The common way to create objects in Java is by using public constructors. A class provides public constructor e.g. java.lang.String so anyone can create an instance of String class to use in their application, but, there is another technique which can be used to create objects in Java and every experienced Java programmer should know about it. A class can provide a public static factory method which can return an instance of the class e.g. HashMap.newInstance(). The factory method is a smart way to create objects in Java and provides several advantages over the traditional approach of creating objects using constructors in Java. It can also improve the quality of code by making the code more readable, less coupled, and improves performance by caching.
The volatile modifier has always been an interesting and tricky topic to many Java programmers. I still feel that it's one of the most underutilized modifiers in Java, which can do a lot of good if understood and applied correctly, after all, it provides a lock-free way to achieve synchronization in Java. If a field is shared between multiple threads and one of them change its value i.e. one thread reads from the field which is written by other threads, then, by using a volatile modifier, you can synchronize access to this field. The volatile modifier in Java provides visibility and ordering guarantee without any locking. You might know that compiler and JVM can re-order your code due to various reasons e.g. performance improvement which can be a problem in concurrent Java application.
Labels: Java multithreading Tutorials