question: public StyledString insert ( char ch , int offset ) throws StringIndexOutOfBoundsException { if ( offset < 0 || offset > builder . length ( ) ) { throw new StringIndexOutOfBoundsException ( "Invalid offset (" + offset + ")" ) ; } builder . insert ( offset , ch ) ; return this ; }
target:  Inserts the character at the given offset. The inserted character will get the styler that is already at the given offset.