Note for monitoring buy/sell item list
$begingroup$
I'm making note where you can add items that you buy or sell, any suggestions?
public class Main {
private static Scanner in = new Scanner(System.in);
private static String commands = "[-1]Quit, [0]Commands, [1]Available items, [2] Sold items, [3]Add, [4]Delete,"
+ " [5]Edit, [6]Sell. [7]Bilans [8]Details";
public static void main(String args) {
Storage storage = new Storage(5);
storage.addItem();
System.out.println("| RESELL NOTE |");
System.out.println(commands);
boolean flag = true;
while (flag) {
System.out.println("Choose option: (0 - print list)");
int answer = in.nextInt();
switch (answer) {
default:
System.out.println("Wrong command");
break;
case -1:
System.out.println("QUIT");
flag = false;
break;
case 0:
System.out.println(commands);
break;
case 1:
storage.availableItems();
break;
case 2:
storage.soldItems();
break;
case 3:
storage.addItem();
break;
case 4:
storage.removeItem();
break;
case 5:
System.out.println("modify item");
break;
case 6:
storage.sellItem();
break;
case 7:
storage.bilans();
break;
case 8:
storage.details();
}
}
}
}
public class Storage {
private int maxCapacity;
public Storage(int maxCapacity) {
this.maxCapacity = maxCapacity;
}
Scanner in = new Scanner(System.in);
private Map<Integer, Item> items = new TreeMap<>();
public void availableItems() {
System.out.println("Available items:");
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().sold) {
System.out.println(entry.getKey() + ". " + entry.getValue().getName());
}
}
}
public void soldItems() {
System.out.println("Sold items:");
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (entry.getValue().sold) {
System.out.println(entry.getKey() + "." + entry.getValue().getName()
+ " - (" + (entry.getValue().soldPrice - entry.getValue().price + "PLN profit)"));
}
}
}
public void addItem() {
if (items.size() >= maxCapacity) {
System.out.println("You cant add more items, storage full! (" + items.size() + "/" + maxCapacity + ")");
} else {
items.put(Item.assignId(), new Shoes("Piraty", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Belugi", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Zebry", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Creamy", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Sezame", 1500, 7, "red", 11));
System.out.println("Item added");
}
}
public void modifyItem() { // work in progress
printInLine();
System.out.println("nPick item to modify: ");
int id = in.nextInt();
if (items.containsKey(id)) {
System.out.println("Enter new name for " + items.get(id).getName());
in.nextLine();
String newName = in.nextLine();
items.get(id).setName(newName);
} else {
System.out.println("Item not found");
}
}
public void sellItem() {
printInLine();
System.out.println("nChoose item to mark as sold: ");
int id = in.nextInt();
if (items.containsKey(id)) {
items.get(id).setSold(true);
System.out.println("How much did you get for " + items.get(id).getName() + "?: ");
items.get(id).setSoldPrice(in.nextInt());
System.out.println("You marked " + items.get(id).getName() + " as sold");
System.out.println("Your profit is " + (items.get(id).soldPrice - items.get(id).price) + " PLN");
} else {
System.out.println("Item not found");
}
}
public void removeItem() {
printInLine();
System.out.println("nChoose item to remove: ");
int id = in.nextInt();
if (items.containsKey(id)) {
System.out.println(items.get(id).getName() + " removed");
items.remove(id);
} else {
System.out.println("Item not found");
}
}
public void bilans() {
int spendMoney = 0;
int earnedMoney = 0;
int profit = 0;
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().sold) {
spendMoney += entry.getValue().getPrice();
} else {
earnedMoney += entry.getValue().getSoldPrice();
profit += (entry.getValue().getSoldPrice() - entry.getValue().getPrice());
}
}
System.out.println("You have already spended: " + spendMoney + " PLN");
System.out.println("You sold items for: " + earnedMoney + " PLN");
System.out.println("Current profit: " + profit + " PLN");
if (earnedMoney > spendMoney) {
System.out.println("Wow, you are on +");
} else {
System.out.println("Keep trying");
}
}
public void details() {
printInLine();
System.out.print("nPick item: ");
int pickItem = in.nextInt();
if (items.containsKey(pickItem)) {
System.out.println("n| Details |");
System.out.println("Name: " + items.get(pickItem).getName() +
"nPrice: " + items.get(pickItem).getPrice() +
"nCondition: " + items.get(pickItem).getCondition() + "/10" +
"nColor: ");
} else {
System.out.println("Item not found");
}
}
private void printInLine() {
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().isSold()) {
System.out.print(" - " + entry.getKey() + "." + entry.getValue().getName());
}
}
}
}
java console e-commerce
edited 4 hours ago
Roman
700214
asked Feb 12 at 10:41
SharkmenSharkmen
61
$endgroup$
add a comment |
$begingroup$
I'm making note where you can add items that you buy or sell, any suggestions?
