i have a school assignment which requires me to add an unknown number of instances of a class "fruit" in to an arraylist "basket" and print out the details of each fruit object, my code adds the fruits to the arraylist but seems to override the previous entry each time leaving me with an arraylist of the same project. This is my code so far:
import java.util.*;
public class Question1
{
public static void main(String[]Augs)
{
List<Fruit> basket = new ArrayList<Fruit>();
int input;
Scanner inp = new Scanner(System.in);
String name;
String colour;
double mass;
int k = -1;
while (true)
{
System.out.println("Enter option: (1) add fruit (2) quit:");
input = inp.nextInt();
if (input==2)
break;
else
{
k++;
System.out.println("Enter name, colour and mass in kg separated by space");
name = inp.next();
colour = inp.next();
mass = inp.nextDouble();
Fruit temp = new Fruit(name, colour, mass);
basket.add(temp);
}
}
for (int i = 0; i<basket.size(); i++)
{
System.out.println(basket.get(i));
}
}
}
//fruit class
public class Fruit
{
private String name;
private String colour;
private double mass;
public Fruit(String name, String colour, double mass)
{
this.name=name;
this.colour=colour;
this.mass=mass;
}
public String toString()
{
return name + " " + colour + " " + mass;
}
}
Your code looks just fine in terms of adding the fruits to the basket. I think what's getting you is System.out.println(basket.get(i)). You are essentially asking a Fruit object to be printed, but the run time does not know how to do that and as such tries to convert the Fruit to some String representation by calling the toString() method on it. I think your Fruit class prints the same String no matter what's inside it. Try overriding the toString() method to get the correct results.
public class Fruit
{
#Override
public String toString()
{
return this.getName() + " " + this.getColor() + " " + this.getMass();
}
}
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So everything works great in my program, but I read that making variable not private in class is a big mistake, because it can make problems with others part of big program.
Well I tried making HashMap airplane and flight private but I get error that "The field Airplane.airplane is not visible",which is of course true.
But how do I then make it visible in interface class?
Thanks in advance, I'm still learning and I got to this part in course.
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner imeskanera = new Scanner(System.in);
Airplane airplane = new Airplane();
flight flight = new flight();
interface_aerodrom ui = new interface_aerodrom(imeskanera,airplane,flight);
ui.start();
}
}
/ Airplane class
import java.util.HashMap;
public class Airplane {
HashMap<String,Integer>airplane;
private String id;
private int capacity;
public Airplane() {
this.airplane = new HashMap<String,Integer>();
}
public void add(String id, int capacity) {
this.id = id;
this.capacity = capacity;
this.airplane.put(id, capacity);
}
public String id() {
return this.id;
}
public int capacity() {
return this.capacity;
}
public String airplaneinfo() {
return this.id + "( " + this.capacity + " )";
}
}
/interface class
import java.util.Scanner;
public class interface_aerodrom {
private Scanner imeskanera;
private Airplane airplane;
private flight flight;
public interface_aerodrom(Scanner scanner, Airplane airplane,flight flight) {
this.imeskanera = scanner;
this.airplane = airplane;
this.flight = flight;
}
public void start() {
System.out.println("Airport panel\r\n"
+ "--------------------");
System.out.println();
while(true) {
System.out.println("Choose operation:\r\n"
+ "[1] Add airplane\r\n"
+ "[2] Add flight\r\n"
+ "[x] Exit");
String input = this.imeskanera.nextLine();
input = input.toLowerCase();
input = input.trim();
if(input.equals("x")) {
flight_service();
break;
}
else if(input.equals("1")) {
addairplane();
}
else if(input.equals("2")){
addflight();
}
}
}
public void flight_service() {
System.out.println("Flight service\r\n"
+ "------------");
while(true) {
System.out.println("Choose operation:\r\n"
+ "[1] Print planes\r\n"
+ "[2] Print flights\r\n"
+ "[3] Print plane info\r\n"
+ "[x] Quit");
String input = this.imeskanera.nextLine();
input = input.toLowerCase();
input = input.trim();
if(input.equals("quit")){
break;
}
else if(input.equals("1")) {
for(String name : this.airplane.airplane.keySet()) {
int numberofseats = this.airplane.airplane.get(name);
String list = name + "( " + numberofseats + " )";
System.out.println(list);
}
}
else if(input.equals("2")){
for(String name : this.flight.flight.keySet()) {
String value = this.flight.flight.get(name);
String list = name + value;
System.out.println(list);
}
}
else if(input.equals("3")) {
System.out.println("Give plane ID: ");
String planeid = this.imeskanera.nextLine();
if(airplanecontains(planeid)) {
