Which method is used to create an instance of a class using its constructor with Java Reflection?

Java MCQ: Which method is used to create an instance of a class using its constructor with Java Reflection?

Answer:

Explanation:

The newInstance() method in Java is used to create a new instance of a class using its constructor via reflection. This method is part of the Constructor class, which is found in the java.lang.reflect package. newInstance() allows you to instantiate a class dynamically at runtime, even if the class name or constructor is not known at compile-time.

Here’s an example of how to use newInstance() to create a new instance of a class:

import java.lang.reflect.Constructor;

public class CreateInstanceExample {
    public static void main(String[] args) {
        try {
            Constructor<MyClass> constructor = MyClass.class.getConstructor(String.class);
            MyClass obj = constructor.newInstance("Hello, World!");
            obj.displayMessage();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

class MyClass {
    private String message;

    public MyClass(String message) {
        this.message = message;
    }

    public void displayMessage() {
        System.out.println(message);
    }
}

In this example, the getConstructor() method is used to obtain a Constructor object representing the constructor of the MyClass class that takes a String argument. The newInstance() method is then called on the constructor object to create a new instance of MyClass, passing the string "Hello, World!" as an argument. The new instance is then used to call the displayMessage() method.

The newInstance() method is a crucial part of Java Reflection, allowing developers to create objects dynamically, which is particularly useful in scenarios such as dependency injection, object serialization, and testing frameworks.

Reference links:

https://www.rameshfadatare.com/learn-java-programming/
https://www.javaguides.net/p/java-tutorial-learn-java-programming.html