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Weak Reference
In computer programming, a weak reference is a reference that does not protect the referenced object from collection by a garbage collector, unlike a strong reference. An object referenced ''only'' by weak references – meaning "every chain of references that reaches the object includes at least one weak reference as a link" – is considered '' weakly reachable,'' and can be treated as unreachable and so may be collected at any time. Some garbage-collected languages feature or support various levels of weak references, such as C#, Lua, Java, Lisp, OCaml, MATLAB, Perl, Python and PHP since the version 7.4. Uses Weak references have a number of common uses. When using reference counting garbage collection, weak references can break reference cycles, by using a weak reference for a link in the cycle. When one has an associative array (mapping, hash map) whose keys are (references to) objects, for example to hold auxiliary data about objects, using weak references for the keys a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Programming
Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of procedures, by writing source code, code in one or more programming languages. Programmers typically use high-level programming languages that are more easily intelligible to humans than machine code, which is directly executed by the central processing unit. Proficient programming usually requires expertise in several different subjects, including knowledge of the Domain (software engineering), application domain, details of programming languages and generic code library (computing), libraries, specialized algorithms, and Logic#Formal logic, formal logic. Auxiliary tasks accompanying and related to programming include Requirements analysis, analyzing requirements, Software testing, testing, debugging (investigating and fixing problems), imple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observer Pattern
In software design and software engineering, the observer pattern is a software design pattern in which an object, called the ''subject'' (also known as ''event source'' or ''event stream''), maintains a list of its dependents, called observers (also known as ''event sinks''), and automatically notifies them of any state (computer science), state changes, typically by calling one of their method (computer science), methods. The subject knows its observers through a standardized interface and manages the subscription list directly. This pattern creates a one-to-many dependency where multiple observers can listen to a single subject, but the coupling is typically synchronous and direct—the subject calls observer methods when changes occur, though asynchronous implementations using event queues are possible. Unlike the publish-subscribe pattern, there is no intermediary broker; the subject and observers have direct references to each other. It is commonly used to implement event ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Platform, Standard Edition
Java Platform, Standard Edition (Java SE) is a computing platform for development and deployment of porting, portable code for desktop computer, desktop and server (computing), server environments. Java SE was formerly known as Java 2 Platform, Standard Edition (J2SE). The platform uses the Java (programming language), Java programming language and is part of the Java (software platform), Java software-platform family. Java SE defines a range of general-purpose APIs—such as List of Java APIs, Java APIs for the Java Class Library—and also includes the Java Language Specification and the Java Virtual Machine Specification. OpenJDK is the official reference implementation since version 7. Nomenclature, standards and specifications The platform was known as ''Java 2 Platform, Standard Edition'' or ''J2SE'' from version 1.2, until the name was changed to ''Java Platform, Standard Edition'' or ''Java SE'' in version 1.5. The "SE" is used to distinguish the base platform from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Package
A Java package organizes Java classes into namespaces, providing a unique namespace for each type it contains. Classes in the same package can access each other's package-private and protected members. In general, a package can contain the following kinds of types: classes, interfaces, enumerations, records and annotation An annotation is extra information associated with a particular point in a document or other piece of information. It can be a note that includes a comment or explanation. Annotations are sometimes presented Marginalia, in the margin of book page ... types. A package allows a developer to group classes (and interfaces) together. These classes will all be related in some way – they might all have to do with a specific application or perform a specific set of tasks. Programmers also typically use packages to organize classes belonging to the same category or providing similar functionality. Using packages In a Java source file, the package that this file' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phantom Reference
A phantom reference is a kind of reference in Java (programming language), Java, where the memory can be reclaimed. The phantom reference is one of the strengths or levels of 'non strong reference, strong' reference defined in the Java programming language; the others being weak reference, weak and soft reference, soft. Phantom reference are the weakest level of reference in Java; in order from strongest to weakest, they are: strong, soft, weak, ''phantom.'' An object is phantomly referenced after it has been finalizer, finalized. In Java 8 and earlier versions, the reference needs to be cleared before the memory for a finalized referent can be reclaimed. A change in Java 9 will allow memory from a finalized referent to be reclaimable immediately. Use Phantom references are of limited use, primarily narrow technical uses. First, it can be used instead of a finalize method, guaranteeing that the object is not resurrected during finalization. This allows the object to be garbage co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soft Reference