public class Main {
private static Scanner in = new Scanner(System.in);
private static String commands = "[-1]Quit, [0]Commands, [1]Available items, [2] Sold items, [3]Add, [4]Delete,"
+ " [5]Edit, [6]Sell. [7]Bilans [8]Details";
public static void main(String args) {
Storage storage = new Storage(5);
storage.addItem();
System.out.println("| RESELL NOTE |");
System.out.println(commands);
boolean flag = true;
while (flag) {
System.out.println("Choose option: (0 - print list)");
int answer = in.nextInt();
switch (answer) {
default:
System.out.println("Wrong command");
break;
case -1:
System.out.println("QUIT");
flag = false;
break;
case 0:
System.out.println(commands);
break;
case 1:
storage.availableItems();
break;
case 2:
storage.soldItems();
break;
case 3:
storage.addItem();
break;
case 4:
storage.removeItem();
break;
case 5:
System.out.println("modify item");
break;
case 6:
storage.sellItem();
break;
case 7:
storage.bilans();
break;
case 8:
storage.details();
}
}
}
}
public class Storage {
private int maxCapacity;
public Storage(int maxCapacity) {
this.maxCapacity = maxCapacity;
}
Scanner in = new Scanner(System.in);
private Map<Integer, Item> items = new TreeMap<>();
public void availableItems() {
System.out.println("Available items:");
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().sold) {
System.out.println(entry.getKey() + ". " + entry.getValue().getName());
}
}
}
public void soldItems() {
System.out.println("Sold items:");
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (entry.getValue().sold) {
System.out.println(entry.getKey() + "." + entry.getValue().getName()
+ " - (" + (entry.getValue().soldPrice - entry.getValue().price + "PLN profit)"));
}
}
}
public void addItem() {
if (items.size() >= maxCapacity) {
System.out.println("You cant add more items, storage full! (" + items.size() + "/" + maxCapacity + ")");
} else {
items.put(Item.assignId(), new Shoes("Piraty", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Belugi", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Zebry", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Creamy", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Sezame", 1500, 7, "red", 11));
System.out.println("Item added");
}
}
public void modifyItem() { // work in progress
printInLine();
System.out.println("nPick item to modify: ");
int id = in.nextInt();
if (items.containsKey(id)) {
System.out.println("Enter new name for " + items.get(id).getName());
in.nextLine();
String newName = in.nextLine();
items.get(id).setName(newName);
} else {
System.out.println("Item not found");
}
}
public void sellItem() {
printInLine();
System.out.println("nChoose item to mark as sold: ");
int id = in.nextInt();
if (items.containsKey(id)) {
items.get(id).setSold(true);
System.out.println("How much did you get for " + items.get(id).getName() + "?: ");
items.get(id).setSoldPrice(in.nextInt());
System.out.println("You marked " + items.get(id).getName() + " as sold");
System.out.println("Your profit is " + (items.get(id).soldPrice - items.get(id).price) + " PLN");
} else {
System.out.println("Item not found");
}
}
public void removeItem() {
printInLine();
System.out.println("nChoose item to remove: ");
int id = in.nextInt();
if (items.containsKey(id)) {
System.out.println(items.get(id).getName() + " removed");
items.remove(id);
} else {
System.out.println("Item not found");
}
}
public void bilans() {
int spendMoney = 0;
int earnedMoney = 0;
int profit = 0;
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().sold) {
spendMoney += entry.getValue().getPrice();
} else {
earnedMoney += entry.getValue().getSoldPrice();
profit += (entry.getValue().getSoldPrice() - entry.getValue().getPrice());
}
}
System.out.println("You have already spended: " + spendMoney + " PLN");
System.out.println("You sold items for: " + earnedMoney + " PLN");
System.out.println("Current profit: " + profit + " PLN");
if (earnedMoney > spendMoney) {
System.out.println("Wow, you are on +");
} else {
System.out.println("Keep trying");
}
}
public void details() {
printInLine();
System.out.print("nPick item: ");
int pickItem = in.nextInt();
if (items.containsKey(pickItem)) {
System.out.println("n| Details |");
System.out.println("Name: " + items.get(pickItem).getName() +
"nPrice: " + items.get(pickItem).getPrice() +
"nCondition: " + items.get(pickItem).getCondition() + "/10" +
"nColor: ");
} else {
System.out.println("Item not found");
}
}
private void printInLine() {
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().isSold()) {
System.out.print(" - " + entry.getKey() + "." + entry.getValue().getName());
}
}
}
}
java console e-commerce
edited 4 hours ago
Roman
700214
asked Feb 12 at 10:41
SharkmenSharkmen
61
$endgroup$
add a comment |
$begingroup$
I'm making note where you can add items that you buy or sell, any suggestions?
