在java中设置的间隔

Question

我有一个带整数值的区间列表[例如.[1,4],[10,19]等].有没有办法将这些间隔放入一些java集合的容器中[例如.设置]这样我就可以在容器上调用'union'函数.'union'函数应该给我一个间隔列表,这样如果任何2个插入的间隔重叠,那么它们应该在输出中合并.我尝试在Guava中使用Range类,但最终在合并之前将所有间隔相互比较.一个优雅的方法将非常感谢!以下是我根据以下回答尝试的内容.输出为[[1,15],[17,20]],这是正确的.我想知道是否有一些现有的API实现了这样的东西.

public static void main(String[] args) {
    // mock data
    List<MyIntRange> rng_lst = new ArrayList<Junk.MyIntRange>();
    rng_lst.add(new MyIntRange(1, 10));
    rng_lst.add(new MyIntRange(5, 15));
    rng_lst.add(new MyIntRange(17, 20));

    // sort intervals by start position
    Collections.sort(rng_lst);

    // merge the intervals which overlap
    List<MyIntRange> res_lst = new ArrayList<Junk.MyIntRange>();
    MyIntRange old_rng = null;
    for (MyIntRange cur_rng : rng_lst) {
        if (old_rng == null) {
            old_rng = cur_rng;
        } else {
            if (old_rng.rng.upperEndpoint() < cur_rng.rng.lowerEndpoint()) {
                // this does not over lap with the next one
                res_lst.add(old_rng);
                old_rng = cur_rng;
            } else {
                // overlap
                old_rng = new MyIntRange(old_rng.rng.lowerEndpoint(),
                        cur_rng.rng.upperEndpoint());
            }
        }
    }
    // add the last range
    res_lst.add(old_rng);

    // done!
    System.out.println(res_lst);
}

// wrapper around Guava's Range to make it comparable based on the
// interval's start
public static class MyIntRange implements Comparable<MyIntRange> {
    Range<Integer> rng;

    public MyIntRange(int start, int end) {
        rng = Ranges.closed(start, end);
    }

    public int compareTo(MyIntRange that) {
        int res = -1;
        if (this.rng.lowerEndpoint() > that.rng.lowerEndpoint()) {
            res = 1;
        }
        return res;
    }

    public String toString() {
        return "[" + rng.lowerEndpoint() + ", " + rng.upperEndpoint() + "]";
    }
}

谢谢

Answer 1

这基本上就是RangeSet刚刚发布的Guava 14.0中的内容,除了它为你合并,而不是告诉你哪些范围可以合并.