Question

Instruction

This task is about using the Java Collections Framework to accomplish some basic textprocessing tasks. These questions involve choosing the right abstraction (Collection, Set, List, Queue, Deque, SortedSet, Map, or SortedMap) to efficiently accomplish the task at hand. The best way to do these is to read the question and then think about what type of Collection is best to use to solve it. There are only a few lines of code you need to write to solve each of them. Unless specified otherwise, sorted order refers to the natural sorted order on Strings, as defined by String.compareTo(s). Part 0 in the assignment is an example specification and solution.

Part0

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.HashSet;
import java.util.Iterator;
import java.util.Set;

public class Part0 {
  
   /**
   * Read lines one at a time from r. After reading all lines, output
   * all lines to w, outputting duplicate lines only once. Note: the order
   * of the output is unspecified and may have nothing to do with the order
   * that lines appear in r.
   * @param r the reader to read from
   * @param w the writer to write to
   * @throws IOException
   */
   public static void doIt(BufferedReader r, PrintWriter w) throws IOException {
Set<String> s = new HashSet<>();

for (String line = r.readLine(); line != null; line = r.readLine()) {
s.add(line);
}

for (String text : s) {
w.println(text);
}
   }

   /**
   * 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;
           if (args.length == 0) {
               r = new BufferedReader(new InputStreamReader(System.in));
               w = new PrintWriter(System.out);
           } else if (args.length == 1) {
               r = new BufferedReader(new FileReader(args[0]));
               w = new PrintWriter(System.out);              
           } else {
               r = new BufferedReader(new FileReader(args[0]));
               w = new PrintWriter(new FileWriter(args[1]));
           }
           long start = System.nanoTime();
           doIt(r, w);
           w.flush();
           long stop = System.nanoTime();
           System.out.println("Execution time: " + 10e-9 * (stop-start));
       } catch (IOException e) {
           System.err.println(e);
           System.exit(-1);
       }
   }
}

Question 6

[5 marks] Read the input one line at a time and output the current line if and only if it is not a suffix of some previous line. For example, if the some line is "0xdeadbeef" and some subsequent line is "beef", then the subsequent line should not be output.

Template code

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;

public class Part6 {
  
   /**
   * Your code goes here - see Part0 for an example
   * @param r the reader to read from
   * @param w the writer to write to
   * @throws IOException
   */
   public static void doIt(BufferedReader r, PrintWriter w) throws IOException {
       // 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;
           if (args.length == 0) {
               r = new BufferedReader(new InputStreamReader(System.in));
               w = new PrintWriter(System.out);
           } else if (args.length == 1) {
               r = new BufferedReader(new FileReader(args[0]));
               w = new PrintWriter(System.out);              
           } else {
               r = new BufferedReader(new FileReader(args[0]));
               w = new PrintWriter(new FileWriter(args[1]));
           }
           long start = System.nanoTime();
           doIt(r, w);
           w.flush();
           long stop = System.nanoTime();
           System.out.println("Execution time: " + 10e-9 * (stop-start));
       } catch (IOException e) {
           System.err.println(e);
           System.exit(-1);
       }
   }
}

Answer 1

Here is the complete code . Save it in file Part6.java

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.SortedSet;
import java.util.TreeSet;

public class Part6 {
/**
* Your code goes here - see Part0 for an example
* @param r the reader to read from
* @param w the writer to write to
* @throws IOException
*/

public static void doIt(BufferedReader r, PrintWriter w) throws IOException {
SortedSet < String > wordset = new TreeSet < String > ();
for (String line = r.readLine(); line != null; line = r.readLine()) {
boolean suffix = false;
//check if the line is a suffix of any of previous lines
for (String s: wordset)
{
if (s.endsWith(line)) //check if the string s ends with line
{
suffix = true;
break;
} else if (s.compareTo(line) > 0) //already reached a line that is greater than the search
break;
}
if (!suffix) // if line is not suffix of any previous , then add to set
wordset.add(line);
}
for (String text: wordset) {
w.println(text);
}
}
/**
* 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;
if (args.length == 0) {
r = new BufferedReader(new InputStreamReader(System.in));
w = new PrintWriter(System.out);
} else if (args.length == 1) {
r = new BufferedReader(new FileReader(args[0]));
w = new PrintWriter(System.out);
} else {
r = new BufferedReader(new FileReader(args[0]));
w = new PrintWriter(new FileWriter(args[1]));
}
long start = System.nanoTime();
doIt(r, w);
w.flush();
long stop = System.nanoTime();
System.out.println("Execution time: " + 10e-9 * (stop - start));
} catch (IOException e) {
System.err.println(e);
System.exit(-1);
}
}
}

Also create an input file inword.txt which contains following lines

child
start
tart
kill
children
motherhood
mother
0xdeadbeef
hood
complain
killing
beef

Compile the file and from command prompt run the code as

$ java Part6 inword.txt outword.txt

The output file outword.txt generated as below

0xdeadbeef
child
children
complain
hood
kill
killing
mother
motherhood
start

and output shows the execution time value as
Execution time: 0.03147977

From the contenet of outword file, we can see that the word beef and tart are missing as they are the suffix word of some words appeared before them  in inword.txt file .

Hence the purpose of the program is served.