public class Main {
private static Scanner in = new Scanner(System.in);
private static String commands = "[-1]Quit, [0]Commands, [1]Available items, [2] Sold items, [3]Add, [4]Delete,"
+ " [5]Edit, [6]Sell. [7]Bilans [8]Details";
public static void main(String args) {
Storage storage = new Storage(5);
storage.addItem();
System.out.println("| RESELL NOTE |");
System.out.println(commands);
boolean flag = true;
while (flag) {
System.out.println("Choose option: (0 - print list)");
int answer = in.nextInt();
switch (answer) {
default:
System.out.println("Wrong command");
break;
case -1:
System.out.println("QUIT");
flag = false;
break;
case 0:
System.out.println(commands);
break;
case 1:
storage.availableItems();
break;
case 2:
storage.soldItems();
break;
case 3:
storage.addItem();
break;
case 4:
storage.removeItem();
break;
case 5:
System.out.println("modify item");
break;
case 6:
storage.sellItem();
break;
case 7:
storage.bilans();
break;
case 8:
storage.details();
}
}
}
}
public class Storage {
private int maxCapacity;
public Storage(int maxCapacity) {
this.maxCapacity = maxCapacity;
}
Scanner in = new Scanner(System.in);
private Map<Integer, Item> items = new TreeMap<>();
public void availableItems() {
System.out.println("Available items:");
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().sold) {
System.out.println(entry.getKey() + ". " + entry.getValue().getName());
}
}
}
public void soldItems() {
System.out.println("Sold items:");
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (entry.getValue().sold) {
System.out.println(entry.getKey() + "." + entry.getValue().getName()
+ " - (" + (entry.getValue().soldPrice - entry.getValue().price + "PLN profit)"));
}
}
}
public void addItem() {
if (items.size() >= maxCapacity) {
System.out.println("You cant add more items, storage full! (" + items.size() + "/" + maxCapacity + ")");
} else {
items.put(Item.assignId(), new Shoes("Piraty", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Belugi", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Zebry", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Creamy", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Sezame", 1500, 7, "red", 11));
System.out.println("Item added");
}
}
public void modifyItem() { // work in progress
printInLine();
System.out.println("nPick item to modify: ");
int id = in.nextInt();
if (items.containsKey(id)) {
System.out.println("Enter new name for " + items.get(id).getName());
in.nextLine();
String newName = in.nextLine();
items.get(id).setName(newName);
} else {
System.out.println("Item not found");
}
}
public void sellItem() {
printInLine();
System.out.println("nChoose item to mark as sold: ");
int id = in.nextInt();
if (items.containsKey(id)) {
items.get(id).setSold(true);
System.out.println("How much did you get for " + items.get(id).getName() + "?: ");
items.get(id).setSoldPrice(in.nextInt());
System.out.println("You marked " + items.get(id).getName() + " as sold");
System.out.println("Your profit is " + (items.get(id).soldPrice - items.get(id).price) + " PLN");
} else {
System.out.println("Item not found");
}
}
public void removeItem() {
printInLine();
System.out.println("nChoose item to remove: ");
int id = in.nextInt();
if (items.containsKey(id)) {
System.out.println(items.get(id).getName() + " removed");
items.remove(id);
} else {
System.out.println("Item not found");
}
}
public void bilans() {
int spendMoney = 0;
int earnedMoney = 0;
int profit = 0;
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().sold) {
spendMoney += entry.getValue().getPrice();
} else {
earnedMoney += entry.getValue().getSoldPrice();
profit += (entry.getValue().getSoldPrice() - entry.getValue().getPrice());
}
}
System.out.println("You have already spended: " + spendMoney + " PLN");
System.out.println("You sold items for: " + earnedMoney + " PLN");
