Replacing in IntelliJ with regex - Reference: http://stackoverflow.com/questions/20742076/regex-replace-uppercase-with-lowercase-letters

IntelliJ.regex

Find: ^(\W+public void .*?)_([A-Z]{1})([a-zA-Z]*)_([A-Z]{1})([a-zA-Z]*)\(\) \{$
Replace: $1_\l$2$3_\l$4$5() {

This will cause all texts like this:
"    public void method1_DoThisDoThat_ReturnThisReturnThat() {"
be relaced with:
"    public void method1_doThisDoThat_returnThisReturnThat() {"