Code to count a particular String in each line of a text file using Java 8 Stream

Question

I am new to the streams and I have the requirement to count a particular String in each line of a text file using Java 8 Stream. Does anyone have any suggestions or sample code? Edit: I missed to add my sample code..Here is the code I have just started but I have no clue as how to use count() on the stream.

Stream<String> lines=Files.lines(Paths.get("M:\\GIT_CODE\\FIRE_CHAT_PARSE\\New Text Document.txt"));

lines.map(eachLine-> spliteLineToArrayofSTrFunc(eachLine)).forEach(eachLines->{
        System.out.println(eachLines);  
        System.out.println();   
});
        
private static Function<String, String[]> spliteLineToArrayofSTrFunc(String line) {
        return (String lines)->{
            System.out.println();
            return line.split(" ");
        };
}

What have you tried so far? Please share your attempts and ask a more specific question. — Turing85
– Turing85, Commented Aug 22, 2020 at 15:11
Suggestion: Look for a terminal operation named count under the Stream class. But remember, you might want to filter specific string before you count. — Naman
– Naman, Commented Aug 22, 2020 at 15:14
Let's say you want to find the string lapse? Do you want the count to include the word collapse? What if the line includes the string more than once? You need to be specific in what you want. Perhaps show some examples. — WJS
– WJS, Commented Aug 22, 2020 at 15:52

Pankaj · Accepted Answer · 2020-08-22 16:16:39Z

1

If your question is about finding exact match with words separated by whitespace and also including words ending with . then you can do something like -

long count =
    strings.stream()
        .flatMap(str -> Arrays.stream(str.split("[\\s\\.]+")))
        .filter(str -> str.equals(wordToSearch))
        .count();

For below 2 lines, if you search for word stream then you'll get 3 as count.

I am new to the stream and I have the requirement to count a particular String in each line of a text file using Java 8 stream. 
Does anyone have any stream suggestions or sample code? Edit: I missed to add my sample code.

answered Aug 22, 2020 at 16:16

Pankaj

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1 Comment

Holger Over a year ago

You can avoid the temporary array created by split by using .flatMap(Pattern.compile("[\\s\\.]+" )::splitAsStream). This will also avoid compiling the regex pattern for every line.

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