System.out.println("Current profit: " + profit + " PLN");
if (earnedMoney > spendMoney) {
System.out.println("Wow, you are on +");
} else {
System.out.println("Keep trying");
}
}
public void details() {
printInLine();
System.out.print("nPick item: ");
int pickItem = in.nextInt();
if (items.containsKey(pickItem)) {
System.out.println("n| Details |");
System.out.println("Name: " + items.get(pickItem).getName() +
"nPrice: " + items.get(pickItem).getPrice() +
"nCondition: " + items.get(pickItem).getCondition() + "/10" +
"nColor: ");
} else {
System.out.println("Item not found");
}
}
private void printInLine() {
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().isSold()) {
System.out.print(" - " + entry.getKey() + "." + entry.getValue().getName());
}
}
}
}
java console e-commerce
edited 4 hours ago
Roman
700214
asked Feb 12 at 10:41
SharkmenSharkmen
61
$endgroup$
I'm making note where you can add items that you buy or sell, any suggestions?
public class Main {
private static Scanner in = new Scanner(System.in);
private static String commands = "[-1]Quit, [0]Commands, [1]Available items, [2] Sold items, [3]Add, [4]Delete,"
+ " [5]Edit, [6]Sell. [7]Bilans [8]Details";
public static void main(String args) {
Storage storage = new Storage(5);
storage.addItem();
System.out.println("| RESELL NOTE |");
System.out.println(commands);
boolean flag = true;
while (flag) {
System.out.println("Choose option: (0 - print list)");
int answer = in.nextInt();
switch (answer) {
default:
System.out.println("Wrong command");
break;
case -1:
System.out.println("QUIT");
flag = false;
break;
case 0:
System.out.println(commands);
break;
case 1:
storage.availableItems();
break;
case 2:
storage.soldItems();
break;
case 3:
storage.addItem();
break;
case 4:
storage.removeItem();
break;
case 5:
System.out.println("modify item");
break;
case 6:
storage.sellItem();
break;
case 7:
storage.bilans();
break;
case 8:
storage.details();
}
}
}
}
public class Storage {
private int maxCapacity;
public Storage(int maxCapacity) {
this.maxCapacity = maxCapacity;
}
Scanner in = new Scanner(System.in);
private Map<Integer, Item> items = new TreeMap<>();
public void availableItems() {
System.out.println("Available items:");
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().sold) {
System.out.println(entry.getKey() + ". " + entry.getValue().getName());
}
}
}
public void soldItems() {
System.out.println("Sold items:");
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (entry.getValue().sold) {
System.out.println(entry.getKey() + "." + entry.getValue().getName()
+ " - (" + (entry.getValue().soldPrice - entry.getValue().price + "PLN profit)"));
}
}
}
public void addItem() {
if (items.size() >= maxCapacity) {
System.out.println("You cant add more items, storage full! (" + items.size() + "/" + maxCapacity + ")");
} else {
items.put(Item.assignId(), new Shoes("Piraty", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Belugi", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Zebry", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Creamy", 1500, 7, "red", 11));
items.put(Item.assignId(), new Shoes("Sezame", 1500, 7, "red", 11));
System.out.println("Item added");
}
}
public void modifyItem() { // work in progress
printInLine();
System.out.println("nPick item to modify: ");
int id = in.nextInt();
if (items.containsKey(id)) {
System.out.println("Enter new name for " + items.get(id).getName());
in.nextLine();
String newName = in.nextLine();
items.get(id).setName(newName);
} else {
System.out.println("Item not found");
}
}
public void sellItem() {
printInLine();
System.out.println("nChoose item to mark as sold: ");
int id = in.nextInt();
if (items.containsKey(id)) {
items.get(id).setSold(true);
System.out.println("How much did you get for " + items.get(id).getName() + "?: ");
items.get(id).setSoldPrice(in.nextInt());
System.out.println("You marked " + items.get(id).getName() + " as sold");
