How to replace particular substring using regular expression using java?

Question

I have a string as below.

$Trap:com.oss.Event(description  matches  "abc")

In the above string the generic portions is $Trap:com.oss.Event(<Any string>).

when i encounter the above string i need to replace with the below string.

$Trap:com.oss.Event(description  matches  "abc") from entry-point "EventStream".

To achieve the above i am using the following logic in java.

String stmt= $Trap:com.oss.Event(description  matches  "abc")

if(stmt.matches(".*\\.Event(.*).*")&& s.equals(""))
{
                stmt+=" from entry-point "+"ABCStream";
}

But the above logic is not working as expected when the string is as below.

stmt="$Trap:com.oss.Event(description matches "abc") or $Trap:com.oss.Event(description matches  "cde");

I need to generate the following corresponding string using regular expression.

$Trap:com.oss.Event(description matches "abc") from entry-point "ABCStream" or $Trap:com.oss.Event(description matches  "cde") from entry-point "ABCStream"

Please provide some pointers to achieve the same.

can't you just use String.Replace?

Oliver
– Oliver

2011-09-29 15:11:40 +00:00
Commented Sep 29, 2011 at 15:11 — Oliver
– Oliver, Commented Sep 29, 2011 at 15:11

greuze · Accepted Answer · 2011-09-29 15:22:18Z

2

This do the stuff:

public class A {
    public static void main(String[] args) {
        String stmt="$Trap:com.oss.Event(description matches \"abc\") or $Trap:com.oss.Event(description matches  \"cde\")";
        System.out.println(stmt);
        System.out.println(stmt.replaceAll("(\\$Trap:com.oss.Event\\([^)]*\\))", "$1 from entry-point \"ABCStream\""));
    }
}

As you can see, you must double escape some symbols. The first and last parenthesis are for grouping the regex, and you can print that group with "$1"

And procuded this output:

$Trap:com.oss.Event(description matches "abc") or $Trap:com.oss.Event(description matches  "cde")
$Trap:com.oss.Event(description matches "abc") from entry-point "ABCStream" or $Trap:com.oss.Event(description matches  "cde") from entry-point "ABCStream"

answered Sep 29, 2011 at 15:22

greuze

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Comments

Eugene Kuleshov · Accepted Answer · 2011-09-29 15:27:19Z

2

The following Java code works:

String stmt = "$Trap:com.oss.Event(description matches \"abc\")"
   + " or $Trap:com.oss.Event(description matches  \"cde\")";

Pattern p = Pattern.compile(".*?\\.Event\\(.*?\\)");
String res = p.matcher(stmt).replaceAll("$0 from entry-point \"ABCStream\"");

System.err.println(res);

and produces the following result:

$Trap:com.oss.Event(description matches "abc") from entry-point "ABCStream" or $Trap:com.oss.Event(description matches  "cde") from entry-point "ABCStream"

You need to quote special chars, e.g. round brackets, inside regexp and also use lazy match, i.e. *?. The $0 refers to the found matching group.

Using Pattern.compile() will save you some performance, if you are doing this replacement repeatedly.

edited Sep 29, 2011 at 15:27

answered Sep 29, 2011 at 15:11

Eugene Kuleshov

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