如何让这个循环工作？文件未解决[重复]

Question

我有这个片段，我想知道如何遍历这个文件的令牌。正如你们所见，我用扫描仪读了一遍，我把infle当成了未解析的。这是可以理解的，因为infle是一个扫描仪，我的意思是，一个对象，但我该如何使循环遍历文件？其思想是读取包含多个单词的文件内容，将每个单词转换为小写，并将其全部放入哈希集中。

import java.io.File;
import java.util.*;

public class CheckSpelling{
    
    public static void main(String[] args) {
        //Create HashSet to store our data.
        HashSet<String> words = new HashSet<String>();
        
        try {
            //Read file words.txt
            Scanner filein = new Scanner (new File("/classes/s09/cs225/words.txt"));
                }
            catch(Exception e) {
                e.printStackTrace();
            }
        
        //While there exists another word next...
        while (filein.hasNext()) {
        //Go to next word 
            String tk = filein.next();
        //Convert that word into lower case... 
            tk.toLowerCase(); 
        //add the word to our collection of data. 
            words.add(tk);
            }    
        }
    }

您将其放入java类中，它将生成未解析的infle。请帮我克服这一点。如果您在复制异常时遇到问题，请告诉我。

提前谢谢。

Answer 1

您将infile变量设置为未解析，因为您在try catch中声明了它。该变量的范围只是try catch，您正在尝试在外部使用它。

下面的示例不会抛出该错误。

import java.io.File;
import java.util.*;

public class CheckSpelling{

public static void main(String[] args) {
    //Create HashSet to store our data.
    HashSet<String> words = new HashSet<String>();

    try {
        //Read file words.txt
        Scanner filein = new Scanner (new File("/classes/s09/cs225/words.txt"));
        //While there exists another word next...
        while (filein.hasNext()) {
            //Go to next word
            String tk = filein.next();
            //Convert that word into lower case...
            tk.toLowerCase();
            //add the word to our collection of data.
            words.add(tk);
        }
    }
    catch(Exception e) {
        e.printStackTrace();
    }


}
}

Answer 2

这就是解决办法：你只需要更正括号。

 public static void main(String[] args) {
            //Create HashSet to store our data.
            HashSet<String> words = new HashSet<String>();
    
            try {
                //Read file words.txt
                Scanner filein = new Scanner (new File("your path"));
                //While there exists another word next...
                while (filein.hasNext()) {
                    //Go to next word
                    String tk = filein.next();
                    //Convert that word into lower case...
                    tk.toLowerCase();
                    //add the word to our collection of data.
                    words.add(tk);
                }
            }
            catch(Exception e) {
                e.printStackTrace();
            }
    }