如何使用IndexOf和substring Java從字符串中提取多個單詞？

Question

我有一個通過系統導入的文件，現在卡住了。 使用while循環和if語句，並且沒有Split（）方法的幫助，我如何首先與掃描器逐行讀取文件？ 然后第二個，我該如何一個個地拔出單詞，當我拔出一個單詞時，一個變量，countWords必須加一，說一個字符串中有5個單詞，我需要遍歷循環5次，然后countWords將變為5。這是我到目前為止的代碼，有點Kin腳。

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++;

 }

我的代碼有更多內容，但是僅注釋掉了一些計算。 謝謝！

Answer 1

這是我重構您的while循環以正確提取，打印和計算句子中所有單詞的方式：

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
    }
}

我通過硬編碼字符串fileRead來測試此代碼，這是您的第一句話The cat is black. 。 我得到以下輸出。

輸出：

The
cat
is
black