java practice exam

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

[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

Each Java object has a hashcode () and Equals () method. Many classes ignore (Override) default implementations of these methods to provide deeper semantic comparability between object instances. In the Java Philosophy and Practice section, Java Developer Brian Goetz introduces you to the rules and guidelines you shoul

design. Back to top of pageConclusionThrough a unified definition equals() and you can promote the usability of a hashCode()， class as a keyword in a hash-based collection. There are two ways to define equality and hash values for an object: based on identity, which is the Object default method provided, and based on state, which requires Override equals() and hashCode() . When the state of an object changes, if the hash value of the object changes, you are sure that you are not allowed to cha

Java Theory and Practice: block memory leakage with weak referencesWeak references make it easy to express object lifecycle relationships. Document options

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

Scala, inheriting a base class is similar to Java, with a two-point limit, and (1) Overriding the method requires the Override keyword, (2) only the primary constructor can pass parameters to the base class constructor. Markerfactory is a single case, once the definition is complete, its name represents the only instance of the singleton object, and the singleton can be passed to the function as if it were a typical passing instance.

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

Each Java object has a hashcode () and Equals () method. Many classes ignore (Override) default implementations of these methods to provide deeper semantic comparability between object instances. In the Java Philosophy and Practice section, Java Developer Brian Goetz introduces you to the rules and guidelines you shoul

Java handles a little practice of excel in the accumulationTong Liang Date: 2008-11-061 Document DescriptionPurpose: The main purpose of this document is to share with you how to work with Excel in Java, part of the code from the Enterprise project management system V2.0 Source, part of the copy online.Background: Colleagues working with the Windows operating sys

Java5 adds a new class library concurrency set Java.util.concurrent, which provides rich APIs for concurrent programs that are easier and more flexible in Java 5. This article through a network server model, to practice JAVA5 multithreaded programming, the model used in the JAVA5 thread pool, blocking queues, can be reset locks, but also practice callable, future

In the previous article on the LIBSVM process and the simple Java code test to explain, this article is simple to libsvm how to practice in the project short description, inappropriate places welcome you to correct.The first step is to adjust the predictive function of LIBSVM, and I'm taking some of the code from the Svm_predict class to make predictive defenses, the code is as follows:/*** Classify incomin

outstanding open source Concurrency Toolkit, java.util.concurrent, which contains mutex, trust, and performance-performing collection classes such as queues and hash tables, and some work queue implementations under concurrent access. The Pooledexecutor class in this package is an efficient, widely used, and correct implementation of a thread pool based on a work queue. Instead of trying to write the code yourself, it's easy to make mistakes, and you can consider using some of the tools in the

Never thought, "Java Array conversion to list" unexpectedly have so many knowledge, shock and entrainment a little unbearable. About "Java Array conversion to list" is actually very basic knowledge, and there are a lot of people in the blog has been discussed, it is inevitable that I feel that writing such a discussion article how much is not necessary! On second thought, "Do not accumulate silicon step, no

13.3% Design 2h 26.6% Code implementation 4h 53.3% Test 0 0 Analysis Summary 30min 6.7% Experimental Summary (no pairing game programming)The most practical knowledge learned through this experiment is the use of refactoring Raname: How to modify a name. It is an improvement in eclipse, and is now quick and easy to modify, when the name is accidentally misspelled at the time of th

Time: 32 Time: 15 3 Time: 50 Time: 57 Time: 39 Time: 21 4 Time: 47 Time: 31 Time: 39 Time: 14 Can be summarized as follows: Iterate keys and search values very inefficient, ranked almost in the penultimate or second For-each Iterative entries performance is best, but cannot remove For-each iterative keys and values are no more than For-each iterative entries performance (about Fast 10%),

Recently made a technical blog site, organized a study of the Java process to do examples and small projects, are placed on the site to provide download, there are examples of beginners, there are Java Web examples, as well as my university during the graduation design source, can be downloaded.Address: micro-Child blog-java Novice

to be met, simplicity, and performance. There is often a mutual constraint between simplicity and performance. When implementing a synchronization strategy, be sure not to blindly sacrifice simplicity for performance (which could compromise security). When using a lock, you should be aware of the functionality implemented in the code block and whether it will take a long time to execute the code block. Whether you are performing a computationally intensive operation or performing

Today finally again picked up the Java Concurrency in practice, before the abuse of the pieces, before reading this book, there is a part of their own code I did not realize that the thread is not safe, but also really want to be bad to fill this knowledge.1.Java Monitor ModeMonitor mode is very simple, is to use a private object lock or built-in lock to ensure t

Friday free to do nothing, based on an analysis of the 12306 ticketing algorithm (Java version) theory, the Java coding practice for your readers reference (the following is a brief description of the relevant code) 1. Booking tool category 1.1 The ticket information of the initialization of a train compartment /** * Generate Ticket information * * @par