Java.lang.reflect.Constructor thread safe ?

Question

When you have a Constructor object in Java.
Is calling the newInstance method on the same Constructor object from multiple threads safe.
Or is this not thread safe leading to wrongly constructed objects?

Answer 1

ejp wrote:
And as Constructors are immutable, it's hard to see how it's going to get altered.Constructors are basically immutable, but they have at least one state which can make the difference between newInstance working or failing.
As you can see in the following example, setAccessible() is not something you would want to set to different values in different threads.
import java.lang.reflect.Constructor;
public class Main {
    public static void main(String... args) throws Exception {
        Constructor cons = Private.class.getDeclaredConstructor();
        cons.setAccessible(false);
        try {
            System.out.println("cons.isAccessible()= " + cons.isAccessible());
            cons.newInstance();
            throw new AssertionError("IllegalAccessException expected");
        } catch (IllegalAccessException expected) {
            // ignored
        cons.setAccessible(true);
        System.out.println("cons.isAccessible()= " + cons.isAccessible());
        cons.newInstance();
class Private {
    private Private() {
}