How to Replace Class.newInstance in Java 9 and Beyond

What are the best alternatives to Class.newInstance in Java 9?

Class<?> clazz = MyClass.class;
Constructor<?> constructor = clazz.getDeclaredConstructor();
Object instance = constructor.newInstance();

In Java 9 and later, the `Class.newInstance` method has been deprecated due to its limitations, such as lack of exception handling. This guide explores safer and more flexible alternatives to instantiate classes dynamically.

try {
    Class<?> clazz = MyClass.class;
    Constructor<?> constructor = clazz.getDeclaredConstructor();
    Object instance = constructor.newInstance();
} catch (NoSuchMethodException | InstantiationException | IllegalAccessException | InvocationTargetException e) {
    e.printStackTrace();
}

Causes

• Lack of exception handling when instantiating objects.
• Potential issues with accessing private constructors.
• The method may lead to security vulnerabilities.

Solutions

• Use `Constructor<T>.newInstance()` method for safer instantiation.
• Leverage `Reflection.newInstance()` method for better control.
• Utilize dependency injection frameworks when appropriate.

Mistake: Forgetting to handle exceptions when using reflection methods.

Solution: Always use try-catch blocks to handle exceptions and ensure your code is robust.

Mistake: Using `newInstance()` directly without checking accessibility.

Solution: Get the constructor using `getDeclaredConstructor()` and set it accessible if needed.