You can replace all occurrence of a single character, or a substring of a given String in Java using the replaceAll() method of java.lang.String class. This method also allows you to specify the target substring using the regular expression, which means you can use this to remove all white space from String. The replaceAll() function is very useful, versatile and powerful method and as a Java developer, you must know about it. Even though Java provides separate methods for replacing characters and replacing substring, you can do all that just by using this single method. The replaceAll() method replaces each substring of this string (the String on which it is called) that matches the given regular expression with the given replacement. It internally uses classes like Pattern and Matcher from java.util.regex package for searching and replacing matching characters or substring.
I have been sharing programming books in this blog from a long time, starting with core Java, I moved to other related technology e.g. Spring, Design patterns, Data Structure and Algorithms etc. Today, I am going to share some of the best UNIX and Linux programming books. The list contains some of the must read UNIX books from great writers like Sir Richard. Stevens, Sir Brain Kernighan, who has contributed so much to the development of UNIX operating system. Most of the books in this list are timeless, classics and don't age with time, much like UNIX, which is around from last 40 years and I am sure will be around for next 40 years, or maybe forever.
The OCEJWCD is the Oracle's version of SCWCD (Sun Certified Web Component Developer) exam, which tests candidate's knowledge on Servlet, JSP, and other web technology. The OCEJWCD stands for Oracle Certified Enterprise Java Web Component Developer. Like other Java certifications e.g. OCAJP or OCPJP, the key to success is selecting a good book, practicing code daily, and then solving as many mock questions as possible. In the last article, I have shared some of the best OCEJWCD books and in this article, I am going to share of the best free OCEJWCD 6 mock tests you can online. These mock exams are good for self-assessment and practicing before real exams.