Java regex replace values

Question

I am trying to replace certain values from a string using java regex

for example the string looks like

:20:1234
    6789
:28G::xyz
|20:3456
    1234
|29C:pqr
:20|9876 

I want to replace tag 20 value (may be multi line value) for second occurrence

|20:3456
    1234

with new value(may be multi line value) 6789 so the final replacement string i am expecting is

:20:1234
    6789
:28G::xyz
|20:6789
|29C:pqr
:20|9876 

Answer 1

这应该工作（测试）：

str.replaceAll("(\\|" + "20" + ":)[^|:]*\n","$1" + "6789" + "\n");

Answer 2

Try this regex:

String str = ":20:1234\n    6789\n:28G::xyz\n|20:3456\n    1234\n|29C:pqr\n:20|9876 \n|20:3456\n    :20:1234\n";
str = str.replaceAll("(\\|20:)[\\s\\S]*?(?=[|:])","$1" + "6789\n");

Here it is checking until it reaches to anything other than | or : , so that it doesn't pick all.