Java: An Overview John R Durrett Texas Tech University

Object Oriented Programming Vocabulary of OOP l Class - “Cookie cutter” l Object - “Cookie” l 3 Pillars of OO Wisdom l #1 Encapsulation

Object Oriented Programming l # 2 Polymorphism l # 3 Inheritance

Java The History of Java l Oak –Green Project –small appliance user interface l To Java in early 1995 l Distributed programming l Well accepted by developers l Acceptance by users is unclear

Java Strengths l Architecturally neutral –“comterpreted” –standardized APIs l Multiple execution paths l Managed memory system l Easy –single inheritance –memory management –dynamic linking –no pointers

Java Security l Program (bytecode) verification l No Overflows l Variables by name not memory l Applets –no file i/o –limited network connectivity –no external application calls –signed jar files l Applications

Java Java vs. C++ l No structs or enums l Easy to use exceptions l No functions, all object oriented l No multiple inheritance l No operator overloading l No direct memory pointers l No automatic type conversions l No preprocessor l Dynamic linking

Java Weaknesses l Java is slow –cost of interpreted language –cost of multi-threading –JIT compilers, Java chip –Native compilers l Lack of dynamic mobility –Mobility continuum –Object state –Tcl, Telescript l No uniform comm. model l lack of standardized JVM

Java Tools and APIs l First generation tools –JDK, Symantec Café l Second generation –J++, Visual J++ –Visual Café 2.0 –Visual Age for Java l Third party packages l Third party java beans

Java: Fad or Fundamental? Is it safe to bet your job on java? l William Blundon –“The Truth about Java,” Internet World, V7N12, Dec 1996 –Director OMG l Good platform for building Client Software l Easy to use and learn l High Quality code

Java: Fad or Fundamental? Promises for the future? l Good for Server Applications –database access (jdbc) –I/O –execution speed –three tier distributed systems l Secure l Write once & port anywhere l Portable object components –Java Beans