Update README.md

johnA1331 · web-flow · commit 8c337801ce3f · 2021-12-01T16:33:28.000+08:00
diff --git a/core-java-modules/core-java-string-operations-4/README.md b/core-java-modules/core-java-string-operations-4/README.md
@@ -2,4 +2,5 @@
 
 - [Ignoring Commas in Quotes When Splitting a Comma-separated String](https://www.baeldung.com/java-split-string-commas)
 - [Compare Strings While Ignoring Whitespace in Java](https://www.baeldung.com/java-compare-string-whitespace)
+- [Concatenating Null Strings in Java](https://www.baeldung.com/java-concat-null-string)
 

Original file line number	Diff line number	Diff line change
`@@ -2,4 +2,5 @@`
`2`	`2`
`3`	`3`	`- [Ignoring Commas in Quotes When Splitting a Comma-separated String](https://www.baeldung.com/java-split-string-commas)`
`4`	`4`	`- [Compare Strings While Ignoring Whitespace in Java](https://www.baeldung.com/java-compare-string-whitespace)`
	`5`	`+- [Concatenating Null Strings in Java](https://www.baeldung.com/java-concat-null-string)`
`5`	`6`