Question

Preamble The file releasedates.txt contains a list of video games and their release dates. Each line of the file contains the release date, a tab character, and then the name. The list is currently totally unsorted. The object of today's lab is to write a series of methods that allow us to perform the following tasks: read contents from a file and store them in array, sort the contents of the array by name or by date, and store the sorted array results back into a new text file. The first few lines of releasedates.txt look as follows: 04/26/16 Sega 3D Classics Collection 07/14/16 Batman: Arkham Underworld 06/24/16 Tokyo Mirage Sessions #FE File 1/0 [10 marks] 1. [5] Write the method String[] input(String filename) that accepts a file name as a parameter. This method should read in the data from the file and store it into an array, then return this array. 2. [5] Write the method void output(String filename, String[] info) that accepts a String called filename as a parameter. This method should create a new file called filename and write the contents of the array info neatly into the new file. Note: Your methods should work for any size of file. The file that the Lab Assistant will use to test your programs will not be the same releasedates.txt, and your program should work properly regardless.

The file containing the JAVA files, pseudocode file and doc file that have written for this lab.

Answer 1

JAVA Program with comments:

import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.StringTokenizer;

public class main {
//method for reading input from file
public static String[] input(String filename){
try {
File file = new File(filename);
Scanner reader = new Scanner(file);
ArrayList<String> lines = new ArrayList<String>();
//tokenize each line in date and name and add to arraylist
while (reader.hasNextLine()) {
String line = reader.nextLine();
String[] tokens = line.split("\t");
lines.add(tokens[0]);
lines.add(tokens[1]);
}
String[] str = new String[lines.size()];
int i = 0;
//putting lines into array of strings
for(String line:lines){
str[i++] = line;
}
return str;
}catch (IOException e){ //if there is an error while reading file
System.out.println("File Read error occurred.");
}
return new String[1];
}
//method for writing infor to output file
public static void output(String filename, String[] info){
try {
FileWriter fr = new FileWriter(filename);
//writing strings from array to the file
for (int i = 0; i < info.length; i = i + 2) {
fr.write(info[i] + "\t" + info[i + 1] + "\n");
}
fr.close();
}catch (IOException e){ //if error occur during writing to file
System.out.println("File Write error occurred.");
}
}
//method for sorting string array by month
public static String[] sortByMonth(String[] info){
String[] str = info;
for(int i=0;i<info.length;i=i+2){
for(int j=0;j<info.length-i-2;j=j+2){
if(info[j].compareTo(info[j+2])>0){ //if next date is lexicographically smaller than current then swap
String temp1=info[j],temp2=info[j+1];
info[j] = info[j+2];
info[j+1] = info[j+3];
info[j+2] = temp1;
info[j+3] = temp2;
}
}
}
return info; //return the sorted array
}
//method for sorting by name
public static String[] sortByName(String[] info){
for(int i=1;i<info.length;i=i+2){ //if next name is lexicographically smaller than current then swap
for(int j=1;j<info.length-i-2;j=j+2){
if(info[j].compareTo(info[j+2])>0){
String temp1=info[j-1],temp2=info[j];
info[j-1] = info[j+1];
info[j] = info[j+2];
info[j+1] = temp1;
info[j+2] = temp2;
}
}
}
return info; //return the sorted array
}
//main method
public static void main(String[] args) {
String[] str = input("C:\\Users\\achar\\IdeaProjects\\filehandling\\src\\input.txt");
output("SortedByName.txt", sortByName(str));
output("SortedByDate.txt", sortByMonth(str));

}
}
output files after running the program:

1 main.java SortedByDate.txt x # SortedByName.txt x input.txt x 6 outfile.txt x Þ7/14/16 Batman: Arkham Underworld 04/26/16 Sega 3D Classics Collection 06/24/16 Tokyo Mirage Sessions 2 3 4