int numberofseats = this.airplane.airplane.get(planeid);
System.out.println(planeid + "( " + numberofseats + " )" );
} else {
System.out.println("That plane is not in our database");
}
}
}
}
public void addairplane() {
System.out.println("Give plane ID: ");
String ID = this.imeskanera.nextLine();
System.out.println("Give plane capacity: ");
int capacity = Integer.parseInt(this.imeskanera.nextLine());
this.airplane.add(ID, capacity);
}
public boolean airplanecontains(String ID) {
if(this.airplane.airplane.containsKey(ID)) {
return true;
}else {
return false;
}
}
public void addflight() {
System.out.println("Give plane ID: ");
String ID = this.imeskanera.nextLine();
if(airplanecontains(ID)) {
System.out.println("Give departure airport code: ");
String departure = this.imeskanera.nextLine();
System.out.println("Give destination airport code: ");
String destination = this.imeskanera.nextLine();
int seats = this.airplane.airplane.get(ID);
this.flight.flight.put(ID + " ( " + seats + " ) ",departure + "-" + destination);
}
else {
System.out.println("This plane is not in our database");
}
}
}
/ flight class
import java.util.HashMap;
public class flight {
HashMap<String,String>flight;
public flight() {
this.flight = new HashMap<String,String>();
}
public void add(String departure, String destination) {
this.flight.put(departure, destination);
}
}
Making a field private does not necessarily mean you can't share it. You can use a getter to return the HashMap.
private Map<String,Integer>airplane = new HashMap<>();
public Map<String,Integer> getAirPlaneMap() {
return airplane;
}
The reason being is that this hides implementation details and allows for future changes without affecting users of the class. Users don't need to know where the map comes from within your class. You could have retrieved it from some where yourself and the user wouldn't know.
You may also want to ensure a user can't change it. So you could do the following:
public Map<String,Integer> getAirPlaneMap() {
return Collections.unModifiableMap(airplane);
}
The above will prevent the user from adding or deleting map elements. But it won't prevent them from changing a retrieved object from the map unless that object is also immutable.
In general, setter and getters are the best way to allow users to set and retrieve values. And it is usually a good idea to make defensive copies of mutable items that they are retrieving to ensure that the retrieved values are consistent for all users during execution of the program.
This question already has answers here:
What's the simplest way to print a Java array?
(37 answers)
Closed 3 years ago.
New here, so please go easy on me! I've searched other articles on the subject but can't quite find the answer i'm looking for. Hoping someone can help.
Two separate classes, object class and main method. I need to print the object details using toString, but I can't work out how to print the toppings, which are being passed as an array from the main method. The code runs ok, but when I call getToppings() from the toString method, it just prints the id of the array object name, rather than the contents of the array itself.
Can anyone help?
Thanks in advance,
Marc
package toString;
/*
* class to represent a pizza object.
*/
public class Pizza
{
private String name;
private String [] toppings;
private double price;
public Pizza(String reqName, String [] reqToppings, double reqPrice)
{
name = reqName;
toppings = reqToppings;
price = reqPrice;
}
public String getName()
{
return name;
}
public String[] getToppings()
{
return toppings;
}
public double getPrice()
{
return price;
}
public String toString()
{
return "The pizza name is " + getName() + ", the toppings are " + getToppings() + " and the price is £" + getPrice();
}
}
package toString;
public class TestPizza
{
public static void main(String[] args)
{
String[] pepperoni = {"Pepperoni", "minced beef"};
String[] diavalo = {"Pepperoni", "minced beef", "chillies"};
String[] chicken = {"Chicken", "sweetcorn"};
Pizza [] pizzaList = new Pizza[3];
pizzaList[0] = new Pizza("Pepperoni", pepperoni, 6.95);
pizzaList[1] = new Pizza("Diavalo", diavalo, 7.95);
pizzaList[2] = new Pizza("Chicken & Sweetcorn", chicken, 8.95);
System.out.println(pizzaList[0].toString());
System.out.println(pizzaList[1].toString());
System.out.println(pizzaList[2].toString());
}
}
You have to go through array and print out every item:
public String toString(){
String s = "The pizza name is " + getName() + ", the toppings are: ";
for(int i = 0; i<getToppings().size; i++){
s += getToppings[i] + ", ";
}
s += "and the price is £" + getPrice();
return s;
}
I have another small class containing the main method that display the
invoice, but the toString method here is only displaying the last item
entered, not the three itemnames,quantities, prices and totalPrice.
