Run the following code to check how String class Methods work.

String myString $=$ "KOI is my University";

String s$1=$ "KOI";

String s$2=$ "koi";

String s$3="$ Hello KOI $"$;

System.out.println$("$Char at index $2($third char$)$: $"+$ myString.charAt$(2))$;

System.out.println$("$After Concat: $"+$ myString.concat$("-$Enjoy$-"))$;

System.out.println$("$Checking equals with case: $"+$s$2.$equals$($s$1))$;

System.out.println$("$Checking Length: $"+$ myString.length$())$;

System.out.println$("$Replace function: $"+$ myString.replace$("$fun$",$ "easy"$))$;

System.out.println$("$SubString of myString: $"+$ myString.substring$(8))$;

System.out.println$("$SubString of myString: $"+$ myString.substring$(8,12))$;

System.out.println$("$Converting to lower case: $"+$ myString.toLowerCase$())$;

System.out.println$("$Converting to upper case: $"+$ myString.toUpperCase$())$;

System.out.println$("$Triming string: $"+$ s$3.$trim$())$;

System.out.println$("$searching s$1$ in myString: $"+$ myString.contains$($s$1))$;

System.out.println$("$searching s$2$ in myString: $"+$ myString.contains$($s$2))$;