A soft reference is a reference that is garbage-collected less aggressively. The soft reference is one of the strengths or levels of 'non strong' reference defined in the Java programming language, the others being weak and phantom. In order from strongest to weakest, they are: strong, ''soft,'' weak, phantom. Soft references behave almost identically to weak references. Soft and weak references provide two quasi-priorities for non-strongly referenced objects: the garbage collector will always collect weakly referenced objects, but will only collect softly referenced objects when its algorithms decide that memory is low enough to warrant it. Soft references may be used, for example, to write a free memory sensitive cache such that cached objects are kept until there is not enough heap space. In some cases weakly referenced objects may be reclaimed too quickly to make such a cache useful. See also * Circular reference * Phantom reference * Weak reference In computer programming, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boost (C++ Libraries)
Boost, boosted or boosting may refer to: Science, technology and mathematics * Boost, positive manifold pressure in Turbocharger, turbocharged engines * Boost (C++ libraries), a set of free peer-reviewed portable C++ libraries * Boost (material), a material branded and used by Adidas in the midsoles of shoes. * Boost, a loose term for turbo or supercharger * Boost converter, an electrical circuit variation of a DC to DC converter, which increases (boosts) the voltage * Boosted fission weapon, a type of nuclear bomb that uses a small amount of fusion fuel to increase the rate, and thus yield, of a fission reaction * Boosting (behavioral science), a technique to improve human decisions * Boosting (machine learning), a supervised learning algorithm * Intel Turbo Boost, a technology that enables a processor to run above its base operating frequency * Jump start (vehicle), to start a vehicle * Lorentz boost, a type of Lorentz transformation Arts, entertainment, and media Fictional ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smart Pointer
In computer science, a smart pointer is an abstract data type that simulates a pointer while providing added features, such as automatic memory management or bounds checking. Such features are intended to reduce bugs caused by the misuse of pointers, while retaining efficiency. Smart pointers typically keep track of the memory they point to, and may also be used to manage other resources, such as network connections and file handles. Smart pointers were first popularized in the programming language C++ during the first half of the 1990s as rebuttal to criticisms of C++'s lack of automatic garbage collection. Pointer misuse can be a major source of bugs. Smart pointers prevent most situations of memory leaks by making the memory deallocation automatic. More generally, they make object destruction automatic: an object controlled by a smart pointer is automatically destroyed ( finalized and then deallocated) when the last (or only) owner of an object is destroyed, for example ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C++11
C++11 is a version of a joint technical standard, ISO/IEC 14882, by the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC), for the C++ programming language. C++11 replaced the prior version of the C++ standard, named C++03, and was later replaced by C++14. The name follows the tradition of naming language versions by the publication year of the specification, though it was formerly named ''C++0x'' because it was expected to be published before 2010. Although one of the design goals was to prefer changes to the libraries over changes to the core language, C++11 does make several additions to the core language. Areas of the core language that were significantly improved include multithreading support, generic programming support, uniform initialization, and performance. Significant changes were also made to the C++ Standard Library, incorporating most of the C++ Technical Report 1 (TR1) libraries, except the library ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cocoa (API)
Cocoa is Apple's native object-oriented application programming interface (API) for its desktop operating system macOS. Cocoa consists of the Foundation Kit, Application Kit, and Core Data frameworks, as included by the Cocoa.h header file, and the libraries and frameworks included by those, such as the C standard library and the Objective-C runtime.Mac Technology Overview: OS X Frameworks Developer.apple.com. Retrieved on September 18, 2013. Cocoa applications are typically developed using the development tools provided by Apple, specifically Xcode (formerly [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Document Object Model
The Document Object Model (DOM) is a cros s-platform and language-independent API that treats an HTML or XML document as a tree structure wherein each node is an object representing a part of the document. The DOM represents a document with a logical tree. Each branch of the tree ends in a node, and each node contains objects. DOM methods allow programmatic access to the tree; with them one can change the structure, style or content of a document. Nodes can have event handlers (also known as event listeners) attached to them. Once an event is triggered, the event handlers get executed. The principal standardization of the DOM was handled by the World Wide Web Consortium (W3C), which last developed a recommendation in 2004. WHATWG took over the development of the standard, publishing it as a living document. The W3C now publishes stable snapshots of the WHATWG standard. In HTML DOM (Document Object Model), every element is a node: * A document is a document node. * All HTM ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory Leak
In computer science, a memory leak is a type of resource leak that occurs when a computer program incorrectly manages memory allocations in a way that memory which is no longer needed is not released. A memory leak may also happen when an object is stored in memory but cannot be accessed by the running code (i.e. unreachable memory). A memory leak has symptoms similar to a number of other problems and generally can only be diagnosed by a programmer with access to the program's source code. A related concept is the "space leak", which is when a program consumes excessive memory but does eventually release it. Because they can exhaust available system memory as an application runs, memory leaks are often the cause of or a contributing factor to software aging. Effects Minor leaks If a program has a memory leak and its memory usage is steadily increasing, there will not usually be an immediate symptom. In modern operating systems, normal memory used by an application is releas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