I have doubts about addItemLine and toString.
Can someone see what I am missing here?
I was enable to past the lineItem class code.
import java.util.ArrayList;
import java.util.Scanner;
public class Transaction {
private ArrayList<lineItem> lineItems;
private int customerID;
private String customerName;
public Transaction (int customerID, String customerName){
this.customerID= customerID;
this.customerName= customerName;
this.lineItems= new ArrayList<>();
}
public int getcustomerID(){
return customerID;
}
public void setcustomerID(int customerID){
this.customerID = customerID;
}
public String getcustomerName(){
return customerName;
}
public void setcustomerName(String customerName){
this.customerName = customerName;
}
public ArrayList addItemLine(lineItem line){
Scanner mykey=new Scanner(System.in);
for (int i=0; i<2;i++){
String k= line.getItemName();
int m= line.getQuantity();
double d= line.getPrice();
System.out.println("enter item name:");
k = mykey.next();
line.setItemName(k);
System.out.println("enter quantity:");
m= mykey.nextInt();
line.setQuantity(m);
System.out.println("enter unit price:");
d= mykey.nextDouble();
line.setPrice(d);
line.getItemName(); line.getQuantity(); line.getPrice();
lineItems.add(new lineItem(k,m,d));
}
return this.lineItems;
}
public void updateItem(String item, int quant, double pri){
lineItem l= new lineItem(item, quant, pri);
int m=0;
m= l.getQuantity();
m=m+quant;
double tot=0;
}
public double getTotalPrice(){
double totalPrice = 0;
for (int i =0;i<2; i++){
lineItem item = lineItems.get(i);
totalPrice = totalPrice + item.getTotalPrice();
}
return totalPrice;
}
public String getLineItem( String s, int d, double k){
lineItem o= new lineItem(s,d,k);
for (int i =0;i<2; i++){
if (!s.equals(o.getItemName()))
System.out.println("item not found");
else
s= (o.getItemName() + o.getQuantity() + o.getPrice());
}
return s;
}
public String toString(lineItem lin) {
String a="", b="";
a=("Customer ID:" + this.getcustomerID() + "\n" + "Customer Name: " +
this.getcustomerName());
for (int i=0; i<2;i++){
b= ("\n\n" + lin.getItemName() + "\t" + "Qty" + lin.getQuantity() + "
"
+ "#" + lin.getPrice() + " "+ "\t" + "$" + lin.getTotalPrice());
}
return a + b;
}
TransactionTesting:
import java.util.Scanner;
public class TransactionTesting {
public static void main(String args[]) {
String m=""; int g=0; double r=0; int id=0; String name="";
Scanner mykey= new Scanner(System.in);
System.out.println("enter customer name:");
name= mykey.nextLine();
System.out.println("enter customer ID:");
id=mykey.nextInt();
Transaction mytrans= new Transaction(id, name);
lineItem line= new lineItem(m,g,r);
mytrans.addItemLine(line);
System.out.println(mytrans.toString(line));
}
}
Change your toString() method like this:
public String toString() {
String a="", b="";
a=("Customer ID:" + this.getcustomerID() + "\n" + "Customer Name: " +
this.getcustomerName());
for (lineItem item : this.lineItems)
b += ("\n\n" + item.getItemName() + "\t" + "Qty" + item.getQuantity() + " "
+ "#" + item.getPrice() + " "+ "\t" + "$" + item.getPrice());
return a + b;
}
and from your test class call this method as the following:
System.out.println(mytrans.toString());
You don't need any argument in order to print your entire list.
Try to refactor your code a bit. It works, but it can be written better and better ;)
1) The call
System.out.println(mytrans.toString(line));
is printing out the single lineitem that is passed to it. What you probably intended was for Transaction.toString() to iterate over its list Transaction.lineItems and print each item in turn.
In fact Transaction.toString() doesn't need to take in a lineItem argument, the method should merely print out the internals of the class instance.
