what is rule engine in java

The Equals and Hashcode methods in Java are in object objects, so each object has these two methods, and most of the time we need to override both methods in order to implement the specific requirementsThe Equals and Hashcode methods are commonly used in the same class for comparisons, especially when comparing elements in a set collection The Equals method returns true for two objects, hashcode must be the same Hashcode the same two objects,

]; Boolean oldalthashing = usealthashing; Usealthashing |= sun.misc.VM.isBooted () (newcapacity >= holder.alternative_hashing_threshold); Boolean rehash = oldalthashing ^ usealthashing; Transfer (newtable, rehash);//Transfer method table = newtable; threshold = (int) math.min (newcapacity * loadfactor, maximum_capacity + 1); }You can see that the maximum value of the threshold threshold is i

compilation type of the object is changed to the object type, but its run-time type is still its own type.2. As a result, it is necessary to//1 the collection element into the specific target type, and the "java.lang.ClassCastException" exception can easily occur.So is there any way that the collection can remember th

command manual for the command meaning): C:/dumps/myappC:/dumps/myappC:/dumps/myapp.dmpExecuting the above results in a DMP file.3. How to analyze dump filesThe dump file can also be analyzed via WinDbg, with the following steps: Open WinDbg, open File->sybolm File path, specify the path of the. PDB generated when publishing exe. Open File->open Crash Dump, open a. dmp file. Use the WinDbg command to parse a bug, such as (you can query the WinDbg command manual for the mea

Because of business needs, data communication is required between different servers on multiple platforms (Java amp; PHP) and encrypted communication is required. There is no experience in this field. Is there any solution to achieve this? This

To say super is to say this first.2. Can be used inside a non-static member of a class to represent the current object. At this point, this is a final normal variable, which has a static type, which is the class C itself; it has a dynamic type, which is the type of the current object. You can call member functions on i

Serialization: The ability to represent an object in a binary representation.Like my first byte denotes what attribute noun, the second byte represents what property value, the first few fields represent a few attributes, and so on.And this binary can be written to the hard disk or transmitted over the network without destroying his structure. A generic remote method call

though Thread2 calls the sleep method below for 10 milliseconds, Thread1 still does not execute because THREAD2 does not release the lock, so Thread1 cannot get the lock. */system.out.println ("Thread2 is sleeping ten millisecond ..."); try {thread.sleep (10);} catch (Interruptedexception e) {e.printstacktrace ();} System.out.println ("Thread2 is going on ..."); System.out.println ("Thread2

, uses the test environment The goal is, the test, does not affect the on-line item the normal use, and so on test completes, then on production environment. ） ----------------------------------------------------------------------- General company how to build Java development, testing, production environment The most used code hosting is SVN, local development

Recently, when I read the Jackson source, I found that there was a code return type written by Question: What are the differences between the declarations of the following 2 methods Public object DoSomething (Object obj) {...} public Answer:Single from the above 2 method declarations-no difference. Either t or obj, you can only invoke parameters and return values of type object.But based on the 2 methods above, if you have a class that uses generics:

Serialization is the process of writing the state of an object to a byte stream, it executes Rmi,rmi allows Java objects on one machine to invoke Java object methods on different machines, and objects can be supplied as parameters to that remote method, the transmitter serializes the object and transmits it, and the receiver performs deserialization. A diagram of

class, unnecessarily increasing the compiler resolution cost, and accessing it directly with the class name. Ali as far as possible do not define variables in the interface, if you must define variables, it must be related to the interface method. Don't show magic numbers in the program. Summary : The constants in a Java project define a final class and have a private constructor method, the demo code is a

}); AExecutors.newsinglethreadexecutor (). Execute (Newrunable ( -{ Public voidrun () { - } the});There are two ways to implement it, usingNew Thread ()AndNew Thread (runnable)form, the first kind of direct callThreadOfRunmethod, so we tend to useThreadSubclass, which isNew Subthread ()。 The second kind of tuneUseRunnableOfRunMethod.There are two ways to implement this, namely, inheritanceThreadClasses and implementationsRunnableInterfaceUseSynchronizedKeyword Retouching synchronization met

public static void Printcoll (ArraylistIteratorwhile (It.hasnext ()){System.out.println (It.next (). toString ());}？ and T both represent the type of uncertainty, but if it is T, then the function can operate on t, such as while it can be written like thisT t = It.next ();System.out.println (t); T custom generics and? Wildcard generics 1. There is only one place in the entire class that uses generics, and

Java is an object-oriented programming language, everything is an object, but for the convenience of programming or introduce basic data types, in order to be able to use these basic data types as Object operations, Java for each basic data type has introduced the corresponding wrapper type (wrapper class), int's wrapp

An object-serialized interface in which the object of a class is serializable only if it implements the serializable interface. So if you want to serialize objects of some classes, these classes must implement the Serializable interface. In fact, serializable is an empty interface with no specific content, and its purpose is simply to identify the object of a cla

Java Beans are reusable components. Generally, Because Java Beans are created by containers (such as Tomcat), Java Beans should have a no-argument constructor, generally, Java Bean must implement the serializable interface to realize bean persistence. Enterprise Java Bean d

What is the adaptation class for java-7.6 adaptation design patterns? Or the adaptation interface? In this chapter, let's discuss the adaptation issue? To put it bluntly, you can use any object to call a method, and this object only needs to comply with certain protocols. The implementation of this protocol has two methods: inheritance and interface, but interfac

Final is a modifier that can be used to modify variables, methods, and classes. When modifying a variable. Represents a variable that cannot be changed, that is, a constant. Constants need to be assigned at the time of definition or assigned by constructors, and they can only be selected; When the method is modified, the method can only be called, cannot be overr

Because of the test environment under Linux, the sharing mechanism of variables in Linux environment: About Export1. The system environment variables in a shell are copied to the sub shell (with the variables defined by export).2. The system environment variable in a shell is valid only for the shell or its child shell, and the variable disappears at the end of the shell (and cannot be returned to the parent shell).3. A variable that