如何使用Java搜索用户确定的单词并计算文本文件中的出现次数？

Question

我已经到了可以读取文件并在文件中输出实际文本的地步，但是我不太确定如何继续搜索特定单词并显示单词数。

Answer 1

有很多方法。 如果要逐行读取文件，则可以使用String类上的indexOf方法在每一行中搜索文本。 您需要反复调用它以遍历该行以查找其他事件。

请参阅indexOf上的文档，位于：

http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#indexOf(java.lang.String,%20int）

Answer 2

据我了解您的问题，如果您正在逐行阅读文本行，则可以使用递归计算该行中出现该单词的次数：

以下方法计算单词在同一行中出现的次数

private static int numberOfLineOccurences;

public static int countNumberOfTimesInALine(String line, String word) {
    if (line.indexOf(word) == -1) {
        return numberOfLineOccurences;
    } else {
        numberOfLineOccurences++;
        if (line.indexOf(word) + word.length() >  line.length() -1     ) {
            return numberOfLineOccurences;
        }
        return countNumberOfTimesInALine(
                line.substring(line.indexOf(word) + word.length()), word );
    }

}

为了跟踪单词在文件中的首次出现以及出现的次数，我创建了一个WordInfo类，如下所示：

class WordInfo {

    private int firstOccurenceLineNumber;
    private int firstOccurenceColumnNumber;
    private String word;
    private int numberOfOccurences;

    public String getWord() {
        return word;
    }

    public int getNumberOfOccurences() {
        return numberOfOccurences;
    }

    public WordInfo(String word) {
        this.word = word;
    }

    public void upOccurrence() {
        numberOfOccurences++;
    }

   public void upOccurrence(int numberOfTimes) {
        numberOfOccurences+= numberOfTimes;
    }

   public int getFirstOccurenceLineNumber() {
    return firstOccurenceLineNumber;
    }

   public void setFirstOccurenceLineNumber(int firstOccurenceLineNumber) {
       this.firstOccurenceLineNumber = firstOccurenceLineNumber;
    }

   public int getFirstOccurenceColumnNumber() {
       return firstOccurenceColumnNumber;
    }

    public void setFirstOccurenceColumnNumber(int     firstOccurenceColumnNumber) {
        this.firstOccurenceColumnNumber = firstOccurenceColumnNumber;
    }
}

现在，我可以创建我的searchWord方法。 我给他寻找的单词，fileName和一个WordInfo对象作为输入参数填充

public static boolean searchWord(String word, String filePath, WordInfo wInfo) throws IOException {

    boolean result = false;
    boolean firstOccurenceFound = false;
    int lineNumber = 0;

    BufferedReader reader = new BufferedReader(new FileReader(new File(filePath)));
    String line = null;

    while ( (line = reader.readLine()) != null) {

        lineNumber++;

        numberOfLineOccurences= 0;

        if (line.indexOf(word) != -1) {
            if (!result) {
                result = true;
            }
            if (!firstOccurenceFound) {
                firstOccurenceFound = true;
                wInfo.setFirstOccurenceLineNumber(lineNumber);
                wInfo.setFirstOccurenceColumnNumber(line.indexOf(word) + 1);


            }
            wInfo.upOccurrence(countNumberOfTimesInALine(line, word));
        }


    }

    reader.close();

    return result;
}

这是一个例子，下面是结果

我在名为DemoFile.txt的文件中具有以下内容

然后，我使用以下主要方法测试代码（例如，我正在寻找单词concept ）：

public static void main(String[] args) throws IOException {
    WordInfo wInfo = new WordInfo("concept");
    if ( searchWord("concept", FILE_PATH, wInfo)) {
        System.out.println("Searching for " + wInfo.getWord());
        System.out.println("First line where found : " + wInfo.getFirstOccurenceLineNumber());
        System.out.println("First column found: " + wInfo.getFirstOccurenceColumnNumber());
        System.out.println("Number of occurrences " + wInfo.getNumberOfOccurences());


    }


}

并且我得到以下结果：