java code snippets for practice

MyBusinessException("A message that describes the error.", e); }} Therefore, only when you want to handle the exception to capture, otherwise only need to declare in the method signature let the caller to handle.9. Do not discard the original exception when packing the exceptionCapturing standard exceptions and wrapping them as custom exceptions is a common practice. This allows you to add more specific exception information and be able to

Time flies really fast, a blink of an eye,ten days passed, feel the last time to write the scene of reading notes as if still vivid. "Code reading Method and Practice" This book is really difficult to write notes, originally I read the name of the book is probably written in the book is a simple way to read the code, thinking that this is good to write notes, did

[Java project practice] dom4j parses xml files, connects to the Oracle database, and dom4joracleIntroduction Dom4j is an open source XML parsing package produced by dom4j.org. This sentence is too official. Let's take a look at the official explanation. For example: Dom4j is an easy-to-use, open-source library for parsing XML, XPath, XSLT, and other languages. It is applied to the

basic integer. For modifiable objects, the answer is not always so clear.equals()AndhashCode()Should the status of the object be based on the identifier of the object (such as the default implementation) or the object (such as integer and string )? There is no simple answer-it depends on the plan of the class. ForListAndMapFor such containers, people are arguing about this. Most classes in the Java class library, including the container class. errors

Telescopic Content: Synchronized Quick Review The improvement of the synchronized Compare the scalability of Reentrantlock and synchronized Condition variable It's not fair Conclusion Resources About the author The evaluation of the paper Related content: Java Theory and Practice series Synchronization is not the enemy Reducing contention IBM developer Kits for the

application of this pattern is exceeded, it will become very difficult to combine these two competing synchronization mechanisms. Conclusion Compared with the lock, the volatile variable is a very simple but fragile synchronization mechanism that will provide better performance and scalability than the lock in some cases. If you strictly follow the volatile usage conditions-that is, variables are truly independent from other variables and their previous values-in some cases, you can usevolatile

failed; Nested exception is java.lang.RuntimeException: has been to set current limit times] with root causejava.lang.RuntimeException: already to set current limit times at COM. Souyunku.example.config.LimitAspect.interceptor (limitaspect.java:73) ~[classes/:na] at Sun.reflect.GeneratedMethodAccessor35.invoke (Unknown Source) ~[na:na] at Sun.reflect.DelegatingMethodAccessorImpl.invoke (delegatingmethodaccessorimpl.java:43) ~[na:1.8.0_112] at Java.lang.reflect.Method.invoke (method.java:498) ~[

Baptism of the soul, practice python (3) -- expose coding problems, operating principles and syntax habits from a simple print code, pythonprint After the preliminary work is ready, you can open the IDE editor. You can select the built-in python IDLE or a third party. Here I use pycharm-an IDE dedicated to python. By convention, "hello, world" is required for printing the first python

,jni_version_1_4)!=JNI_OK){return-1;}Jclass jthiz = Env->findclass (ClassPath);if (Env->registernatives (Jthiz,methods,sizeof (methods)/sizeof (Methods[0])) {return-1;}return jni_version_1_4;}As can be seen from the above code, the JNI layer through the Pthread library to complete the creation of threads, it is important to note that the JNI layer of the thread, must be through the global JAVAVM to get to the environment variables, but also through th

After the use of Zabbix for monitoring, often because of the requirements of the project, the need for Zabbix data, two times to share and develop. How to obtain data from Zabbix is a problem to be solved in this practice. There are two ways to Zabbix data sharing 1 through the database query, get the data. The premise is to have a deep understanding of the Zabbbix database model, and in a large number of monitoring, can not because the query affect t

cases provides better performance and scalability than locks. If you strictly follow the use of volatile conditions-that is, the variable is really independent of the other variables and its own previous values-in some cases you can use the volatile substitution synchronized to simplify the code. However, volatile the code used is often more error-prone than code