simple Data Structure in Java

can anyone help with this question?

[5 marks] Read the input one line at a time and output the current line if and only if you have already read at least 1000 lines greater than the current line and at least 1000 lines less than the current line. (Again, greater than and less than are with respect to the ordering defined by String.compareTo).) public static void dolt (BufferedReader r, Printwriter w) throws IOException /Your code goes here - see Parte for an example