如何找到一个数被包含在数量的数组范围在java中 [英] How to find if a number is contained in an array of number ranges in java

问题描述

我的Java对象的数组。

I have an array of java objects.

• 每个对象存储定义一个数字范围内的两个多头。


• 我已经有一个保证，在范围内的所有对象，数量范围不重叠。

我想快速查找阵列中的特定对象的，给定其可以（或可以不）落在数中的一个内的范围由对象定义的一个数。

I want a quick of finding a particular object in the array, given a number which may (or may not) fall within one of the number ranges defined by the objects.

我希望能做到这一点使用Array.binarySearch但看起来并不合适。

I was hoping to do this using Array.binarySearch but that doesn't look appropriate.

在做到这一点的最佳方式有什么想法？

Any thoughts on the best way to do this?

推荐答案

使用TreeMap中。最关键的是两个长域范围的较低;该值是对象

Use a TreeMap. The key is the lower of the two Long range bounds; the value is the object.

private TreeMap<Long, T> map = new TreeMap<Long, T>();

void insertObject(T object) {
    map.put(object, object.getLowerRangeBoundary());
}

T getObjectByKeyInRange(Long query) {
    // Get the first Object in the tree that corresponds with the query
    Map.Entry<Long, T> e = map.floorEntry(query);

    // If there's no entry, then the query value is lower than all ranges in the tree
    if (e == null) {
        return null;
    }

    T target = e.getValue();
    // "target" is the only object that can contain the query value
    // If the query value is within the range of "target", then it is our object
    if (query < target.getUpperRangeBoundary()) {
        return target;
    }

    // Nobody has the query value in their range; return null
    return null;
}

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