from the Iterable and then obtaining a Stream from StreamSupport like this: boolean parallel = true; StreamSupport.stream(spliterator(), parallel) .filter(Row::isEmpty) .collect(Collectors.toList()) .forEach(this::deleteRow); Is there some other way of generating Stream operations on an Iterable that I am missing? My similar question got marked as duplicate

What's the shortest way to get first item of OrderedDict in Python 3? My best: list(ordered_dict.items())[0] Quite long and ugly. I can think of: next(iter(ordered_dict.items())) # Fixed, thanks Ashwini But it's not very self-describing. Any better suggestions? Programming Practices for Readabililty In general, if you feel like code is not self-describing, the usual solution is to factor it out into a well-named function: def first(s): '''Return the first element from an ordered collection or an arbitrary element from an unordered collection. Raise StopIteration if the collection is empty. '''

Possible Duplicate: Why is Java's Iterator not an Iterable? Idiomatic way to use for-each loop given an iterator? Can we use for-each loop for iterating the objects of Iterator type? The foreach loop are as far as I know syntax sugar added in Java 5. So Iterable<O> iterable; for(O o : iterable) { // Do something } will essentially produce the same bytecode as Iterable<O> iterable; for(Iterator<O> iter = iterable.iterator(); iter.hasNext(); /* NOOP */) { O o = iter.next(); // Do something } However, if I do not have an iterable in the first place, but only an iterator (say, because a class

I need to figure out the number of elements in an Iterable in Java. I know I can do this: Iterable values = ... it = values.iterator(); while (it.hasNext()) { it.next(); sum++; } I could also do something like this, because I do not need the objects in the Iterable any further: it = values.iterator(); while (it.hasNext()) { it.remove(); sum++; } A small scale benchmark did not show much performance difference, any comments or other ideas for this problem? TL;DR: Use the utility method Iterables.size(Iterable) of the great Guava library. Of your two code snippets, you should use the first one,

Given: x = ['w', 'e', 's', 's', 's', 'z','z', 's'] Each occurrence of s appears at the following indices: 1st: 2 2nd: 3 3rd: 4 4th: 7 If I do x.index('s') I will get the 1st index. How do I get the index of the 4th s ? Using list comprehension and enumerate : >>> x = [ 'w', 'e', 's', 's', 's', 'z','z', 's'] >>> [i for i, n in enumerate(x) if n == 's'][0] 2 >>> [i for i, n in enumerate(x) if n == 's'][1] 3 >>> [i for i, n in enumerate(x) if n == 's'][2] 4 >>> [i for i, n in enumerate(x) if n == 's'][3] 7 If you didn't want to store the indices for each occurrence, or wanted to work with

I'm trying to run a for loop. Here's the section of my code I'm having trouble with: aldurstengd_ororka = {(18, 19, 20, 21, 22, 23, 24):1, (25):0.95, (26):0.90, (27):0.85, (28, 29):0.75, (30, 31):0.65, (32, 33):0.55, (34, 35):0.45, (36, 37):0.35, (40, 41, 42, 43, 44, 45):0.15, (46, 47, 48, 49, 50):0.10, (51, 52, 53, 54, 55):0.075, (56, 57, 58, 59, 60):0.05, (61, 62, 63, 64, 65, 66):0.025} for age in aldurstengd_ororka.keys(): for item in age: if ororkualdur == item: baetur = baetur + ororkulifeyrir * aldurstengd_ororka([age]) So my intention is to run through aldurstengd_ororka, and for each