Using the Java implementation of the Python iterators in the range

If you want an iteration object of a class, the class must implement the Iterable interface, and then returns a Iterator instance by the iterator method.

Range Python class implements all of the usage range, such as: range (10), range (5, 10), range (10, 0, -1), range (0, 10, 2)

If we define a static factory method in the Range class, and then introduced into a static factory method, it is easier to use.

Example:

for (int X: the Range new new (10, 0, -1)) { 
    System.out.println (X); 
} 
/ * output: 
10 
. 9 
. 8 
. 7 
. 6 
. 5 
. 4 
. 3 
2 
. 1 
* /

　　

Code:

class Range implements Iterable<Integer> {
    private final int start;
    private final int end;
    private final int step;

    public Range(int end) {
        this(0, end, 1);
    }

    public Range(int start, int end) {
        this(start, end, 1);
    }

    public Range(int start, int end, int step) {
        this.start = start;
        this.end = end;
        this.step = step;
    }

    @Override
    public Iterator<Integer> iterator() {
        return new Itr();
    }
    private class Itr implements Iterator<Integer> {
        int current = start;
        @Override
        public boolean hasNext() {
            return step > 0 ? current < end : current > end;
        }

        @Override
        public Integer next() {
            int t = current;
            current += step;
            return t;
        }
    }
}