Java优学网泛型类教程：轻松掌握类型安全与代码复用，告别繁琐转型

public class Container {

private T value;

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

public T getValue() {
    return value;
}

}

public class Wrapper {

private T content;

public Wrapper(T content) {
    this.content = content;
}

public T getContent() {
    return content;
}

public void setContent(T content) {
    this.content = content;
}

}

public class GenericStack {

private List<T> elements = new ArrayList<>();

public void push(T element) {
    elements.add(element);
}

public T pop() {
    if (elements.isEmpty()) {
        return null;
    }
    return elements.remove(elements.size() - 1);
}

public boolean isEmpty() {
    return elements.isEmpty();
}

}

public class SimpleCache<K, V> {

private Map<K, V> cache = new HashMap<>();

public void put(K key, V value) {
    cache.put(key, value);
}

public V get(K key) {
    return cache.get(key);
}

}

public void printList(List<?> list) {

for (Object item : list) {
    System.out.println(item);
}

}

// 泛型之前 List list = new ArrayList(); list.add("hello"); String str = (String) list.get(0); // 需要显式转型

// 使用泛型后 List list = new ArrayList<>(); list.add("hello"); String str = list.get(0); // 自动类型推断