从文件中扫描Java中的每个字符

Question

I have a program which scans a text file and identifies whether or not each line starts with a vowel, however, I need to be able to scan each character to determine whether or not there are any vowels on the line and not just at the start.

String x = "";
Set<String> vowells = new HashSet<>();
vowells.add("a");
vowells.add("e");
vowells.add("i");
vowells.add("o");
vowells.add("u");

while (sc.hasNextLine()) {

          readLine = new Scanner(sc.nextLine());
          x = readLine.nextLine();
          numberOfLines++;  



          if(vowells.contains(x.toLowerCase())) { 

          numberOfVowells++;


      }
    }

I have tried using while sc.hasNext and tried using splitregex but I have had no luck so I thought maybe my error is something small and someone here could help me?

Answer 1

The question seems a little confusing, but if you are trying to just find vowels in the file, you can do it line by line. Here's some example code:

    int numberOfVowells = 0;
    String x = "";
    String letter = "";
    Set<String> vowells = new HashSet<>();
    vowells.add("a");
    vowells.add("e");
    vowells.add("i");
    vowells.add("o");
    vowells.add("u");
    File myFile = new File("Hello.txt");
    Scanner sc = new Scanner(myFile);

    while(sc.hasNextLine())
    {
       //take it in line by line
       x = sc.nextLine();
       //cycle through each character in the line
       for(int i = 0; i < x.length(); i++)
       {
           letter = x.substring(i,i);
           if(vowells.contains(letter.toLowerCase()))
           {
               numberOfVowells++;
           }
       }
    }

I suppose if you wanted to count number of lines starting with vowels you could just add an if statement for when i is zero and it is a vowel.

Answer 2

You only have to use one Scanner to read the file.

File file = new File("the/path/to/your/file");
Scanner scanner = new Scanner(file);   

Then you can use hasNextLine() and nextLine() to read the contents of your file line by line

String currLine;
while(scanner.hasNextLine()) {
    currLine = scanner.nextLine();
    //do something with currLine
}

In your case is seems you want to check if the current line starts with a vowel, so I would recommend first make the currLine all lowercase and trimmed.

currLine = currLine.toLowerCase().trim();

Then you can use String functions like startsWith and charAt to do your checks.

Answer 3

Scanner filescan = new Scanner(new File("**your document/file**"));