我正在尝试在 Java 中实作递回二进制搜索算法。

我正在有序的字符串阵列中寻找一个字符串。

为什么我得到 ArrayIndexOutOfBoundsException 输入“eeeeee”，而不是“eeeeee”？

先感谢您。

import java.util.Scanner;

class binarySearch{
    public static boolean recursiveBinarySearch(String[] arr, String searchTerm, int start, int end){
        int middle = start   (end-start)/2;
        if(start > end){
            return false;
        }

        if(arr[middle].equals(searchTerm)){
            return true;
        } else if(arr[middle].compareTo(searchTerm) > 0){
            return recursiveBinarySearch(arr, searchTerm, start, middle-1);
        } else if(arr[middle].compareTo(searchTerm) < 0){
            return recursiveBinarySearch(arr, searchTerm, middle 1, end);
        }
        return false;
    }

    public static void main(String[] args){

        Scanner console = new Scanner(System.in);
        String[] saved = {"aaaa","bbbb","cccc","ddddd","eeeee"};
        String searchTerm = "";
        do{
            System.out.println("Term to search in the ordered array:");
            searchTerm = console.nextLine();
        } while(searchTerm.equals(""));
        console.close();
        if(recursiveBinarySearch(saved, searchTerm, 0, saved.length)){
            System.out.println("Term found!");
        } else {
            System.out.println("Term NOT found!");
        }
    }
}

uj5u.com热心网友回复：

你end以saved.length. 这里的问题是，.length它将为您提供从 开始计数的长度1，而阵列与0.

只需saved.length-1像in一样end输入recursiveBinarySearch，就可以了！

import java.util.Scanner;

class binarySearch{
    public static boolean recursiveBinarySearch(String[] arr, String searchTerm, int start, int end){
        int middle = start   (end-start)/2;
        if(start > end){
            return false;
        }

        if(arr[middle].equals(searchTerm)){
            return true;
        } else if(arr[middle].compareTo(searchTerm) > 0){
            return recursiveBinarySearch(arr, searchTerm, start, middle-1);
        } else if(arr[middle].compareTo(searchTerm) < 0){
            return recursiveBinarySearch(arr, searchTerm, middle 1, end);
        }
        return false;
    }

    public static void main(String[] args){

        Scanner console = new Scanner(System.in);
        String[] saved = {"aaaa","bbbb","cccc","ddddd","eeeee"};
        String searchTerm = "";
        do{
            System.out.println("Term to search in the ordered array:");
            searchTerm = console.nextLine();
        } while(searchTerm.equals(""));
        console.close();
        if(recursiveBinarySearch(saved, searchTerm, 0, saved.length-1)){
            System.out.println("Term found!");
        } else {
            System.out.println("Term NOT found!");
        }
    }
}  

uj5u.com热心网友回复：

阵列索引从 0 到 4，您将其传递给 save.length，它的值为 5。它不会因“eeeee”而失败，因为代码在到达错误之前找到了阵列中的项目。将行更改为 saved.length-1。