PROJECT Java File Processing Application: Java Data Analytics

Objective To type a simple Java program, execute ( run ) the program for some particular values, observe the output and then modify the program.

PROJECT DESCRIPTION

Design an application that uses sequential file processing to analyze a list of data values.

The initial starter code for your program is given in Figure 1 .

First run and test the starter code, which primarily has file processing objects that declare a file and write data to the file.

After you test the original starter code and verify its functionality, you will then modify the program according to the instructions that follow.

Your completed program ( after modification ) will perform, at the minimum, each of the following tasks

read from a text file and write to a text file

include a method that displays the data array, when requested

include a method to sort the data in the text file

locate the maximum and minimum values in the array

compute the average value of the data values

Basically, your program is outlined in the given starter code statements shown within Figure 1 , which follows. Review the starter code to understand the mechanisms of the interactions between reading a file and writing to a file. Perform any modifications according to this projects instructions.

Type, compile and run the basic Java program that is shown in Figure 1 , which follows. Then modify the program accordingly.

Information About This Project

The types of file processing include:

sequential access file processing data is accessed one line at a time

random access file processing data can be assessed in any order

Steps to Complete This Project

STEP 1 Open NetBeans or Eclipse

Open NetBeans or Eclipse and create a Java project with the following details.

For Project Name include: DataAnalytics

For the Main Class include: DataAnalytics

In your Code window for this class, shown below, copy the program code shown in Figure 1 below, in the appropriate places, except substitute your own name in place of Sammy Student.

STEP 2 Review the Starter Code for this Project

Before you run the initial starter code for this project, which is given in Figure 1 review the program statements that comprise the code. Basically, the starter code assigns a file name to a file writing object. A looping structure is then used to take values from the user and assign them to an array list. The data is also recorded to the declared text file.

PROJECT Java File Processing Application: Java Data Analytics

Figure 1 Source Code for the Data Analytics File Processing Program

import java.io.*;

import java.util.ArrayList;

import java.util.Scanner;

// Sammy Student: Data Analysis with Java File Processing

class DataAnalytics

{

public static void main(String args[])

{

// declare an object to receive the data

Scanner scan = new Scanner(System.in);

// declare an array list to hold the data

ArrayList list;

list = new ArrayList();

int count = 0;

int num = 0;

int val = 0;

String line = "";

try

{

// create or append to the file

FileWriter fileOut = new FileWriter("outData.txt");

BufferedWriter fout = new BufferedWriter(fileOut);

System.out.println("how many data items?");

count = scan.nextInt();

for (int i = 1; i <= count; i++)

{

System.out.println("enter a data value");

val = scan.nextInt();

fout.write(val + " ");

}

System.out.println("thank you ... the data has been recorded!");

// close the output stream objects

fout.close();

fileOut.close();

scan.close();

}

catch(Exception e)

{

// catch an exception if any arises

System.err.println("Error: " + e.getMessage());

}

}

}

PROJECT Java File Processing Application: Java Data Analytics

STEP 3 Build, Compile and Run the Program

From the menu select [ Run ] and click [ Run Project ] to run your app.

STEP 4 Test the Program and Write the Data

Once you have successfully compiled your program enter a valid list of data values as shown below. Your initial program code will request a count of data values to be recorded and then write the data values to a text file.

[ Program Output ]

how many data items?

5

enter a data value

20

enter a data value

50

enter a data value

10

enter a data value

80

enter a data value

90

thank you . . . the data has been recorded!

STEP 5 Open the Data File and Review the Contents of the File

Within your software development environment, click [ File ] and then [ Open ] to review the contents of the data file that was created by running the program. Locate the outData.txt text file and open the file to view its contents.

STEP 6 Read the Data File

Once you have successfully compiled and tested your starter program and opened the text file with the data, you will now supplement your program with some program code that will read the data in the outData.txt text file and individually place the data values into a Java ArrayList .

Place the statements that are shown in Figure 2 before the closing curly brace

" } " of the try block.

PROJECT Java File Processing Application: Java Data Analytics

Figure 2 Additional Source Code for the Data Analytics File Processing Program

// read the data

FileReader fileIn = new FileReader("outData.txt");

BufferedReader fin = new BufferedReader(fileIn);

while ((line = fin.readLine()) != null)

{

num = Integer.parseInt(line);

list.add(num);

System.out.println(num);

}

System.out.println("thank you ... the data has been received!");

fin.close();

fileIn.close();

Save your program and run the program with the sample data that was given earlier. Observe the output of your program.

STEP 7 Supplement the Program Code Statements

Supplement again the program by including a method that displays the data that was recorded into the Java ArrayList .

Within your program, create a method named DisplayData() , which has this signature and definition. Place the method below the main() method and before the closing curly brace " } " of the class definition.

public static void DisplayData(ArrayList num)

{

for (int i = 0; i < num.size(); i++)

System.out.println(num.get(i).toString());

}

Then, before the closing curly brace " } " of the try block, place these two statements.

System.out.println("display unsorted data");

DisplayData(list);

Save your program and run the program with the sample data that was given earlier.

Now include a method that will sort the data that was placed into the ArrayList . Place the method below the DisplayData() method and before the closing curly brace " } " of the class definition.

Use the Bubble Sort routine that follows in Figure 3 .

In an appropriate place in the main() method include these lines of code to show that the data has been sorted.

System.out.println("display sorted data");

DisplayData(list);

PROJECT Java File Processing Application: Java Data Analytics

Figure 3 Source Code for the Data Analytics File Processing Program

public static void BubbleSort(ArrayList num)

{

int j = 0;

boolean flag = true; // set the flag to true to begin first pass

int temp = 0; // define the holding variable

while (flag)

{

flag = false; //set flag to false awaiting a possible swap

for (j = 0; j < num.size() - 1; j++)

{

if (num.get(j) > num.get(j + 1))

// for descending sort change to <

{

temp = num.get(j); //swap the elements

num.set(j, num.get(j + 1));

num.set(j + 1, temp);

flag = true; //shows a swap occurred

}

}

}

}

STEP 8 Modify the Program

After testing your program that it displays the original data in an unsorted order and a sorted order, modify again the program to include each of these variations:

Add a new method named MaxMin() that will find the smallest and largest value in the ArrayList after the data has been sorted.

Add a new method named Average() that will find the average value in the ArrayList after the data has been sorted.

Add a new method named PerfectSquares() that will find any values in the ArrayList that are perfect squares, such as 36 or 121 .

Save your program and perform a trial run of it. Test your program with data similar to that shown below.