如何使用IndexOf和substring Java从字符串中提取多个单词？

Question

我有一个通过系统导入的文件，现在卡住了。 使用while循环和if语句，并且没有Split（）方法的帮助，我如何首先与扫描器逐行读取文件？ 然后第二个，我该如何一个个地拔出单词，当我拔出一个单词时，一个变量，countWords必须加一，说一个字符串中有5个单词，我需要遍历循环5次，然后countWords将变为5。这是我到目前为止的代码，有点Kin脚。

import java.util.Scanner;
import java.io.*;

class Assignmentfive
{
private static final String String = null;

 public static void main(String[] args) throws              FileNotFoundException
 {
 Scanner scan = new Scanner(new File("asgn5data.txt"));

int educationLevel = 0;
String fileRead = "";
int wordCount = 0;

while (scan.hasNext() && !fileRead.contains("."))
{
  fileRead = scan.nextLine();

  int index = fileRead.indexOf(" ");
  String strA = fileRead.substring(index);

  System.out.print(strA);
  wordCount++;

 }

我的代码有更多内容，但是仅注释掉了一些计算。 谢谢！

Answer 1

这是我重构您的while循环以正确提取，打印和计算句子中所有单词的方式：

while (scan.hasNext()) {
    int wordCount = 0;
    int numChars = 0;
    fileRead = scan.nextLine();

    // Note: I add an extra space at the end of the input sentence
    //       so that the while loop will pick up on the last word.
    if (fileRead.charAt(fileRead.length() - 1) == '.') {
        fileRead = fileRead.substring(0, fileRead.length() - 1) + " ";
    }
    else {
        fileRead = fileRead + " ";
    }
    int index = fileRead.indexOf(" ");
    do {
        String strA = fileRead.substring(0, index);
        System.out.print(strA + " ");
        fileRead = fileRead.substring(index+1, fileRead.length());
        index = fileRead.indexOf(" ");
        wordCount++;
        numChars += strA.length();
    } while (index != -1);

    // here is your computation.
    if (wordCount > 0) {
        double result = (double)numChars / wordCount;  // average length of words
        result = Math.pow(result, 2.0);                // square the average
        result = wordCount * result;                   // multiply by number of words
        System.out.println(result);                    // output this number
    }
}

我通过硬编码字符串fileRead来测试此代码，这是您的第一句话The cat is black. 。 我得到以下输出。

输出：

The
cat
is
black