在Java中的标签之间提取字符串

Question

I have string like below

Msg_Begin
Some message1
Msg_End
Msg_Begin
Some message2
Msg_End
Msg_Begin
Some message3
Msg_End

And want to get the message between Msg_Begin and Msg_End in to the list like

[Some message1, Some message2, Some message3]

what is the best approach for this in Java.

Answer 1

String messages = originalString.replaceAll("Msg_Begin","");
String[] array = messages.split("Msg_End");
return Arrays.asList(array);

Just make sure that your messages do not contain Msg_Begin or Msg_End .

Answer 2

You can achieve that with a regular expression :

//Filling Your test case and print
String entry = "Msg_Begin\r\n" + 
               "Some message1\r\n" + 
               "Msg_End\r\n" + 
               "Msg_Begin\r\n" + 
               "Some message2\r\n" + 
               "Msg_End\r\n" + 
               "Msg_Begin\r\n" + 
               "Some message3\r\n" + 
               "Msg_End";

System.out.println("IN : \r\n" + entry) ;

//Compile the regular expression patern, providing the DOTALL flag to enable mutiline matches
Pattern p = Pattern.compile("Msg_Begin\r\n(.+?)\r\nMsg_End(\r\n)?", Pattern.DOTALL) ;  
Matcher m = p.matcher(entry) ; 

// iterate over results (for exemple add them to a list)
System.out.println("\r\nOUT :") ;
List<String> list = new ArrayList<>();
while (m.find()) {
    list.add( m.group(1));
    System.out.println(m.group(1)) ;
}

Produce the following result :

IN : 
Msg_Begin
Some message1
Msg_End
Msg_Begin
Some message2
Msg_End
Msg_Begin
Some message3
Msg_End

OUT :
Some message1
Some message2
Some message3

More informations abour regular expressions syntax can be found here