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Wednesday, 14 December 2016

Chapter 12 Exercise 24, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

12.24 (Create large dataset)
Create a data file with 1,000 lines. Each line in the file consists of a
faculty member’s first name, last name, rank, and salary. The faculty member’s
first name and last name for the ith line are FirstNamei and LastNamei. The rank
is randomly generated as assistant, associate, and full. The salary is randomly
generated as a number with two digits after the decimal point. The salary for an
assistant professor should be in the range from 50,000 to 80,000, for associate professor
from 60,000 to 110,000, and for full professor from 75,000 to 130,000. Save the file in Salary.txt.
Here are some sample data:

    FirstName1 LastName1 assistant 60055.95
    FirstName2 LastName2 associate 81112.45
    FirstName1000 LastName1000 full 92255.21

import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;

public class Exercise_24 {

    static final String[] ranks = {"assistant", "associate", "full"};

    public static void main(String[] args) throws Exception {

// VERSION 1:
//        ArrayList<String> members = new ArrayList<>();
//        String lineSeparator = System.getProperty("line.separator");
//
//        for (int i = 1; i <= 1000; i++) {
//            members.add(createString(i) + lineSeparator);
//        }
//
//        writeToFile(members);

// VERSION 2:
        try (PrintWriter out = new PrintWriter("Salary.txt")) {
            for (int i = 1; i <= 1000; i++) {
                String rank = getRandomRank();
                String salary = String.format("%.2f", getRandomSalaryByRank(rank));

                out.print("FirstName" + i + " LastName" + i + " ");
                out.print(" " + rank + " " + salary);
                if (i != 1000) {
                    out.println();
                }

            }
        }

       System.out.println("File saved...");

    }

    private static void writeToFile(ArrayList<String> members) {

        try (PrintWriter out = new PrintWriter("Salary.txt")) {

            for (String member : members) {
                out.write(member);
            }
        } catch (FileNotFoundException ex) {
            ex.printStackTrace();;
        }
    }

    private static String createString(int i) {

        String rank = getRandomRank();
        double salary = getRandomSalaryByRank(rank);

        return "FirstName" + i + " LastName" + i + " " + rank + " " + String.format("%.2f", salary);
    }

    private static String getRandomRank() {
        return ranks[(int)(Math.random() * ranks.length)];
    }

    private static double getRandomSalaryByRank(String rank) {

        int max = 0;
        int min = 0;
        switch (rank) {
            case "assistant":
                min = 50000;
                max = 80000;
                break;
            case "associate":
                min = 60000;
                max = 110000;
                break;
            case "full":
                min = 75000;
                max = 130000;
                break;
        }
        return getRandomSalary(min, max + 1); //
    }

    /** returns a random double from min to max - 1 **/
    private static double getRandomSalary(int min, int max) {
        int range = max - min;

        return Math.random() * range + min;
    }
}

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