Question

我正在开发一个项目，在该项目中，它从.txt文件中读取书名并将它们放入arraylist，然后将arraylist转换为数组，用户输入一个数字作为书籍参考编号，然后它进行线性搜索和二进制搜索以查找该书。我只是遇到了二进制搜索的代码问题，就我的二进制搜索知识而言，这就是我所放在一起的，所以我的二进制搜索代码有什么问题？

 int left = 0,right = bookList.length;
int int1;
int1 = Integer.parseInt(input);
while(left <= right){
    int middle = (right + left)/2;
    int compare = input.compareTo(bookList[middle].referenceNumber);
    if(compare == 0){
        Output2.setText("The book is " + bookList[middle].title);
    } else if(compare < int1){
        right = middle - 1;
        left = 0;
        if(compare == 0){
          Output2.setText("The book is " + bookList[middle].title);
        }
    } else if(compare > int1){
        right = bookList.length;
        left = middle + 1;
        if(compare == 0){
            Output2.setText("The book is " + bookList[middle].title);
        }
    }
    }

以下是我的书类和书单数组

public class Book{
String referenceNumber, title;

public Book(String _referenceNumber, String _title){
   referenceNumber = _referenceNumber;
   title = _title;
}
}

 ArrayList <Book> Books = new ArrayList <Book> ();
 Book [] bookList;

感谢您提供的任何帮助

Answer 1

缩小范围时，请勿将左侧设置为零或右侧设置为.length。你必须保留旧的值。

int left = 0,right = bookList.length;
int int1;
int1 = Integer.parseInt(input);
while(left <= right){
    int middle = (right + left)/2;
    int compare = input.compareTo(bookList[middle].referenceNumber);
    if(compare == 0){
        Output2.setText("The book is " + bookList[middle].title);
    } else if(compare < int1){
        right = middle - 1;
        if(compare == 0){
          Output2.setText("The book is " + bookList[middle].title);
        }
    } else if(compare > int1){
        left = middle + 1;
        if(compare == 0){
            Output2.setText("The book is " + bookList[middle].title);
        }
    }
    }

如何在java中进行二进制搜索？

1 个答案: