Thread safety of static blocks in Java

Question

Let\'s say I have some Java code:

public class SomeClass {
    static {
        private final double PI = 3.14;
        private final double SOME_CONSTANT =          


        

Answer 1

If the first thread hasn't finished initializing SomeClass, the second thread will block.

This is detailed in the Java Language Specification in section 12.4.2.

Answer 2

watch out that you dont call code that require the lock for the class being initialized - it will deadlock. see this blog post: http://ramblingabout.wordpress.com/2008/04/10/deadlock-quiz-the-answer/

Answer 3

Static class initialization is guaranteed to be thread-safe by Java.

Answer 4

Static block is always thread safe while its getting initialzed. This is the reason use static variable of singleton object as one way of creating singleton object (singelton desing pattern).