java code snippets for practice

Once an object is created, it will no longer change its contents, so that the object is immutable. This can be done without worrying about competition management when accessing objects in multiple threads, and Java's string is an example of an immutable object. Based on this, when you use Scala to create multithreaded applications, you can write unlocked code with the invariant state (immutable states) to write concise multithreaded

constructor is set to private, default, or protected level.　　Four Serialization compatibility for different versions of serializable classesAny class that implements the Serializable interface has a static variable that represents the serialized version identifier:Private static final long serialversionuid;The value of the above serialversionuid is generated automatically by the Java Runtime Environment based on the internal details of the class. If

. volatilevariables are not cached in registers or in places that are not visible to other processors, so the volatile most recently written value is always returned when a variable of type is read.volatileYou should use variables only if they simplify the implementation of your code and validate your synchronization policies. If you need to make complex judgments about visibility when validating correctness, do not use volatile variables. volatilethe

parse the system code path, including the LIBJVM internal, GC, and kernel, but not Java methods, such as HPROF, lightweight Java parsers, and other business analyzers, which can display Java methods, However, the system code path cannot be displayed. Thus, neither of these

2. binary representation of numeric valuesAfter-school exercise: read the corresponding textbook, or use the Internet search engine, to find out the anti-code, complement and the original code of the concepts, and then write a sample program, the positive numbers, negative numbers for a variety of bit operations, observe the output, and the results of the manual calculation, to see the number in

Address: http://blog.csdn.net/kongxx/article/details/7259827 One of Java Socket practices: Single-thread Communication Java Socket practice 2 multi-thread Communication Previous two articlesArticleThis article describes how to establish Java Socket communication, and describes how to use

Http://www.ibm.com/developerworks/cn/java/j-jtp06197.htmlThe Java™ language contains two intrinsic synchronization mechanisms: synchronous blocks (or methods) and volatile variables. Both of these mechanisms are proposed to achieve the security of code threads. Where volatile variables are less synchronous (but sometimes simpler and less expensive), and their use

Guidelines for using volatile variablesThe Java™ language contains two intrinsic synchronization mechanisms: synchronous blocks (or methods) and volatile variables. Both of these mechanisms are proposed to achieve the security of code threads. Where volatile variables are less synchronous (but sometimes simpler and less expensive), and their use is more error-prone. In this period of

only need to write some packages that can achieve our goal, we will adjust it based on our specific needs ". However, it is often because you have quickly extended the compiled simple tool and tried to add more features until you compile a complete infrastructure service. At this point, you usually stick to the program you write, whether it is good or bad. You have already paid all the cost for building your own program, so in addition to the actual migration cost invested by the general implem

" 0000 system.out.println (integer.tohexstring ( -128)); //ffffff80 //(-128 0xFF) Complement: 1111 1111 1111 1111 1111 1111" 0000 0000 0000 0000 0000 0000 0000 1111 1111 = 0000 0000 0000 0000 0000 0000" 0000 system.out.println (integer.tohexstring ( -128 0xFF)); //00000080 //byte byte_128 = (byte) -128 (---128 complement reserved last 8--0000) //byte_128 complement: 0000 //byte_128:1111 1111 (symbol bit invariant remaining bit reversed) //byte_128

eventually crush the product, we did lose a customer.What's worse than a program crash?So far, I have found that Java's exception handling has been broken by most of us, the ubiquitous try catch can be seen dizzy, in order to ensure the "robustness" of the program, considering the user experience, we put the wrong layer of packaging, when encountered errors, We are very friendly to prompt users to wait patiently, which in many cases, so that users feel helpless.See the author of this article, t

components of the project, such as src, target, and lib, if you know which development environment you want to adapt to in the command, you can convert it. This provides some flexibility for specific development. Maven provides the plug-in for converting to the mainstream environment eclipse maven-eclipse-plugin, the corresponding conversion command is eclipse: eclipse. IDEA also provides the maven-IDEA-plugin plug-in for idea conversion, and the command for converting to the corresponding deve