Java implementation of operation code that converts Object into a specified Class object

In Java,ObjectConvert to a specified typeClassObjects are actually operations of two different concepts:

1. WillObjectConvert instances to instances of a specific type: This usually involves type conversion (e.g.(MyType) myObject) or through reflection mechanism ((Object)) to carry out.
2. Get a specific type ofClassObject: This can be passed.classSyntax or(String className)Method implementation.

Since the "converting Object to a specified Class object" you mentioned may be a bit confusing, I will show the sample code for both operations separately.

Example 1: Convert an Object instance to an instance of a specific type

First, we define a simple class and a transformation example:

class Animal {  
    void eat() {  
        ("This animal eats.");  
    }  
}  
  
class Dog extends Animal {  
    void bark() {  
        ("Woof!");  
    }  
}  
  
public class Main {  
    public static void main(String[] args) {  
        // Suppose we have an Object instance, which is actually Dog type        Object myDog = new Dog();  
  
        // Try to convert Object to Dog type        if (myDog instanceof Dog) {  
            Dog dog = (Dog) myDog;  
            ();  
            (); // Inherited from Animal        } else {  
            ("Not a dog!");  
        }  
  
        // Example using() (actually similar to direct conversion, but more general)        try {  
            Dog anotherDog = (Dog) ("Dog").cast(myDog);  
            ();  
        } catch (ClassNotFoundException e) {  
            ();  
        }  
    }  
}  
  
// Note: The above ("Dog") will throw a ClassNotFoundException because "Dog" is not a fully qualified class name.// The correct way is to use fully qualified class names, such as "", and this is usually not a recommended way to dynamic type conversion.

Notice：("Dog").cast(myDog)This usage is actually not recommended becausecastMethods are not more than direct type conversion(Dog) myDogProvide more features, andA fully qualified class name is required.

Example 2: Get a Class object of a specific type

public class Main {  
    public static void main(String[] args) {  
        // Use .class syntax to get Class object        Class<Dog> dogClass = ;  
        (()); // Output: (assuming Dog is under the package)  
        // Use to get Class object (note exception handling)        try {  
            Class<?> cls = ("");  
            (()); // Same output:        } catch (ClassNotFoundException e) {  
            ();  
        }  
    }  
}  
  
// Assume that the Dog class is under package

Note: The method requires a fully qualified class name and a ClassNotFoundException will be thrown if the specified class cannot be found. Additionally, since the returned Class<?> is a wildcard type Class object, if you know the specific type, it is best to use the .class syntax to avoid unnecessary type conversion.

The above example shows in detail how to convert an Object instance to a specific type of instance in Java, and how to get a Class object of a specific type.

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