Part3.java

package comp2402a2; import java.io.BufferedReader; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.util.List; import java.util.ArrayList; public class Part3 { /** * Your code goes here - see Part0 for an example * @param x the number of lines to read in * @param r the reader to read from * @param w the writer to write to * @throws IOException */ public static void doIt(int x, BufferedReader r, PrintWriter w) throws IOException { // TODO: Your code goes here - see Part0 for an example } /** * The driver. Open a BufferedReader and a PrintWriter, either from System.in * and System.out or from filenames specified on the command line, then call doIt. * @param args */ public static void main(String[] args) { try { BufferedReader r; PrintWriter w; int x; if (args.length == 0) { x = 3; r = new BufferedReader(new InputStreamReader(System.in)); w = new PrintWriter(System.out); } else if( args.length == 1) { x = Integer.parseInt(args[0]); r = new BufferedReader(new InputStreamReader(System.in)); w = new PrintWriter(System.out); } else if (args.length == 2) { x = Integer.parseInt(args[0]); r = new BufferedReader(new FileReader(args[1])); w = new PrintWriter(System.out); } else { x = Integer.parseInt(args[0]); r = new BufferedReader(new FileReader(args[1])); w = new PrintWriter(new FileWriter(args[2])); } long start = System.nanoTime(); doIt(x, r, w); w.flush(); long stop = System.nanoTime(); System.out.println("Execution time: " + 1e-9 * (stop-start)); } catch (IOException e) { System.err.println(e); System.exit(-1); } } } 

Part0.java Example

package comp2402a2; import java.io.BufferedReader; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.util.List; import java.util.ArrayList; import java.util.Iterator; public class Part0 { /** * Read x lines one at a time from r. After reading x lines, output * the lines to w. * @param x the number of lines to read in * @param r the reader to read from * @param w the writer to write to * @throws IOException */ public static void doIt(int x, BufferedReader r, PrintWriter w) throws IOException { List l = new ArrayList(); // This is just a template, if that is helpful for you // This just reads in the first x lines from r // then prints those lines out in the order they were read. for (int i=0; i  
 
  3. [10 marks] Read the input one line at a time, and output the last x lines in reverse order, where x>=0 is a parameter to the do It method. If there are fewer than x lines, print the n=0 is a parameter to the do It method. If there are fewer than x lines, print the n