How do I replace spaces with \n in java?

Question

Currently have

<?xml version="1.0" encoding="ISO-8859-1"?>  <entity>  <id>8624</id>  <name>Test_Report.csv</name>  <startDate>24/05/2021 9:15 am</startDate>  <level>info</level>  </entity>

I did:

message = messsage.replaceAll("\\s+","\\n")

This gives me:

<?xml version="1.0"\nencoding="ISO-8859-1"?>\n<entity>\n<id>8624</id>\n  <name>Test_Report.csv</name>\n<startDate>24/05/2021\n9:15 am</startDate>\n<level>info</level>\n </entity>

I want the output to keep the spaces in xml element data untouched and look like below:

<?xml version="1.0" encoding="ISO-8859-1"?>
<entity>
<id>8624</id>
<name>Test_Report.csv</name>
<startDate>24/05/2021 9:15 am</startDate>
<level>info</level>
</entity>

Answer 1

message = messsage.replaceAll("(?<=>)\\s*(?=<)","\n")

Answer 2

The correct regex should match only spaces between > and < characters, so it will look like this \>\s*?\< (it also will work when you don't have spaces between >< XML tags).

And a replacement string will be >\n<

Pay an attention that the second parameter for a String.replaceAll is a plain String, not a Regular Expression, so you don't need to escape it with backslashes \.

backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string. Dollar signs may be treated as references to captured subsequences, and backslashes are used to escape literal characters in the replacement string.

message.replaceAll("\\>\s*?\\<", ">\n<");

You can run it online here - https://www.mycompiler.io/view/1Bm8MzU

---

If your XML string is already formatted (i.e. has indentations with spaces), you can keep this indentation space characters by capturing them into the group \>(\s*?)\< and add a new line character before this group using >\n$1<.

message.replaceAll("\\>(\\s*?)\\<", ">\n$1<")

You can run it online here - https://www.mycompiler.io/view/5zaV7tf

Answer 3

String message = "<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?>  <entity>  <id>8624</id>  <name>Test_Report.csv</name>  <startDate>24/05/2021 9:15 am</startDate>  <level>info</level>  </entity>";
String result = message.replaceAll(">\\s*<", ">\n<");
System.out.println(result);

will match all the occurrences of zero or more spaces placed between > and < characters, and matched pattern will be then replaced with >\n<, outputting:

<?xml version="1.0" encoding="ISO-8859-1"?>
<entity>
<id>8624</id>
<name>Test_Report.csv</name>
<startDate>24/05/2021 9:15 am</startDate>
<level>info</level>
</entity>