2) There is a similar confusion in Transacton.addItemLine(). It accepts a lineItem, prompts the user for new values, updates lineItem.. then constructs a new lineItem to store in Transaction.lineItems. It isn't actually causing a bug that I can see but you should get rid of the lineItem argument entirely; addItemLine doesn't need it.
3) Incidentally:
for (int i=0; i<2;i++){ }
loops twice, not three times. I trust you would have caught that in testing.
4) There is also a line of code near the end of addItemLine that doesn't actually do anything! Maybe you can spot that one on your own.
There are some other issues but those are the ones that leapt out at me.
Just a quick non-tested solution that may work. Something is copied from your code, something is changed because your code was wrong.
// If you create this inside the method than you'll lose everything everytime you call addItemLine
private ArrayList<lineItem> lineItems;
public void addItemLine(lineItem line){
Scanner mykey=new Scanner(System.in);
for (int i=0; i<2;i++){
String k= line.getItemName();
int m= line.getQuantity();
double d= line.getPrice();
System.out.println("enter item name:");
k = mykey.next();
line.setItemName(k);
System.out.println("enter quantity:");
m= mykey.nextInt();
line.setQuantity(m);
System.out.println("enter unit price:");
d= mykey.nextDouble();
line.setPrice(d);
line.getItemName(); line.getQuantity(); line.getPrice();
lineItems.add(new lineItem(k,m,d));
// This doesn't have to return anything, it just adds to the list
}
// No parameteres, this should build the string for the current object
public String toString() {
// String concatenation is not the best idea, StringBuilder is better
StringBuilder sb = new StringBuilder();
// If you want to print all of them then you need to iterate over the list
for (lineItem item : lineItems){
sb.append("Customer ID:" + this.getcustomerID() + "\n" + "Customer Name: " + this.getcustomerName());
for (int i=0; i<2;i++){
// Copied from your code
sb.append("\n\n" + lin.getItemName() + "\t" + "Qty" + lin.getQuantity() + " "+ "#" + lin.getPrice() + " "+ "\t" + "$" + lin.getTotalPrice());
}
sb.append("\n);
}
return sb.toString();
}
It seems that you don't understand how to create a Java object, or how to keep your application model separate from your application view.
Here's a test run of your code, after I made some changes.
Enter customer name: Gilbert
Enter customer ID: 123
Enter item name: Spinach
Enter quantity: 5
Enter unit price: .89
Customer ID: 123
Customer Name: Gilbert
Spinach Qty 5 #0.89 $4.45
Enter item name: Corn
Enter quantity: 12
Enter unit price: .29
Customer ID: 123
Customer Name: Gilbert
Corn Qty 12 #0.29 $3.4799999999999995
Enter item name:
First, let's look at your Java objects. The first Java object which you didn't include, is LineItem. Note that Java class names start with a capital letter.
package com.ggl.transaction;
public class LineItem {
private String itemName;
private int quantity;
private double price;
public LineItem(String itemName, int quantity, double price) {
this.itemName = itemName;
this.quantity = quantity;
this.price = price;
}
public String getItemName() {
return itemName;
}
public void setItemName(String itemName) {
this.itemName = itemName;
}
public int getQuantity() {
return quantity;
}
public void setQuantity(int quantity) {
this.quantity = quantity;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public double getTotalPrice() {
return price * quantity;
}
}
A Java object consists of class fields, and getters and setters for the fields.
Next, here's your Transaction class.
package com.ggl.transaction;
import java.util.ArrayList;
import java.util.List;
public class Transaction {
private List<LineItem> lineItems;
private int customerID;
private String customerName;
public Transaction(int customerID, String customerName) {
this.customerID = customerID;
this.customerName = customerName;
this.lineItems = new ArrayList<>();
}
public int getcustomerID() {
return customerID;
}
public void setcustomerID(int customerID) {
this.customerID = customerID;
}
public String getcustomerName() {
return customerName;
}
public void setcustomerName(String customerName) {
this.customerName = customerName;
}
public void addItemLine(LineItem line) {
this.lineItems.add(line);
}
public void updateItem(String item, int quant, double pri) {
LineItem l = new LineItem(item, quant, pri);
int m = 0;
m = l.getQuantity();
m = m + quant;
l.setQuantity(m);
}
public double getTotalPrice() {
double totalPrice = 0;
for (int i = 0; i < 2; i++) {
LineItem item = lineItems.get(i);
totalPrice = totalPrice + item.getTotalPrice();
}
return totalPrice;
}
public String getLineItem(String s, int d, double k) {
LineItem o = new LineItem(s, d, k);
for (int i = 0; i < 2; i++) {
if (!s.equals(o.getItemName()))
System.out.println("item not found");
else
s = (o.getItemName() + o.getQuantity() + o.getPrice());
}
return s;
}
public String toItemString(LineItem lin) {
String b = "";
String a = ("Customer ID: " + this.getcustomerID() + "\n"
+ "Customer Name: " + this.getcustomerName());
for (int i = 0; i < 2; i++) {
b = ("\n\n" + lin.getItemName() + "\t" + "Qty " + lin.getQuantity()
+ " " + "#" + lin.getPrice() + " " + "\t" + "$"
+ lin.getTotalPrice() + "\n");
}
return a + b;
}
}
I simplified your addItemLine class. Code that receives input using the Scanner class belongs in your TransactionTesting class.