System.out.println("Your profit is " + (items.get(id).soldPrice - items.get(id).price) + " PLN");
} else {
System.out.println("Item not found");
}
}
public void removeItem() {
printInLine();
System.out.println("nChoose item to remove: ");
int id = in.nextInt();
if (items.containsKey(id)) {
System.out.println(items.get(id).getName() + " removed");
items.remove(id);
} else {
System.out.println("Item not found");
}
}
public void bilans() {
int spendMoney = 0;
int earnedMoney = 0;
int profit = 0;
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().sold) {
spendMoney += entry.getValue().getPrice();
} else {
earnedMoney += entry.getValue().getSoldPrice();
profit += (entry.getValue().getSoldPrice() - entry.getValue().getPrice());
}
}
System.out.println("You have already spended: " + spendMoney + " PLN");
System.out.println("You sold items for: " + earnedMoney + " PLN");
System.out.println("Current profit: " + profit + " PLN");
if (earnedMoney > spendMoney) {
System.out.println("Wow, you are on +");
} else {
System.out.println("Keep trying");
}
}
public void details() {
printInLine();
System.out.print("nPick item: ");
int pickItem = in.nextInt();
if (items.containsKey(pickItem)) {
System.out.println("n| Details |");
System.out.println("Name: " + items.get(pickItem).getName() +
"nPrice: " + items.get(pickItem).getPrice() +
"nCondition: " + items.get(pickItem).getCondition() + "/10" +
"nColor: ");
} else {
System.out.println("Item not found");
}
}
private void printInLine() {
for (Map.Entry<Integer, Item> entry : items.entrySet()) {
if (!entry.getValue().isSold()) {
System.out.print(" - " + entry.getKey() + "." + entry.getValue().getName());
}
}
}
}
java console e-commerce
java console e-commerce
edited 4 hours ago
Roman
700214
asked Feb 12 at 10:41
SharkmenSharkmen
61
edited 4 hours ago
Roman
700214
asked Feb 12 at 10:41
SharkmenSharkmen
61
edited 4 hours ago
Roman
700214
edited 4 hours ago
Roman
700214
edited 4 hours ago
Roman
700214
700214
asked Feb 12 at 10:41
SharkmenSharkmen
61
asked Feb 12 at 10:41
SharkmenSharkmen
61
asked Feb 12 at 10:41
SharkmenSharkmen
61
61
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
Responsibilities
A class should have only one responsibility. Robert C. Martin describes it with
"There should never be more than one reason for a class to change".
When we have a look into Storage we can find multiple responsibilities:
- read inputs from the console
public void sellItem() {
// ..
int id = in.nextInt();
// ..
}
- provide the user with information
public void bilans() {
// ..
System.out.println("You have already spended: " + spendMoney + " PLN");
System.out.println("You sold items for: " + earnedMoney + " PLN");
System.out.println("Current profit: " + profit + " PLN");
// ..
}
- manage
items
Focus on one Responsibility
The class Storage should focus only on the logic to manage items.
Advantage Over Multiple Responsibilities
Multiple companies bought your tool. Now imagine the following two scenarios:
5 Years later Company A and B want different customized information. You can't find a class like InformationFormate. But after some search you found it in Storage, you go into it and change it. You built an if-statement to check for A or B and the default case to print some information.
Now company C calls you and sad that you should build them a graphical user interface. And again you go into the Storage after you didn't found a class like UserInterface and build a new if-statement to check for C and have build your gui logic into it and for all other the text user interface.
You can see, that with the number of responsibilities the number of possible changes grows for one class and it gets bigger and bigger. Additional when you search for these task you will not think at first that displaying information would be in a class named Storage.
