markdown-it demo

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```java
public class GenericClass<T> {
    private T value;

public GenericClass(T value) {
        this.value = value;
    }

public T getValue() {
        return value;
    }

public void setValue(T value) {
        this.value = value;
    }

public static <E> void genericMethod(E item) {
        System.out.println("Generic Method: " + item);
    }

public static void main(String[] args) {
        // 使用泛型類
        GenericClass<String> stringClass = new GenericClass<>("Hello");
        System.out.println("Generic Class Value: " + stringClass.getValue());

// 使用泛型方法
        GenericClass.genericMethod(10);
    }
}
```

### 通配符(Wildcard)
```java
import java.util.ArrayList;
import java.util.List;

public class GenericWildcardExample {
    public static void printList(List<?> list) {
        for (Object item : list) {
            System.out.println(item);
        }
    }

public static void main(String[] args) {
        List<String> stringList = new ArrayList<>();
        stringList.add("Hello");
        stringList.add("World");

List<Integer> integerList = new ArrayList<>();
        integerList.add(10);
        integerList.add(20);

printList(stringList);
        printList(integerList);
    }
}
```

### 泛型限定(Bounds)
```java
public class GenericBoundsExample {
    public static <T extends Number> double sum(List<T> list) {
        double total = 0.0;
        for (T number : list) {
            total += number.doubleValue();
        }
        return total;
    }

public static void main(String[] args) {
        List<Integer> integerList = Arrays.asList(1, 2, 3, 4, 5);
        double sum1 = sum(integerList);
        System.out.println("Sum of integers: " + sum1);

List<Double> doubleList = Arrays.asList(1.1, 2.2, 3.3, 4.4, 5.5);
        double sum2 = sum(doubleList);
        System.out.println("Sum of doubles: " + sum2);

// 編譯錯誤，String 類型不符合限定條件
        // List<String> stringList = Arrays.asList("one", "two", "three"); 
    }
}
```

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