The Java programming language was developed by a small team of engineers, known as the Green Team, who initiated the language in Originally called OAK, the Java language was designed for handheld devices and set-top boxes. Oak was unsuccessful and in Sun changed the name to Java and modified the language to take advantage of the burgeoning World Wide Web.
Each package contains a set of related interfacesclasses, and exceptions. Refer to the separate platforms for a description of the packages available. Execution System Main articles: Java software platform and Java virtual machine One design goal of Java is portability, which means that programs written for the Java platform must run similarly on any combination of hardware and operating system with adequate runtime support.
This is achieved by compiling the Java language code to an intermediate representation called Java bytecodeinstead of directly to architecture-specific machine code. Java bytecode instructions are analogous to machine code, but they are intended to be executed by a virtual machine VM written specifically for the host hardware.
End users commonly use a Java Runtime Environment JRE installed on their own machine for standalone Java applications, or in a web browser for Java applets. Standard libraries provide a generic way to access host-specific features such as graphics, threadingand networking. The use of universal bytecode makes porting simple.
However, the overhead of interpreting bytecode into machine instructions made interpreted programs almost always run more slowly than native executables. Just-in-time JIT compilers that compile bytecodes to machine code during runtime were introduced from an early stage. Non-JVM Some platforms offer direct hardware support for Java; there are microcontrollers that can run Java bytecode in hardware instead of a software Java virtual machine,  and some ARM based processors could have hardware support for executing Java bytecode through their Jazelle option, though support has mostly been dropped in current implementations of ARM.
Automatic memory management Java uses an automatic garbage collector to manage memory in the object lifecycle. The programmer determines when objects are created, and the Java runtime is responsible for recovering the memory once objects are no longer in use. Once no references to an object remain, the unreachable memory becomes eligible to be freed automatically by the garbage collector.
If methods for a nonexistent object are called, a "null pointer exception" is thrown. In some languages, memory for the creation of objects is implicitly allocated on the stack or explicitly allocated and deallocated from the heap. In the latter case, the responsibility of managing memory resides with the programmer.
If the program does not deallocate an object, a memory leak occurs. If the program attempts to access or deallocate memory that has already been deallocated, the result is undefined and difficult to predict, and the program is likely to become unstable or crash. This can be partially remedied by the use of smart pointersbut these add overhead and complexity.
Note that garbage collection does not prevent "logical" memory leaks, i. Garbage collection may happen at any time. Ideally, it will occur when a program is idle. It is guaranteed to be triggered if there is insufficient free memory on the heap to allocate a new object; this can cause a program to stall momentarily.
Explicit memory management is not possible in Java. This allows the garbage collector to relocate referenced objects and ensures type safety and security. Java contains multiple types of garbage collectors. By default, HotSpot uses the parallel scavenge garbage collector.
Java syntax Dependency graph of the Java Core classes created with jdeps and Gephi. The most frequently used classes Object and String appear in the centre of the diagram.
There are three different styles of comments: The Javadoc style of commenting allows the user to run the Javadoc executable to create documentation for the program and can be read by some integrated development environments IDEs such as Eclipse to allow developers to access documentation within the IDE.
It must first be compiled into bytecode, using a Java compilerproducing a file named HelloWorldApp.Java is a general-purpose computer-programming language that is concurrent, class-based, object-oriented, and specifically designed to have as few implementation dependencies as possible.
It is intended to let application developers "write once, run anywhere" (WORA), meaning that compiled Java code can run on all platforms that support Java without the need for urbanagricultureinitiative.comed by: James Gosling.
If you are new to programming in the Java language, have some experience with other languages, and are familiar with things like displaying text or graphics or performing simple calculations, this tutorial could be for you. DESCRIPTION. The javac tool reads class and interface definitions, written in the Java programming language, and compiles them into bytecode class files.
It can also process annotations in Java source files and classes. There are two ways to . The word "Java", alone, usually refers to Java programming language that was designed for use with the Java platform. Programming languages are typically outside of the scope of the phrase "platform", although the Java programming language was listed as a core part of the Java platform before Java 7.
Java Programmer Job Description Java programmers are specialists in working with software applications using the Java programming language.
Java is a programming language that allows interactivity on websites and desktop software applications. Java is a widely used programming language expressly designed for use in the distributed environment of the internet.
It is the most popular programming language for Android smartphone applications and is among the most favored for edge device and internet of things development.