Replace Conditional With Polymorphism
switch (answer) {
default:
System.out.println("Wrong command");
break;
case -1:
System.out.println("QUIT");
flag = false;
break;
case 0:
System.out.println(commands);
break;
case 1:
// ...
case 8:
storage.details();
}
What this huge switch tries to express is
Find a command by a number and execute the associated task.
We could simplyfy the switch with
Command command = commandFactory.getBy(answer);
boolean shouldContinueProgram = command.execute();
Factory Method Pattern
In the Unit above you found
Command command = commandFactory.provide(answer);
command.execute();
This is using the factory method pattern.
The commandFactory is an object which gives you the correct Instance of type Command, which is an interface and could be one of your 8 given commands to choose.
interface Command {
boolean execute();
}
class WrongInput implements Command {
@Override
public boolean execute() {
System.out.println("Wrong command");
return true;
}
}
class Quite implements Command {
@Override
public boolean execute() {
System.out.println("Wrong command");
return false;
}
}
interface CommandFactory<T> {
Command provide(T t);
}
class NumberCommandFactory implements CommandFactory<Integer> {
private Map<Integer, Command> numberByCommand;
public NumberCommandFactory() {
numberByCommand.put(-1, new Quite());
// ...
}
@Override
public Command provide(Integer numberOfCommand) {
return numberByCommand.getOrDefault(numberOfCommand, new WrongInput());
}
}
answered 6 hours ago
RomanRoman
700214
$endgroup$
add a comment |
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$begingroup$
Responsibilities
A class should have only one responsibility. Robert C. Martin describes it with
"There should never be more than one reason for a class to change".
When we have a look into Storage we can find multiple responsibilities:
- read inputs from the console
public void sellItem() {
// ..
int id = in.nextInt();
// ..
}
- provide the user with information
public void bilans() {
// ..
System.out.println("You have already spended: " + spendMoney + " PLN");
System.out.println("You sold items for: " + earnedMoney + " PLN");
System.out.println("Current profit: " + profit + " PLN");
// ..
}
- manage
items
Focus on one Responsibility
The class Storage should focus only on the logic to manage items.
Advantage Over Multiple Responsibilities
Multiple companies bought your tool. Now imagine the following two scenarios:
5 Years later Company A and B want different customized information. You can't find a class like InformationFormate. But after some search you found it in Storage, you go into it and change it. You built an if-statement to check for A or B and the default case to print some information.
Now company C calls you and sad that you should build them a graphical user interface. And again you go into the Storage after you didn't found a class like UserInterface and build a new if-statement to check for C and have build your gui logic into it and for all other the text user interface.
You can see, that with the number of responsibilities the number of possible changes grows for one class and it gets bigger and bigger. Additional when you search for these task you will not think at first that displaying information would be in a class named Storage.
Replace Conditional With Polymorphism
switch (answer) {
default:
System.out.println("Wrong command");
break;
case -1:
System.out.println("QUIT");
flag = false;
break;
case 0:
System.out.println(commands);
break;
case 1:
// ...
case 8:
storage.details();
}
What this huge switch tries to express is
Find a command by a number and execute the associated task.
We could simplyfy the switch with
Command command = commandFactory.getBy(answer);
boolean shouldContinueProgram = command.execute();
Factory Method Pattern
In the Unit above you found
Command command = commandFactory.provide(answer);
command.execute();
This is using the factory method pattern.
The commandFactory is an object which gives you the correct Instance of type Command, which is an interface and could be one of your 8 given commands to choose.
interface Command {
boolean execute();
}
class WrongInput implements Command {
@Override
public boolean execute() {
System.out.println("Wrong command");
return true;
}
}
class Quite implements Command {
@Override
public boolean execute() {
System.out.println("Wrong command");
return false;
}
}
interface CommandFactory<T> {
Command provide(T t);
}
class NumberCommandFactory implements CommandFactory<Integer> {
private Map<Integer, Command> numberByCommand;
public NumberCommandFactory() {
numberByCommand.put(-1, new Quite());
// ...
}
@Override
public Command provide(Integer numberOfCommand) {
return numberByCommand.getOrDefault(numberOfCommand, new WrongInput());
}
}
answered 6 hours ago
RomanRoman
700214
$endgroup$
add a comment |
$begingroup$
Responsibilities
A class should have only one responsibility. Robert C. Martin describes it with
"There should never be more than one reason for a class to change".
