我不知道怎么表达了，我做了一个demo大家看一下能不能实现啊
Generic.java

public class Generic<T> {
    private T key;

    public Generic(T key) {
        this.key = key;
    }

    public T getKey() {
        return key;
    }
}

Hello.java

public class Hello {
    public static void main(String[] args) {
        Generic<Integer> genericInteger = new Generic<>(123456);
        Generic<String> genericString = new Generic<>("key_value");

        System.out.println("key is " + doWithGeneric(genericInteger));
        System.out.println("key is " + doWithGeneric(genericString));
    }

    public static String doWithGeneric(Generic<Object> generic) {
        return generic.getKey().toString();
    }
}

但现在提示如下错误：

项目的源代码我传上来了，请大神指点一二

找到解决办法了

要注明类别  extends ...