public class IteratorTest {
public static void main(String[] args) {
test();
}
public static void test() {
final Function<String, Iterable<String>> function = new Function<String, Iterable<String>>() {
@Override
public Iterable<String> apply(final String input) {
return new Iterable<String>() {
@Override
public Iterator<String> iterator() {
return new AbstractIterator<String>() {
int start = 0;
int end = input.length();
@Override
protected String computeNext() {
if (start > end - 1) {
return endOfData();
}
return String.valueOf(input.charAt(start++));
}
};
}
};
}
};
List<String> names = Lists.newArrayList("123", "456", "789", "abc");
Function<List<String>, Iterable<Iterable<String>>> fun = new Function<List<String>, Iterable<Iterable<String>>>() {
@Override
public Iterable<Iterable<String>> apply(final List<String> input) {
return new Iterable<Iterable<String>>() {
@Override
public Iterator<Iterable<String>> iterator() {
return new AbstractIterator<Iterable<String>>() {
int size = 0;
@Override
protected Iterable<String> computeNext() {
if (size > input.size() - 1) {
return endOfData();
}
Iterable<String> apply = function.apply(input.get(size++));
Preconditions.checkNotNull(apply);
return apply;
}
};
}
};
}
};
Function<Iterable<Iterable<String>>, Iterable<String>> convert = new Function<Iterable<Iterable<String>>, Iterable<String>>() {
@Override
public Iterable<String> apply(final Iterable<Iterable<String>> iterators) {
return new Iterable<String>() {
@Override
public Iterator<String> iterator() {
return new AbstractIterator<String>() {
Iterator<Iterable<String>> outerIterator = iterators.iterator();
Iterator<String> innerIterator = null;
@Override
protected String computeNext() {
if (innerIterator == null) {
if (!outerIterator.hasNext()) {
return endOfData();
}
innerIterator = outerIterator.next().iterator();
}
while (innerIterator.hasNext()) {
return innerIterator.next();
}
innerIterator = null;
return computeNext();
}
};
}
};
}
};
//每次外部的iterator便利一次就回不去了，所以为了每次获取到都是从0开始的，需要包一层
Function<Iterator<String>, Iterable<String>> con = new Function<Iterator<String>, Iterable<String>>() {
@Override
public Iterable<String> apply(final Iterator<String> input) {
return new Iterable<String>() {
@Override
public Iterator<String> iterator() {
return new AbstractIterator<String>() {
Iterator<String> inner = input;
@Override
protected String computeNext() {
while (inner.hasNext()) {
return inner.next();
}
return endOfData();
}
};
}
};
}
};
Iterable<Iterable<String>> res = fun.apply(names);
Iterable<String> iterators = convert.apply(res);
for(String name:iterators){
System.out.println(name);
}
System.out.println(Iterables.size(iterators));
//直接转换
Iterables.concat(res);
}
public void test2() {
Function<String, Iterable<String>> function = new Function<String, Iterable<String>>() {
@Override
public Iterable<String> apply(final String input) {
return new Iterable<String>() {
@Override
public Iterator<String> iterator() {
return new AbstractIterator<String>() {
int start = 0;
int end = input.length();
@Override
protected String computeNext() {
if (start > end - 1) {
return endOfData();
}
return String.valueOf(input.charAt(start++));
}
};
}
};
}
};
Iterable<String> aa = function.apply("12345");
Preconditions.checkNotNull(aa);
for (String a : aa) {
System.out.println(a);
}
Iterable<String> bb = Iterables.filter(aa, new Predicate<String>() {
@Override
public boolean apply(String input) {
return !StringUtils.equals(input, "5");
}
});
Iterable<String> cc = Iterables.concat(aa, bb);
Preconditions.checkNotNull(cc);
}
}