What is the concept of downward transformation in java

Concept

1. Downward transformation is the conversion of parent class objects into subclass objects. We give a reference of the Animal type from the parent class to a Bird type reference. This is a downward transformation.

2. The format is

子类 子类对象=（子类）父类实例

Note

Be sure to perform forced type conversion when converting downward

Example

class Animal {
    public String name;
    public void eat() {
        System.out.println(this.name + " 正在吃");
    }
}
class Cat extends Animal {
 
}
class Bird extends Animal {
    public int age;
    public void fly() {
        System.out.println(this.name+"起飞");
    }
}
public class Test extends TestDemo {
    public static void main(String[] args) {
        Animal animal = new Animal();
        Bird bird = (Bird) animal;//必须进行强制类型转换
    }
}

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