(Count the occurrences of words in a text file) Rewrite Listing 21.9 to read the text from a text file. The text file is passed
as a command-line argument. Words are delimited by whitespace characters, punctuation marks (, ; . : ?), quotation marks (' "), and parentheses. Count the words in a case-sensitive fashion (e.g., consider Good and good to be the same word). The words must start with a letter. Display the output of words in alphabetical order, with each word preceded by the number of times it occurs. I ran my version of the program solution on its own Java source file to produce the following sample output:
C:\Users\......\Desktop>java CountOccurrenceOfWords CountOccurrenceOfWords.java
Display words and their count in ascending order of the words
1 a
1 alphabetical
1 an
2 and
3 args
2 as
1 ascending
1 catch
1 class
4 count
2 countoccurrenceofwords
1 create
1 display
1 else
3 entry
3 entryset
2 ex
1 exception
1 exit
1 file
2 filename
3 for
1 fullfilename
3 get
1 getkey
1 getvalue
1 hasnext
1 hold
5 i
3 if
2 import
2 in
3 input
2 int
1 io
3 java
6 key
3 length
2 line
1 main
3 map
1 matches
3 new
1 nextline
1 null
1 of
2 order
3 out
3 println
1 printstacktrace
2 public
2 put
2 scanner
1 set
1 split
1 static
5 string
4 system
2 the
1 their
1 to
1 tolowercase
2 tree
6 treemap
2 trim
1 try
1 util
1 value
1 void
1 while
9 words
C:\Users\......\Desktop>
The following is written in Java. It uses File input, to get the file and read every line in the file. It adds all the lines into a variable called fullString. Then it uses regex to split the string into separate words. Finally, it maps the words into an array that counts all the words and how many times they appear. A test case has been created and the output can be seen in the attached image below. Due to technical difficulties I have added the code as a txt file below.
