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Why use Java?

Why use Java?. Chris Loftus cwl@aber.ac.uk. It’s easy to knock the top dog. Maturity Lots of support documentation Huge standard libraries (3777 classes in Java 6) Big community Etc But is it a super-tanker, and does that matter?. My general view.

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Why use Java?

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  1. Why use Java? Chris Loftus cwl@aber.ac.uk CS25510: Why use Java?

  2. It’s easy to knock the top dog • Maturity • Lots of support documentation • Huge standard libraries (3777 classes in Java 6) • Big community • Etc • But is it a super-tanker, and does that matter? CS25510: Why use Java?

  3. CS25510: Why use Java?

  4. My general view • Don’t be dogmatic; use the right language for the right job... • Don’t slavishly follow the latest trends • Dynamically typed script languages are also not that “silver bullet” • Sometimes there are several equally valid choices... CS25510: Why use Java?

  5. Promises of Java: WORA • An aim of Java in 96 was ability to program small devices, e.g. set-top boxes... • Write Once Run Anywhere is important • There are JVMs for all computer platforms • Symbian OS 47% of smart mobile phones (2008), includes Java ME... • Amazon Kindle, Blu-ray Disc, EA Mobile, etc...(http://www.java.com/en/java_in_action) • Large usage on server-side: e.g. eBay uses Java, Infosys Technologies, parts of Amazon (Jboss, servlets), parts of Google, Twitter (Scala on top of JVM for backend),... CS25510: Why use Java?

  6. Promises of Java: WORA: Issues • GUIs: Swing pure Java components give WORA, but performance issues and pluggable OS-specific LAFs not accurate... • Initially Java 1.1 Green Threads, now native used... • Performance issues: cross platform means use of interpreters and/or JIT compilers...(more on this later) • Not the only WORA kid on the block: those script languages and Mono .NET IL...

  7. Promises of Java: Network/Web programming • From the start: sockets, applets, HTTP support, RMI (97), servlets (97), CORBA support (98), JSP (99), JMS (2001), etc • Web service support: • JAX-WS etc for W3C SOAP/WSDL style... • JAX-RS for REST style... • Web programming support: • Struts, JSF (with Ajax), Java EE 5, Spring, Google Web Toolkit, JavaFX ...

  8. Promises of Java: Network/Web programming: Issues • All programming platforms now support networking • However, Java maturity in this area • Some platforms (e.g. Ruby-on-Rails) support web development more succinctly... • JavaFX is commonly believed to be too late as compared with Adobe Flex/AIR and Silverlight... • EJB and J2EE bloat-ware, the steep learning curve, and the influence of affluence...

  9. Promises of Java: Security • Networking requires security: • Java sandbox for applets... • Java Security Model... • Java Cryptography Architecture/Extension... • Java Authorization and Authentication Service... • Support for web service security (e.g. message-level encryption, in-progress as part of JAX-WS) • More comprehensive support than most platforms... CS25510: Why use Java?

  10. Promises of Java: Type-safe • Strong typing that is statically checked (at compile time) long v1 = 10.2; Object e = new Employee(); Employee e1 = e; • Strong typing that is dynamically checked... • Array index bounds checking... • No pointer arithmetic... • Consistent handling of floating point types... • Garbage collection rather than dealloc (memory management issue)... • Removes a class of runtime faults but performance and flexibility issues...

  11. Criticisms: Performance • Java’s had this poor performance tag for some time, is it still justified? • The HelloWorld comparison of Java and C is a little misleading: • A large JVM must be loaded and initialised... • For short-lived programs this might be an issue... • What do the benchmarks show us?... CS25510: Why use Java?

  12. See “The Computer Language Benchmarks Game” http://shootout.alioth.debian.org/

  13. CS25510: Why use Java?

  14. CS25510: Why use Java?

  15. Why performance worse than C/C++? • Load-time bytecode verification, array bounds checking, floating point simulation, garbage collection… • Loading the large JVM • Big start-up hit… • Big memory footprint… • Initially bytecode interpretation, JIT (1998), and then HotSpot (2000) • Adaptive compiler: initially interpreted but hotspots are compiled to native…

  16. Criticisms: Java is simply not fun • Lack of: • Default parameter values, operator overloading, closures, pure object orientation, string cases in switch statements, meta-programming support, convention over configuration... • And: • Boiler-plate code, checked exceptions... CS25510: Why use Java?

  17. HelloWorld in Java and Groovy public class HelloJava { public static void main(String [] args){ if (args.length > 0) System.out.format("Hello %s", args[0]); else System.out.print("Hello"); } } if (args) println "Hello ${args[0]}" else println "Hello" CS25510: Why use Java?

  18. Java is a super-tanker but I don’t think it matters • Criticised by many developers as not including features discussed earlier, and slow to add new features... • But many big projects want API stability, large mature reusable code libraries, proven technology, type safety, good security, and sufficient performance... • eBay replaced C++ with Java in 2002, citing Java’s good engineering support for their 1500+ developers • However Amazon use C++ for compute intensive work • And if you want to use those fun languages and have many of Java’s benefits why not use Scala, Groovy or Jruby?

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