1+ /*********************************************************************************
2+ * (Count the occurrences of words in a text file) Rewrite Listing 21.9 to read *
3+ * the text from a text file. The text file is passed as a command-line argument. *
4+ * Words are delimited by whitespace characters, punctuation marks (,;.:?), *
5+ * quotation marks ('"), and parentheses. Count words in case-insensitive fashion *
6+ * (e.g., consider Good and good to be the same word). The words must start with *
7+ * a letter. Display the output in alphabetical order of words, with each word *
8+ * preceded by its occurrence count. *
9+ *********************************************************************************/
10+ import java .util .*;
11+ import java .io .*;
12+
13+ public class Exercise_21_08 {
14+ public static void main (String []args )throws Exception {
15+ // Check command-line argument length
16+ if (args .length !=1 ) {
17+ System .out .println ("Usage: java Exercise_21_08 textFileName" );
18+ System .exit (1 );
19+ }
20+
21+ // Check if the file exists
22+ File file =new File (args [0 ]);
23+ if (!file .exists ()) {
24+ System .out .println ("The file " +args [0 ] +" does not exists." );
25+ System .exit (1 );
26+ }
27+
28+ // Create a TreeMap to hold words as key and count as value
29+ Map <String ,Integer >map =new TreeMap <>();
30+
31+ try (// Create an input stream
32+ Scanner input =new Scanner (file );
33+ ) {
34+ while (input .hasNext ()) {
35+ String []words =input .nextLine ().split ("[\n \t \r \" \' .,;:!?()]" );
36+ store (map ,words );
37+ }
38+ }
39+
40+ // Get all entries into a set
41+ Set <Map .Entry <String ,Integer >>entrySet =map .entrySet ();
42+
43+ // Get key and value from each entry
44+ for (Map .Entry <String ,Integer >entry :entrySet )
45+ System .out .println (entry .getValue () +"\t " +entry .getKey ());
46+ }
47+
48+ /** Method Sotres occurrence of words */
49+ private static void store (Map <String ,Integer >map ,String []words ) {
50+ for (int i =0 ;i <words .length ;i ++) {
51+ String key =words [i ].toLowerCase ();
52+
53+ if (key .length () >0 &&Character .isLetter (key .charAt (0 ))) {
54+ if (!map .containsKey (key )) {
55+ map .put (key ,1 );
56+ }
57+ else {
58+ int value =map .get (key );
59+ value ++;
60+ map .put (key ,value );
61+ }
62+ }
63+ }
64+ }
65+ }
