Android Question Regular Expression in b4A to highlight a pattern word anywhere in a string

Pattern: "rail"

Erel said:

[B4X] CSBuilder marking based on regex pattern

CSBuilder is supported by B4A and B4J. There are some differences in the supported properties. A more powerful cross platform alternative: [B4X] BCTextEngine / BBCodeView - Text engine + BBCode parser + Rich Text View This sub searches for matches and uses CSBuilder to mark the matches...

www.b4x.com

Pattern: "rail"

Click to expand...

What the, 2017 @Erel, where on earth did that post come from, and how did I somehow missed it

That's an excellent solution that I never even knew already existing. Thank you for sharing, again ?

Hi Erel !

Sorry... But I am unable to make it work... Attaching the source code ... I am getting the following error. Also pasted your calling code example string.
Please help.

Thanks..

:BEGIN ERROR:
Logger connected to: ......
--------- beginning of main
*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
main_markpattern (java line: 422)
java.lang.ArrayIndexOutOfBoundsException: length=2; index=2
at java.util.regex.Matcher.start(Matcher.java:1159)
at anywheresoftware.b4a.keywords.Regex$MatcherWrapper.GetStart(Regex.java:174)
at b4a.example.main._markpattern(main.java:422)
at b4a.example.main._activity_create(main.java:367)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:213)
at b4a.example.main.afterFirstLayout(main.java:105)
at b4a.example.main.access$000(main.java:17)
at b4a.example.main$WaitForLayout.run(main.java:83)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:201)
at android.app.ActivityThread.main(ActivityThread.java:6823)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)
*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
main_markpattern (java line: 422)
java.lang.ArrayIndexOutOfBoundsException: length=2; index=2
at java.util.regex.Matcher.start(Matcher.java:1159)
at anywheresoftware.b4a.keywords.Regex$MatcherWrapper.GetStart(Regex.java:174)
at b4a.example.main._markpattern(main.java:422)
at b4a.example.main._activity_create(main.java:367)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:213)
at b4a.example.main.afterFirstLayout(main.java:105)
at b4a.example.main.access$000(main.java:17)
at b4a.example.main$WaitForLayout.run(main.java:83)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:201)
at android.app.ActivityThread.main(ActivityThread.java:6823)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)

:END ERROR:

The group number in the first pattern is wrong.
It should be:

Erel said:

The group number in the first pattern is wrong.
It should be:

B4X:

Dim cs1 As CSBuilder = MarkPattern(s1, "Rail", 0)
Dim cs2 As CSBuilder=MarkPattern(s2,"\B(#\w+)\b",1)

Click to expand...

Thanks Erel !

It worked ! .. I also changed the pattern to (?i)(rail) (so it can be case insensitive match)..Hope it is correct ..

However, did not understand the purpose of Group Number..

Thanks..