I renamed your toString method to toItemString. toString is a method of the Object class. Since your method has a parameter, I renamed it to lessen any confusion.
Finally, here's your TransactionTesting class. I fixed it up so it would work. You can specify any number of line items. To stop processing, just enter a blank item name.
package com.ggl.transaction;
import java.util.Scanner;
public class TransactionTesting {
public static void main(String args[]) {
Scanner mykey = new Scanner(System.in);
System.out.print("Enter customer name: ");
String name = mykey.nextLine().trim();
System.out.print("Enter customer ID: ");
int id = Integer.valueOf(mykey.nextLine().trim());
Transaction mytrans = new Transaction(id, name);
boolean processing = true;
while (processing) {
System.out.print("Enter item name: ");
String k = mykey.nextLine().trim();
if (k.equals("")) {
processing = false;
} else {
System.out.print("Enter quantity: ");
int m = Integer.valueOf(mykey.nextLine().trim());
System.out.print("Enter unit price: ");
double d = Double.valueOf(mykey.nextLine().trim());
LineItem lineItem = new LineItem(k, m, d);
mytrans.addItemLine(lineItem);
System.out.println("\n" + mytrans.toItemString(lineItem));
}
}
mykey.close();
}
}
Remember, keep your application model (LineItem & Transaction) separate from your application view (TransactionTesting).
Simply put, in your method "addItemLine" you take data from 1 lineItem, overwrite it with some keyboard input, and the put in the list 2 other lineItem instances.
Then in the test code you print the original lineItem, which is not even in the list.
The method itself iterates on nothing, just creates twice the same string "b".
I suggest you to look at some tutorials on arrays and for loops.
All,
Below code is working fine with the ArrayList. could you please help me on how to get user input for name gender and amountSpent (array size [4]), then split it by spaces so that it will have String, String and double.
Also, How to display the result of only the customer who has higher amount Spent then the other Customers.
thank you in advance!
Regards,
Viku
import java.util.Comparator;
public class Customer implements Comparable <Customer>{
public String name,gender;
public double amountSpent;
public Customer(String name, String gender, double amountSpent) {
super();
this.name = name;
this.gender = gender;
this.amountSpent = amountSpent;
}
public String getCustomername() {
return name;
}
public void setCoustomername(String name) {
this.name = name;
}
public String getgender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public double getamountSpent() {
return amountSpent;
}
public void setamountSpent(double amountSpent) {
this.amountSpent = amountSpent;
}
public static Comparator <Customer> CustomerNameComparator = new Comparator<Customer>() {
public int compare(Customer c1, Customer c2) {
String custName1 = c1.getCustomername().toUpperCase();
String custName2 = c2.getCustomername().toUpperCase();
//ascending order
//return custName1.compareTo(custName2);
//descending order
return custName2.compareTo(custName1);
}
};
public static Comparator <Customer> CustomerAmountSpentComparator = new Comparator<Customer>() {
public int compare(Customer aS1, Customer aS2) {
int custamtspent1 = (int) aS1.getamountSpent();
int custamtSpent2 = (int) aS2.getamountSpent();
//ascending order sort
// return custamtspent1 - custamtSpent2;
//descending order sort
return custamtSpent2 - custamtspent1;
}
};
#Override
public int compareTo(Customer o) {
return 0;
}
#Override
public String toString() {
return " Customer Name : " + name + ", Gender : " + gender + ", Amount Spent : " + amountSpent + "";
}
}
and Main Program:
import java.util.ArrayList;
import java.util.Collections;
public class MainProg {
public static void main(String args[]){
String nL = System.lineSeparator();
try {
ArrayList<Customer> arraylist = new ArrayList<Customer> ();
arraylist.add(new Customer ("Louis","Male", 4567.76));
arraylist.add(new Customer ("Daniela","Female", 7653.67));
arraylist.add(new Customer ("Jenny","Female", 3476.98));
arraylist.add(new Customer ("Arijit","Male", 9876.44));
System.out.println("Customer Name Decending Sort: " + nL);
Collections.sort(arraylist, Customer.CustomerNameComparator);
