Question

I was trying case insensitive pattern matching. For the sake of learning i tried the following and finding it difficult to analyze what is happening.

   String x = "Hello";
   String pattern = "(?i)";
   System.out.println(x.replaceAll(pattern, "</code>")); 

Output is

</code>H</code>e</code>l</code>l</code>o</code>

Can someone please explain this behaviour

Answer 1

Using (?i) bare is equivalent to matching case-insensitive empty String

You need to have something after (?i) to apply case-insensitivity matching to..

That is why this pattern matches every empty string, after each character, and also before the first character, and replaces it with : – </code>