StateTree.java 文件源码

/**
 * Retrieves the child of a given parent node that is
 * a numbered tree node with a given number, if any.
 * @return the correctly numbered child, or {@code null} if there
 * is none such
 */
private NumberedTreeNode find(TreeNode parent, int number) {
    NumberedTreeNode result = null;
    int lower = 0;
    int upper = parent.getChildCount() - 1;
    boolean found = false;
    while (!found && lower <= upper) {
        int mid = (lower + upper) / 2;
        result = (NumberedTreeNode) parent.getChildAt(mid);
        int resultNumber = result.getNumber();
        if (result.contains(number)) {
            found = true;
        } else if (resultNumber < number) {
            lower = mid + 1;
        } else if (resultNumber > number) {
            upper = mid - 1;
        }
    }
    return found ? result : null;
}