This tutorial will teach you how to create a program that will have an example of Caret Event and Listener in Java. A CaretEvent lets the user notify interested parties that the text caret has changed in the event with its source. Note: A caret is the cursor indicating the insertion point

So, now let's start this tutorial!

1. Open JCreator or NetBeans and make a java program with a file name of countSubStrings.java.

2. Import the io package library:

1. import
   
   java.io.*
   
   ;
   

3. Now, create a method named isEmpty as Boolean that has a String str as parameter. This will trigger to return 0 if the string doesn't have a substring inputted by the user.

1. public
   
   static
   
   boolean
   
   isEmpty(
   
   String
   
   str)
   
   {
   
2. return
   
   str ==
   
   null
   
   ||
   
   str.length
   
   (
   
   )
   
   ==
   
   0
   
   ;
   
3. }
   

4. Create again another method named countMatches that has the parameters of String str, String sub that will trigger to count how may substring are there in the inputted string.

1. public
   
   static
   
   int
   
   countMatches(
   
   String
   
   str, String
   
   sub)
   
   {
   
2. if
   
   (
   
   isEmpty(
   
   str)
   
   ||
   
   isEmpty(
   
   sub)
   
   )
   
   {
   
3. return
   
   0
   
   ;
   
4. }
   
5. int
   
   count =
   
   0
   
   ;
   
6. int
   
   idx =
   
   0
   
   ;
   
7. while
   
   (
   
   (
   
   idx =
   
   str.indexOf
   
   (
   
   sub, idx)
   
   )
   
   !=
   
   -
   
   1
   
   )
   
   {
   
8. count++;
   
9. idx +=
   
   sub.length
   
   (
   
   )
   
   ;
   
10. }
    
11. return
    
    count;
    
12. }
    

5. Now in your Main, create two String variables named string1,string2, and in variable for the inputting. Then get the input from the user.

1. BufferedReader
   
   in =
   
   new
   
   BufferedReader
   
   (
   
   new
   
   InputStreamReader
   
   (
   
   System
   
   .in
   
   )
   
   )
   
   ;
   
2. String
   
   string1,string2;
   
3. 
   
4. System
   
   .out
   
   .print
   
   (
   
   "Enter large string:"
   
   )
   
   ;
   
5. string1 =
   
   in.readLine
   
   (
   
   )
   
   ;
   
6. System
   
   .out
   
   .print
   
   (
   
   "Enter substring:"
   
   )
   
   ;
   
7. string2 =
   
   in.readLine
   
   (
   
   )
   
   ;
   

To display the number of strings in the large string, have this code below:

1. System
   
   .out
   
   .print
   
   (
   
   "Number of substrings found: "
   
   +
   
   countMatches(
   
   string1,string2)
   
   )
   
   ;
   

Output:


Here's the full code of this tutorial:

1. import
   
   java.io.*
   
   ;
   
2. public
   
   class
   
   countSubStrings {
   
3. public
   
   static
   
   void
   
   main(
   
   String
   
   args[
   
   ]
   
   )
   
   throws
   
   IOException
   
   {
   
4. BufferedReader
   
   in =
   
   new
   
   BufferedReader
   
   (
   
   new
   
   InputStreamReader
   
   (
   
   System
   
   .in
   
   )
   
   )
   
   ;
   
5. String
   
   string1,string2;
   
6. 
   
7. System
   
   .out
   
   .print
   
   (
   
   "Enter large string:"
   
   )
   
   ;
   
8. string1 =
   
   in.readLine
   
   (
   
   )
   
   ;
   
9. System
   
   .out
   
   .print
   
   (
   
   "Enter substring:"
   
   )
   
   ;
   
10. string2 =
    
    in.readLine
    
    (
    
    )
    
    ;
    
11. 
    
12. System
    
    .out
    
    .print
    
    (
    
    "Number of substrings found: "
    
    +
    
    countMatches(
    
    string1,string2)
    
    )
    
    ;
    
13. }
    
14. public
    
    static
    
    boolean
    
    isEmpty(
    
    String
    
    str)
    
    {
    
15. return
    
    str ==
    
    null
    
    ||
    
    str.length
    
    (
    
    )
    
    ==
    
    0
    
    ;
    
16. }
    
17. public
    
    static
    
    int
    
    countMatches(
    
    String
    
    str, String
    
    sub)
    
    {
    
18. if
    
    (
    
    isEmpty(
    
    str)
    
    ||
    
    isEmpty(
    
    sub)
    
    )
    
    {
    
19. return
    
    0
    
    ;
    
20. }
    
21. int
    
    count =
    
    0
    
    ;
    
22. int
    
    idx =
    
    0
    
    ;
    
23. while
    
    (
    
    (
    
    idx =
    
    str.indexOf
    
    (
    
    sub, idx)
    
    )
    
    !=
    
    -
    
    1
    
    )
    
    {
    
24. count++;
    
25. idx +=
    
    sub.length
    
    (
    
    )
    
    ;
    
26. }
    
27. return
    
    count;
    
28. }
    
29. 
    
30. 
    
31. }
    

For more inquiries and need programmer for your thesis systems in any kind of programming languages, just contact my number below.

Best Regards,

Engr. Lyndon Bermoy
IT Instructor/System Developer/Android Developer/Freelance Programmer
Mobile: 09488225971
Landline: 826-9296
E-mail:[email protected]

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