How to check if a Java object is final

February 03, 2023

How to check if a Java object is final

final modifier can be applied at class level. If a Class is marked final it cannot be extended.
Sample final Class

final class MyCustomClass {
	
}

Using java.lang.reflect.Modifier

Using java.lang.reflect.Modifier,, We can check if a class is final though java.lang.reflect.Modifier.isFinal() method. MyCustomClass.class.getModifiers() will provide an integer number representing the class modifier. For example for the above class it prints 16. Now the value returned from the getModifiers() can be decoded with method Modifier.isFinal();
JavaReflectionModifiers
import java.lang.reflect.Modifier;

public class JavaReflectionModifiers {

	public static void main(String[] args) {
		
                 //prints 16
		System.out.println(MyCustomClass.class.getModifiers());
		
                 //returns true
		Modifier.isFinal(MyCustomClass.class.getModifiers());

	}

}


final class MyCustomClass {
	
}

More Examples

Examples
package Java14;

import java.lang.reflect.Modifier;

public class JavaReflectionModifiers {

	public static void main(String[] args) {
		
		System.out.println(MyCustomClass.class.getModifiers());
		
		//prints true
		System.out.println(Modifier.isFinal(MyCustomClass.class.getModifiers()));
		
		//prints true
		System.out.println(Modifier.isFinal(String.class.getModifiers()));
		
		//prints false
		System.out.println(Modifier.isFinal(Number.class.getModifiers()));

	}

}


final class MyCustomClass {
	
}
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