home.md

@@ -20,4 +20,94 @@
 public static int main(String[] args)
 ```
 
-- 
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+- 
+
+```java
+package com.company;
+
+import java.util.ArrayList;
+import java.util.stream.Collectors;
+
+class Fruit {
+    private String name;
+    private int price;
+
+    Fruit(String name, int price) {
+        this.name = name;
+        this.price = price;
+    }
+
+    int getPrice() {
+        return price;
+    }
+
+    String getName() {
+        return name;
+    }
+}
+
+class Dealer {
+
+}
+
+class FruitDealer extends Dealer {
+
+    final private ArrayList<Fruit> fruits;
+
+    FruitDealer(ArrayList<Fruit> fruits) {
+        this.fruits = fruits;
+    }
+
+    ArrayList<String> getFruitsNames() {
+        return fruits
+                .stream()
+                .map(Fruit::getName)
+                .collect(Collectors.toCollection(ArrayList::new));
+    }
+
+    int getFruitPrice(String fruitsName) {
+        return fruits.stream()
+                .filter(f -> f.getName().equals(fruitsName))
+                .findFirst()
+                .orElse(null)
+                .getPrice();
+    }
+
+    int buyFruit(String fruitName, int money) {
+        int fruitPrice = this.getFruitPrice(fruitName);
+        if (money > fruitPrice) {
+            return money - fruitPrice;
+        }
+        return money;
+    }
+}
+
+
+public class Main {
+
+    private final static String WHAT_I_WANT_FRUIT = "바나나";
+
+    public static void main(String[] args) {
+        int myMoney = 500;
+
+        FruitDealer fruitDealer = new FruitDealer(new ArrayList<Fruit>() {{
+            add(new Fruit("사과", 300));
+            add(new Fruit("바나나", 200));
+            add(new Fruit("포도", 400));
+        }});
+
+        String fruitName = fruitDealer.getFruitsNames().stream()
+                .filter(s -> s.equals(WHAT_I_WANT_FRUIT))
+                .findFirst()
+                .orElse(null);
+
+        int fruitPrice = fruitDealer.getFruitPrice(fruitName);
+
+        if (myMoney > fruitPrice) {
+            myMoney = fruitDealer.buyFruit(fruitName, myMoney);
+        }
+
+        System.out.println(myMoney);
+    }
+}
+```
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