Java迭代器实现Python中的range代码实例

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

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;
    }
  }
}