for (Customer str: arraylist) {
System.out.println(str);
}
System.out.println(nL + "Custmer Amount Spent [Hight to Low] Sorting: " + nL);
Collections.sort(arraylist, Customer.CustomerAmountSpentComparator);
for (Customer str: arraylist){
System.out.println(str);
}
System.out.println(nL + "Highest Amount Spent Custmer Detail: " + nL);
}
catch (Exception e){
System.out.println("Error: " + e);
}
finally {
System.out.println(nL + "Report Completed!");
}
}
}
OPTION 1 (suggested):
If the user is to input the data, why do you need to split it up? Just do as follows:
System.out.println("Name:");
name = scn.nextLine();
System.out.println("Gender:");
gender = scn.nextLine():
System.out.println("Amt:");
amt = scn.nextDouble();
Customer c1 = new Customer (name,gender, amt);
OPTION 2:
Alternatively, if you want user to input everything in one single line (separated by spaces), just do this:
System.out.println("Input name, gender, amt:");
name = scn.next();
gender = scn.next():
amt = scn.next();
Customer c1 = new Customer (name,gender, amt);
PROGRAM OUTPUT: Input name, gender, amt: John Male 33.50
OPTION 3 (requested by you):
Lastly if you still insist of doing a split by space, and you want to accept the user input in one string separated by spaces:
System.out.println("Input name, gender, amt:");
input = scn.nextLine();
String[] token = input.split(" ");
String name = token[0];
String gender = token[1];
double amt = Double.parseDouble(token[2]);
Customer c1 = new Customer (name,gender, amt);
PROGRAM OUTPUT: Input name, gender, amt: John Male 33.50
For your first question (if I have understood right), you want to take a user input as string:
Dave Male 123.45
and then parse this into two Strings and a double. Scanner as you mentioned is a good way to start, then try
String[] parts = input.split(" ");
double value = Double.parseDouble(parts[2]);
This will split the input into a String array of size 3 and convert the third element to a double object, that will allow you to create Customers.
For your second question, you can use a simple approach by iterating over all Customers in the ArrayList, and store the current customer with the highest amount. Replacing the customer if you find a bigger spender.
Viku, try moving
arraylist.add(new Customer(name,gender,amountSpent));
to within the
do{
...
arraylist.add(new Customer(name,gender,amountSpent));
} while(choice.equalsIgnoreCase("Yes"));
As the code is now, the arrayList.add is only executed after the loop -> only last entry.
I am working on a program where I have to call a method that prompts the user to enter data from another class. This program should print the name, age, address, and gender of customers. However, I am having problem to call a method for inputting each customer information.
Also, I have to create a method that sort the ages of customers in ascending order. So the program prints out all info based on the order of age from the (youngest customer) to the (oldest one). I am not sure how to create a method that will only sort the ages of customers without sorting the name, address, and gender. I would really appreciate any feedback or comments!
This is what I have so far.
import java.util.Scanner;
public class Customer1 {
public static void main(String [] args){
Scanner input = new Scanner(System.in);
int x;
System.out.print("Total number of customers: ");
x = input.nextInt();
Customer [] person = new Customer[x];
System.out.println("Name" + " " + "Age"+ " " + "Address" + " " + "Gender");
for(int i = 0; i < person.length; i++){
System.out.println(person.toString());
}
}
}
class Customer{
String name;
int age;
String address;
String gender;
public Customer(String newName, int newAge, String newAddress, String newGender){
name = newName;
age = newAge;
address = newAddress;
gender = newGender;
}
public void data(Customer [] person){
Scanner input = new Scanner(System.in);
for(int i = 0; i < person.length; i++){
System.out.print("Name: ");
name= input.toString();
System.out.print("Age: ");
age = input.nextInt();
System.out.print("Address: ");
address= input.toString();
System.out.print("Gender: ");
gender = input.toString();
}
}
/*This is the "uncompleted" method that I tried to create in order to sort the ages of customers.