When we have a look into Storage we can find multiple responsibilities:
- read inputs from the console
public void sellItem() {
// ..
int id = in.nextInt();
// ..
}
- provide the user with information
public void bilans() {
// ..
System.out.println("You have already spended: " + spendMoney + " PLN");
System.out.println("You sold items for: " + earnedMoney + " PLN");
System.out.println("Current profit: " + profit + " PLN");
// ..
}
- manage
items
Focus on one Responsibility
The class Storage should focus only on the logic to manage items.
Advantage Over Multiple Responsibilities
Multiple companies bought your tool. Now imagine the following two scenarios:
5 Years later Company A and B want different customized information. You can't find a class like InformationFormate. But after some search you found it in Storage, you go into it and change it. You built an if-statement to check for A or B and the default case to print some information.
Now company C calls you and sad that you should build them a graphical user interface. And again you go into the Storage after you didn't found a class like UserInterface and build a new if-statement to check for C and have build your gui logic into it and for all other the text user interface.
You can see, that with the number of responsibilities the number of possible changes grows for one class and it gets bigger and bigger. Additional when you search for these task you will not think at first that displaying information would be in a class named Storage.
Replace Conditional With Polymorphism
switch (answer) {
default:
System.out.println("Wrong command");
break;
case -1:
System.out.println("QUIT");
flag = false;
break;
case 0:
System.out.println(commands);
break;
case 1:
// ...
case 8:
storage.details();
}
What this huge switch tries to express is
Find a command by a number and execute the associated task.
We could simplyfy the switch with
Command command = commandFactory.getBy(answer);
boolean shouldContinueProgram = command.execute();
Factory Method Pattern
In the Unit above you found
Command command = commandFactory.provide(answer);
command.execute();
This is using the factory method pattern.
The commandFactory is an object which gives you the correct Instance of type Command, which is an interface and could be one of your 8 given commands to choose.
interface Command {
boolean execute();
}
class WrongInput implements Command {
@Override
public boolean execute() {
System.out.println("Wrong command");
return true;
}
}
class Quite implements Command {
@Override
public boolean execute() {
System.out.println("Wrong command");
return false;
}
}
interface CommandFactory<T> {
Command provide(T t);
}
class NumberCommandFactory implements CommandFactory<Integer> {
private Map<Integer, Command> numberByCommand;
public NumberCommandFactory() {
numberByCommand.put(-1, new Quite());
// ...
}
@Override
public Command provide(Integer numberOfCommand) {
return numberByCommand.getOrDefault(numberOfCommand, new WrongInput());
}
}
answered 6 hours ago
RomanRoman
700214
$endgroup$
add a comment |
$begingroup$
Responsibilities
A class should have only one responsibility. Robert C. Martin describes it with
"There should never be more than one reason for a class to change".
When we have a look into Storage we can find multiple responsibilities:
- read inputs from the console
public void sellItem() {
// ..
int id = in.nextInt();
// ..
}
- provide the user with information
public void bilans() {
// ..
System.out.println("You have already spended: " + spendMoney + " PLN");
System.out.println("You sold items for: " + earnedMoney + " PLN");
System.out.println("Current profit: " + profit + " PLN");
// ..
}
- manage
items
Focus on one Responsibility
The class Storage should focus only on the logic to manage items.
Advantage Over Multiple Responsibilities
Multiple companies bought your tool. Now imagine the following two scenarios:
5 Years later Company A and B want different customized information. You can't find a class like InformationFormate. But after some search you found it in Storage, you go into it and change it. You built an if-statement to check for A or B and the default case to print some information.
Now company C calls you and sad that you should build them a graphical user interface. And again you go into the Storage after you didn't found a class like UserInterface and build a new if-statement to check for C and have build your gui logic into it and for all other the text user interface.
You can see, that with the number of responsibilities the number of possible changes grows for one class and it gets bigger and bigger. Additional when you search for these task you will not think at first that displaying information would be in a class named Storage.
Replace Conditional With Polymorphism
switch (answer) {
default:
System.out.println("Wrong command");
break;
case -1:
System.out.println("QUIT");
flag = false;
break;
case 0:
System.out.println(commands);
break;
case 1:
// ...
case 8:
storage.details();
}
What this huge switch tries to express is
Find a command by a number and execute the associated task.
