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Phantom Reference
A phantom reference is a kind of reference in Java, where the memory can be reclaimed. The phantom reference is one of the strengths or levels of 'non strong' reference defined in the Java programming language; the others being weak and 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 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 collected in a single cycle, rather than needing to wait for a second GC cycle to ensure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java (programming Language)
Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It is a general-purpose programming language intended to let programmers ''write once, run anywhere'' ( WORA), meaning that compiled Java code can run on all platforms that support Java without the need to recompile. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of the underlying computer architecture. The syntax of Java is similar to C and C++, but has fewer low-level facilities than either of them. The Java runtime provides dynamic capabilities (such as reflection and runtime code modification) that are typically not available in traditional compiled languages. , Java was one of the most popular programming languages in use according to GitHub, particularly for client–server web applications, with a reported 9 million developers. Java was originally developed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strong 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#, Java, Lisp, OCaml, 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 avoids keeping the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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#, Java, Lisp, OCaml, 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 avoids keeping the ... [...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] |
Finalizer
In computer science, a finalizer or finalize method is a special method that performs finalization, generally some form of cleanup. A finalizer is executed during object destruction, prior to the object being deallocated, and is complementary to an initializer, which is executed during object creation, following allocation. Finalizers are strongly discouraged by some, due to difficulty in proper use and the complexity they add, and alternatives are suggested instead, mainly the dispose pattern (see problems with finalizers). The term ''finalizer'' is mostly used in object-oriented and functional programming languages that use garbage collection, of which the archetype is Smalltalk. This is contrasted with a '' destructor'', which is a method called for finalization in languages with deterministic object lifetimes, archetypically C++. These are generally exclusive: a language will have either finalizers (if automatically garbage collected) or destructors (if manually memory manage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ephemeron
An ephemeron is a data structure that solves two related problems in garbage collected systems. On the one hand, an ephemeron provides a notification when some object is about to be collected. On the other hand, an ephemeron allows data to be associated with some object ''without'' creating a reference to that object that will prevent the object from being collected. An ephemeron is a key-value pair, where the key is the object that the ephemeron guards, notifying the system when that object is collectable, and the value can be any data associated with the object such as a property list, and which may be empty. Since the elements of the property list may refer back to the key, they may prevent collection of that key. But the ephemeron is treated specially by the garbage collector. The value field is not traced until the key is found to be reachable from the system roots other than through ephemeron keys. The set of ephemerons whose keys are only reachable from ephemeron key ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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#, Java, Lisp, OCaml, 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 avoids keeping the ... [...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] |
Circular Reference
A circular reference is a series of references where the last object references the first, resulting in a closed loop. In language A circular reference is not to be confused with the logical fallacy of a circular argument. Although a circular reference will often be unhelpful and reveal no information, such as two entries in a book index referring to each other, it is not necessarily so that a circular reference is of no use. Dictionaries, for instance, must always ultimately be a circular reference since all words in a dictionary are defined in terms of other words, but a dictionary nevertheless remains a useful reference. Sentences containing circular references can still be meaningful: :''Her brother gave her a kitten; his sister thanked him for it.'' is circular, but not without meaning. Indeed, it can be argued that self-reference is a necessary consequence of Aristotle's Law of non-contradiction, a fundamental philosophical axiom. In this view, without self-referen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Programming Constructs
Program, programme, programmer, or programming may refer to: Business and management * Program management, the process of managing several related projects * Time management * Program, a part of planning Arts and entertainment Audio * Programming (music), generating music electronically * Radio programming, act of scheduling content for radio * Synthesizer programmer, a person who develops the instrumentation for a piece of music Video or television * Broadcast programming, scheduling content for television * Program music, a type of art music that attempts to render musically an extra-musical narrative * Synthesizer patch or program, a synthesizer setting stored in memory * "Program", an instrumental song by Linkin Park from '' LP Underground Eleven'' * Programmer, a film on the lower half of a double feature bill; see B-movie Science and technology * Computer program, a set of instructions that describes how to perform a specific task to a computer. * Computer programmi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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