Question

Java Programming: Can I get an example of a program that will allow 4 options?

Example Output:

Choose on of the options below:

1. Display all items in CSV file. (CSV file includes for example brand of phone, size, price)

2. Pick an item by linear searching

3. Pick an item by bineary searching

4. Quit Program

Answer 1

Phone.java

public class Phone {
private String brand;
private double size;
private double price;
  
public Phone()
{
this.brand = "";
this.size = 0.0;
this.price = 0.0;
}

public Phone(String brand, double size, double price)
{
this.brand = brand;
this.size = size;
this.price = price;
}

public String getBrand() {
return brand;
}

public void setBrand(String brand) {
this.brand = brand;
}

public double getSize() {
return size;
}

public void setSize(double size) {
this.size = size;
}

public double getPrice() {
return price;
}

public void setPrice(double price) {
this.price = price;
}
  
@Override
public String toString()
{
return("Brand: " + this.brand +
", Size: " + String.format("%.1f", this.size) +
", Price: $" + String.format("%.2f", this.price));
}
}

PhoneListMain.java (Driver class)

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Scanner;

public class PhoneListMain {
  
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
  
System.out.print("Enter the filename: ");
String fileName = sc.nextLine().trim();
  
// read from file and put the data into a list of Phones
ArrayList<Phone> phones = readData(fileName);
  
int choice;
  
do
{
displayMenu();
choice = Integer.parseInt(sc.nextLine().trim());
  
switch(choice)
{
case 1:
{
System.out.println("***** ALL ITEMS IN THE CSV FILE *****\n"
+ "-------------------------------------");
displayAllItems(phones);
break;
}
  
case 2:
{
System.out.print("\nEnter a phone brand to search: ");
String brand = sc.nextLine().trim();
linearSearch(phones, brand);
break;
}
  
case 3:
{
System.out.print("\nEnter a phone brand to search: ");
String brand = sc.nextLine().trim();
binarySearch(phones, brand);
break;
}
  
case 4:
{
System.out.println("\nGood Bye!\n");
System.exit(0);
}
  
default:
System.out.println("\nInvalid selection!\n");
}
}while(choice != 4);
}
  
private static void displayMenu()
{
System.out.print("Choose one of the options from below:\n"
+ "1. Display all items in CSV file\n"
+ "2. Pick an item by linear search\n"
+ "3. Pick an item by binary search\n"
+ "4. Quit\n"
+ "Enter your choice: ");
}
  
private static ArrayList<Phone> readData(String fileName)
{
ArrayList<Phone> phones = new ArrayList<>();
Scanner fileReader;
int count = 0;
  
try
{
fileReader = new Scanner(new File(fileName));
while(fileReader.hasNextLine())
{
String line = fileReader.nextLine().trim();
String[] data = line.split(",");
String brand = data[0];
double size = Double.parseDouble(data[1]);
double price = Double.parseDouble(data[2]);
  
phones.add(new Phone(brand, size, price));
  
// track number of lines read from file
count++;
}
fileReader.close();
}catch(FileNotFoundException fnfe){
System.out.println("Couldn't find file: " + fileName + "!\n");
System.exit(0);
}
  
System.out.println("Successfully read " + count + " phone data from file.\n");
  
return phones;
}
  
private static void displayAllItems(ArrayList<Phone> phones)
{
for(Phone phone : phones)
{
System.out.println(phone.toString());
}
System.out.println();
}
  
private static void linearSearch(ArrayList<Phone> phones, String brand)
{
int index = -1;
for(int i = 0; i < phones.size(); i++)
{
if(phones.get(i).getBrand().equals(brand))
{
index = i;
break;
}
}
  
if(index == -1)
System.out.println("\nSorry, no phones found for brand: " + brand + ".\n");
else
System.out.println("\nMatch found:\n" + phones.get(index).toString() + "\n");
}
  
private static void binarySearch(ArrayList<Phone> phones, String brand)
{
// variable to store the index of the found element
int index = -1;
  
// sort the list and then implement binary search
// here, bubble sorting method is used, any sorting technique can be used
  
// Copy the original list to another list so that the original list remains unchanged
ArrayList<Phone> phonesDummy = phones;
int len = phonesDummy.size();
  
for(int i = 0; i < len - 1; i++)
{
for(int j = 0; j < len - i - 1; j++)
{
if(phonesDummy.get(j).getBrand().compareToIgnoreCase(phonesDummy.get(j + 1).getBrand()) > 0)
{
// swap the elements
Phone temp = phonesDummy.get(j);
phonesDummy.set(j, phonesDummy.get(j + 1));
phonesDummy.set(j + 1, temp);
}
}
}
  
// now implement the binary search
int leftHalf = 0, rightHalf = len - 1;
while(leftHalf <= rightHalf)
{
int mid = leftHalf + (rightHalf - leftHalf) / 2;
int res = brand.compareTo(phonesDummy.get(mid).getBrand());
  
// element found at the mid index
if(res == 0)
index = mid;
  
// if brand name is greater, it must be present at the right half
// so, the left half is ignored
if(res > 0)
leftHalf = mid + 1;
  
// if brand name is smaller, it must be present at the left half
// so, the right half is ignored
else
rightHalf = mid - 1;
}
  
if(index == -1)
System.out.println("\nSorry, no phones found for brand: " + brand + ".\n");
else
System.out.println("\nMatch found:\n" + phones.get(index).toString() + "\n");
}
}

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