无法将接口的xx方法 应用到给定类型

interface MyInterface {
    void myMethod();
}

class MyClass implements MyInterface {
    @Override
    public void myMethod() {
        // 实现方法
    }
}

MyInterface obj = new MyClass(); // 正确
// MyInterface obj = new Object(); // 错误，Object类没有实现MyInterface

interface MyGenericInterface<T> {
    void process(T item);
}

class MyGenericClass<T> implements MyGenericInterface<T> {
    @Override
    public void process(T item) {
        // 实现方法
    }
}

Object obj = new MyClass();
if (obj instanceof MyInterface) {
    MyInterface myObj = (MyInterface) obj;
    myObj.myMethod();
}

interface Drawable {
    void draw();
}

class Shape { // 缺少draw方法的实现
}

Shape shape = new Shape();
Drawable drawable = (Drawable) shape; // 运行时错误：ClassCastException
drawable.draw(); // 不会执行到这里

class Shape implements Drawable {
    @Override
    public void draw() {
        System.out.println("Drawing a shape.");
    }
}

Shape shape = new Shape();
Drawable drawable = shape;
drawable.draw(); // 输出: Drawing a shape.