We could simplyfy the switch with
Command command = commandFactory.getBy(answer);
boolean shouldContinueProgram = command.execute();
Factory Method Pattern
In the Unit above you found
Command command = commandFactory.provide(answer);
command.execute();
This is using the factory method pattern.
The commandFactory is an object which gives you the correct Instance of type Command, which is an interface and could be one of your 8 given commands to choose.
interface Command {
boolean execute();
}
class WrongInput implements Command {
@Override
public boolean execute() {
System.out.println("Wrong command");
return true;
}
}
class Quite implements Command {
@Override
public boolean execute() {
System.out.println("Wrong command");
return false;
}
}
interface CommandFactory<T> {
Command provide(T t);
}
class NumberCommandFactory implements CommandFactory<Integer> {
private Map<Integer, Command> numberByCommand;
public NumberCommandFactory() {
numberByCommand.put(-1, new Quite());
// ...
}
@Override
public Command provide(Integer numberOfCommand) {
return numberByCommand.getOrDefault(numberOfCommand, new WrongInput());
}
}
answered 6 hours ago
RomanRoman
700214
$endgroup$
Responsibilities
A class should have only one responsibility. Robert C. Martin describes it with
"There should never be more than one reason for a class to change".
When we have a look into Storage we can find multiple responsibilities:
- read inputs from the console
public void sellItem() {
// ..
int id = in.nextInt();
// ..
}
- provide the user with information
public void bilans() {
// ..
System.out.println("You have already spended: " + spendMoney + " PLN");
System.out.println("You sold items for: " + earnedMoney + " PLN");
System.out.println("Current profit: " + profit + " PLN");
// ..
}
- manage
items
Focus on one Responsibility
The class Storage should focus only on the logic to manage items.
Advantage Over Multiple Responsibilities
Multiple companies bought your tool. Now imagine the following two scenarios:
5 Years later Company A and B want different customized information. You can't find a class like InformationFormate. But after some search you found it in Storage, you go into it and change it. You built an if-statement to check for A or B and the default case to print some information.
Now company C calls you and sad that you should build them a graphical user interface. And again you go into the Storage after you didn't found a class like UserInterface and build a new if-statement to check for C and have build your gui logic into it and for all other the text user interface.
You can see, that with the number of responsibilities the number of possible changes grows for one class and it gets bigger and bigger. Additional when you search for these task you will not think at first that displaying information would be in a class named Storage.
Replace Conditional With Polymorphism
switch (answer) {
default:
System.out.println("Wrong command");
break;
case -1:
System.out.println("QUIT");
flag = false;
break;
case 0:
System.out.println(commands);
break;
case 1:
// ...
case 8:
storage.details();
}
What this huge switch tries to express is
Find a command by a number and execute the associated task.
We could simplyfy the switch with
Command command = commandFactory.getBy(answer);
boolean shouldContinueProgram = command.execute();
Factory Method Pattern
In the Unit above you found
Command command = commandFactory.provide(answer);
command.execute();
This is using the factory method pattern.
The commandFactory is an object which gives you the correct Instance of type Command, which is an interface and could be one of your 8 given commands to choose.
interface Command {
boolean execute();
}
class WrongInput implements Command {
@Override
public boolean execute() {
System.out.println("Wrong command");
return true;
}
}
class Quite implements Command {
@Override
public boolean execute() {
System.out.println("Wrong command");
return false;
}
}
interface CommandFactory<T> {
Command provide(T t);
}
class NumberCommandFactory implements CommandFactory<Integer> {
private Map<Integer, Command> numberByCommand;
public NumberCommandFactory() {
numberByCommand.put(-1, new Quite());
// ...
}
@Override
public Command provide(Integer numberOfCommand) {
return numberByCommand.getOrDefault(numberOfCommand, new WrongInput());
}
}
answered 6 hours ago
RomanRoman
700214
answered 6 hours ago
RomanRoman
700214
answered 6 hours ago
RomanRoman
700214
answered 6 hours ago
RomanRoman
700214
700214
add a comment |
add a comment |
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