- Compiled and Interpreted – Usually a language either is compiled or is interpreted. However, Java is both complied and interpreted and has two – stage systems. First, Java compiler translates source code into what is known as byte code instructions. Byte codes are not machine instructions and therefore, in the second stage, Java interpreter generates machine code that can be directly executed by the machine that is running the Java program.
- Platform Independent and Portable – The most significant contribution of Java over the other languages is its portability. Java programs can be easily moved from one computer to another computer, anywhere and anytime. Changes and upgrades in the Operating System do not affect the programs written in Java. This is the reason why Java is popular in developing Internet applications where different kinds of system are connected worldwide. Java also ensures portability. Firstly, when the compiler generates byte codes, it can be implemented on any machine. Secondly, the size of the primitive data types is machine independent.
- Object – Oriented – Java is a true OOP. Almost everything in Java is Object. All program code and data reside within objects and classes. Java comes with an extensive set of classes, arranged in packages that we can use in our programs by inheritance. The object model in Java is simple and easy to extend.
- Robust and secure – Java is a robust language. It provides many safeguards to ensure reliable code. It has strict compile time and run time checking for data types. It is designed as garbage – collected language relieving the programmer virtually all memory management problems. Java also incorporates the concept of exception handling which captures series errors and eliminates any risk of crashing the system. Security becomes an important issue for a language that is used for programming on Internet. Threat of viruses and abuse of resources are everywhere. Java systems not only verify all memory access but also ensure that no viruses are communicated with an applet. The absence of pointers in Java ensures that programs cannot gain access to memory locations without proper authorization.
- Distributed – Java is designed as a distributed language for creating applications on networks. It has the ability to share both data and programs. Java applications can open and access remote objects on Internet as easily as they can do in a local system. This enables multiple programmers’ remote locations to collaborate and work together on a single project.
- Simple, Small and Familiar – Java is a small and simple language. Many features of C and C++ that are either redundant or sources of unreliable code are not part of Java. For example, Java does not use pointers, pre-processor header files, goto statement and many others. It also eliminates operator overloading and multiple inheritance. Familiarity is another striking feature of Java. To make a language look familiar to the existing programmers, it was modelled on C and C++ languages. Java uses many constructs of C and C++ and therefore, Java code looks like C++. In Fact, Java is a simplified version of C++.
- Multithreaded and Interactive – It means handling multiple tasks simultaneously. Java supports multithreaded programming. This means we need not wait for the application to finish one task before beginning another. This feature greatly improves the interactive performance of the applications. The Java runtime comes with the tools that support multi process synchronization and construct smoothly running interactive systems.
- High performance – Java performance is impressive for an interpreted language, mainly due to the use of intermediate byte code. According to Sun, Java speed is comparable to the native C/C++. Java architecture is also designed to reduce the overheads during runtime. Further, the incorporation of multithreading enhances the overall execution speed of Java programs.
- Dynamic and Extensible – Java is a dynamic language. Java is capable of dynamically linking in new class libraries, methods, and objects. Java can also determine the type of class through a query, making it possible to either dynamically link or abort the program, depending on the response. Java programs support functions written in other languages such as C and C++. These functions are known as native methods. This facility enables the programmers to use the efficient functions available in these languages. Native methods are linked dynamically at runtime.
- Ease of Development – Java 2 Standard Edition (J2SE) 5.0 supports features, such as Generics, Enhanced for loop, Autoboxing or unboxing, Typesafe Enums, Varage, Static import and Annotation. These features reduce the work of the programmer by shifting the responsibility of creating the reusable code to the compiler. The resulting source code\is free from the bugs because the errors made by the compiler are less when compared to those made by the programmers. Thus, each of the linguistic feature is designed to develop Java program in an easier way
- Scalability and Performance – J2SE 5.0 assures a significant increase in stability and performance by improving the start-up time and reducing the amount of memory used in Java 2 runtime environment. For example, the introduction of the class, data sharing in the Hotspot Java Virtual Machine (JVM) improves the start-up time by loading the core classes from the jar files into a shared archive. Memory utilization is reduced by sharing data in the shared archive among multiple JVM processes. In the earlier versions, the data was represented in each JVM instance.
- Monitoring and Manageability – Java supports a number of APIs, such as JVM Monitoring and Management API, Sun Management Platform Extension, Logging, Monitoring and Management Interface, and Java Management Extension (JMX) to monitor and manage Java applications. For example, Java provides JVM Monitoring and Management API to track the information at the application level and JVM level when deploying a large application. Java provides tools, such as jconsole, jps, jstat, and jstatd to make use of monitoring and management facilities. For example, GUI based tool called jconsole is used to monitor the JVM.
- Desktop Client – J2SE 5.0 provides enhanced features to meet the requirements and challenges of Java desktop users. It provides an improvised Swing look and feel the Ocean. This feature is mainly used for developing graphics applications that require OpenGL hardware acceleration.
- Java – The 2012 Review and Future Predictions (javacodegeeks.com)
- RubyFlux: a Ruby to Java compiler (github.com)
- Java’s Magic:The Byte-Code (technoleaf.wordpress.com)