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

There are many ways. If you're reading the file line-by-line, you can using the method indexOf on the String class to search each line for the text. You'd need to call it repeatedly to move through the line looking for additional occurrences.

See documentation on indexOf at:

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

Answer 2

As I understand your question, if you are reading the text line after line you can use recursivity to count how many occurences of the word appear in the same line:

The following method counts how many times a word appears in the same line

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 );
    }

}

In order to keep track of the first occurence of my word in my file along with the number of occurence I created a WordInfo class like this:

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;
    }
}

Now I can create my searchWord method. I give him the word to look for, the fileName and a WordInfo object to fill as input parameters

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;
}

Here is an illustration and the result below

I have the following content in a file called DemoFile.txt

And I test the code using the following main method (I am looking for the word concept for example):

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());


    }


}

And I obtain the following results: