Developed by Sun Microsystems (James Gosling) A general-purpose object-oriented language Based on C/C++ Designed for easy Web/Internet applications Widespread acceptance Simple fixes some clumsy features of C++ no pointers automatic garbage collection rich pre-defined class library Object oriented focus on the data (objects) and methods manipulating the data all functions are associated with objects almost all data types are objects (files, strings, etc.) potentially better code organization and reuse. | Lecture 1: Overview of Java What is java? Developed by Sun Microsystems (James Gosling) A general-purpose object-oriented language Based on C/C++ Designed for easy Web/Internet applications Widespread acceptance Java Features (1) Simple fixes some clumsy features of C++ no pointers automatic garbage collection rich pre-defined class library Object oriented focus on the data (objects) and methods manipulating the data all functions are associated with objects almost all data types are objects (files, strings, etc.) potentially better code organization and reuse Interpreted java compiler generate byte-codes, not native machine code the compiled byte-codes are platform-independent java byte codes are translated on the fly to machine readable instructions in runtime (Java Virtual Machine) Portable same application runs on all platforms the sizes of the primitive data types are always the same the libraries define portable interfaces Java Features (2) Java Features (3) Reliable extensive compile-time and runtime error checking no pointers but real arrays. Memory corruptions or unauthorized memory accesses are impossible automatic garbage collection tracks objects usage over time Secure usage in networked environments requires more security memory allocation model is a major defense access restrictions are forced (private, public) Java Features (4) Multithreaded multiple concurrent threads of executions can run simultaneously utilizes a sophisticated set of synchronization primitives (based on monitors and condition variables paradigm) to achieve this Dynamic java is designed to adapt to evolving environment libraries can freely add new methods and instance variables without any effect on their clients interfaces promote flexibility and reusability in code by specifying a set of methods an object can perform, but leaves open how these methods should be implemented can check the class type in runtime Java Disadvantages Slower than compiled language . | Lecture 1: Overview of Java What is java? Developed by Sun Microsystems (James Gosling) A general-purpose object-oriented language Based on C/C++ Designed for easy Web/Internet applications Widespread acceptance Java Features (1) Simple fixes some clumsy features of C++ no pointers automatic garbage collection rich pre-defined class library Object oriented focus on the data (objects) and methods manipulating the data all functions are associated with objects almost all data types are objects (files, strings, etc.) potentially better code organization and reuse Interpreted java compiler generate byte-codes, not native machine code the compiled byte-codes are platform-independent java byte codes are translated on the fly to machine readable instructions in runtime (Java Virtual Machine) Portable same application runs on all platforms the sizes of the primitive data types are always the same the libraries define portable interfaces Java Features (2) Java Features (3) Reliable