But I don't know how to use it in order to sort only the ages*/
public void sort(Customer [] person){
double temp;
for(int a = 0; a < (person.length - 1); a++){
for( int b = (a + 1); b < person.length; b++){
if(person[a] > person[b]){
temp = person[a];
person[a] = person[b];
person[b] = temp;
}
}
}
}
public String toString(){
String result;
result = name + " " + age + " " + address + " " + gender;
return result;
}
}
I recommend you to rethink a little bit your code and take a look at the following tips
Using Comparator or Comparable interfaces
These interfaces helps you out with the sorting of your collections, lists and etc, i.e, the Comparator interface allows you to impose ordering to your collection with a hand from Collections.sort and Arrays.sort operations.
You must define the implementation of you Comparator, based on you target class(Person), then define the ordering by any field you want:
class PersonSort implements Comparator<Person>{
#Override
public int compare(Person p1, Person p2) {
return p1.getAge() - p2.getAge();
}}
Then you are allowed to force its ordering via Arrays.sort(T[], Comparator):
Arrays.sort(yourArray, new PersonSort());
I also recommend you to take a look at Oracle's Collection Framework Tutorial. You will find information over ordering, implementations and etc.
Try out the below code which might solve this question .. I have included the methods suggested in the previous replies and created this program ..
import java.util.Scanner;
public class ReadSortCustomerData {
public static void main(String [] args) {
int numberOfCustomers;
Scanner input = new Scanner(System.in);
System.out.print("Enter the total number of customers: ");
numberOfCustomers = input.nextInt();
CustomerData [] customer = new CustomerData[numberOfCustomers];
for(int countCustomer=0 ; countCustomer < numberOfCustomers; countCustomer++) {
System.out.println("Enter the name of the"+(countCustomer+1)+"customer");
customer[countCustomer].setName(input.next());
System.out.println("Enter the age of the"+(countCustomer+1)+"customer");
customer[countCustomer].setAge(input.nextInt());
System.out.println("Enter the gender of the"+(countCustomer+1)+"customer");
customer[countCustomer].setGender(input.next());
System.out.println("Enter the address of the"+(countCustomer+1)+"customer");
customer[countCustomer].setGender(input.next());
}
}
public CustomerData[] sortCustomerData(CustomerData[] customers) {
for (int i=0;i<customers.length;i++) {
for(int j=i+1;j<customers.length;j++) {
if(ageCompare(customers[i], customers[j])==1) {
CustomerData tempCustomer = new CustomerData();
tempCustomer = customers[i];
customers[i] = customers[j];
customers[j] = tempCustomer;
}
}
}
return customers;
}
public int ageCompare(CustomerData a, CustomerData b)
{
return a.getAge() < b.getAge() ? -1 : a.getAge() == b.getAge() ? 0 : 1;
}
}
import java.util.Comparator;
import java.util.Scanner;
public class CustomerData {
private String name;
private int age;
private String address;
private String gender;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
}
This might need some tweaking during the run time but it should give you a good start.
1. Getting the data that you require
Currently in your Customer1 class you're accepting an x amount of customers provided from user input. Following which you create an array for x Customer objects. You do not currently populate the array with any data.
Customer[] person = new Customer[x];
After this line you could then do a for loop with the following:
String name;
int age;
String address;
String gender;
for( int i = 0; i < person.length; i++ )
{
System.out.print("Name: ");
name = input.next();
System.out.print("Age: ");
age = input.nextInt();
System.out.print("Address: ");
address= input.next();
System.out.print("Gender: ");
gender = input.next();
person[i] = new Customer( name, age, address, gender );
}
A cavaet must be observed in your code, you've put input.toString(). This will give you a string representation of your scanner, not the input. input.next() will give you next input as a string.
2.Sorting
I would advise looking at the comparator documentation. Have a comparator object that implements comparator with Customer as the type parameter. Override the compare to check against each Customer object's age.
Example would be:
class CustomerComparator implements Comparator<Customer>
{
#Override
public int compare(Customer a, Customer b)
{
return a.age < b.age ? -1 : a.age == b.age ? 0 : 1;
}
}
You should look into making the variables name, age, address gender private and using getX() methods (getters/setters).