算法-二分查找

今天在看 SparseArray 源码的时候看到了很多地方都用到了 ContainerHelpers.binarySearch(mKeys, mSize, key) 方法

ContainerHepler 类位于：android.util

源码：

    static int binarySearch(int[] array, int size, int value) {
        int lo = 0;
        int hi = size - 1;

        while (lo <= hi) {
            final int mid = (lo + hi) >>> 1;
            final int midVal = array[mid];

            if (midVal < value) {
                lo = mid + 1;
            } else if (midVal > value) {
                hi = mid - 1;
            } else {
                return mid;  // value found
            }
        }
        return ~lo;  // value not present
    }