Java  5  &  6  Features  

Jussi  Pohjolainen  Tampere  University  of  Applied  Sciences  

Versions  and  Naming  

•  JDK  1.0  –  1996    •  JDK  1.1  –  1997  –  JDBC,  RMI,  ReflecQon..  •  J2SE  1.2  –  1998  –  Swing,  CollecQons..  •  J2SE  1.3  -­‐  2000  –  HotSpot  JVM..  •  J2SE  1.4  –  2002  –  assert,  NIO,  Web  start..  •  J2SE  5.0  (1.5)  –  2004  –  Generics,  Autoboxing..  •  Java  SE  6  (1.6)  –  2006  –  Rhino,  JDBC  4.0  …  •  Java  SE  7  (1.7)  –  2011  –  Small  language  changes,  API  Changes  

New  Features  •  Java  SE  5  –  Generics  –  Autoboxing  –  Improved  looping  syntax  –  AnnotaQons  –  …  

•  Java  SE  6  –  XML  Processing  and  Web  Services  –  ScripQng  –  JDBC  4.0  –  Desktop  APIs  –  …    

Generics   ArrayList list = new ArrayList();

list.add("a");

list.add("b");

list.add(new Integer(22));

Iterator i = list.iterator();

while(i.hasNext()) {

System.out.println((String) i.next());

}

Result  

Using  Generics   ArrayList<String> list = new ArrayList<String>();

list.add("a");

list.add("b");

list.add(new Integer(22));

Iterator<String> i = list.iterator();

while(i.hasNext()) {

System.out.println((String) i.next());

}

Result  

Enhanced  for  -­‐  loop   ArrayList<String> list = new ArrayList<String>();

list.add("a");

list.add("b");

list.add("c");

// Loop array or collection. Iteration used

// even without declaration! The list object

// must implement java.lang.Iterable interface

for(String alphabet : list) {

System.out.println(alphabet);

}

Java  1.4  import java.util.*; class Main { public static void main(String [] args) { // Does not work, 5 is not a Object type! someMethod(5); } public static void someMethod(Object a) { System.out.println(a.toString()); } }

Java  1.4:  SoluQon  import java.util.*; class Main { public static void main(String [] args) { Integer temp = new Integer(5); someMethod(temp); } public static void someMethod(Object a) { System.out.println(a.toString()); } }

Java  1.4:  Lot  of  Coding  

Integer a = new Integer(5);

Integer b = new Integer(6);

int aPrimitive = a.intValue();

Int bPrimitive = b.intValue();

Autoboxing  Comes  to  Rescue!  

class Main {

public static void main(String [] args) {

// Boxing

Integer a = 2;

// UnBoxing

int s = 5 + a;

}

}

Java  1.5  class Main { public static void main(String [] args) { // Works! someMethod(5); } public static void someMethod(Object a) { System.out.println(a.toString()); } }

Java  1.5  import java.util.*; class Main { public static void main(String [] args) { ArrayList<Integer> list = new ArrayList<Integer>(); list.add(5); list.add(new Integer(6)); list.add(7); for(int number : list) { System.out.println(number); } } }

Enum  

•  An  enum  type  is  a  type  whose  fields  consist  of  a  fixed  set  of  constants  

 enum Color {

WHITE, BLACK, RED, YELLOW, BLUE;

}

Usage  enum Color { WHITE, BLACK, RED, YELLOW, BLUE; } class Main { public static void main(String [] args) { System.out.println(Color.WHITE); Color c1 = Color.RED; System.out.println(c1); }

Enum  

•  Enum  declaraQon  defines  a  class!  •  Enum  can  include  methods  •  Enum  constants  are  final  staQc  •  Compiler  adds  special  methods  like  values  that  returns  an  array  containing  all  the  values  of  the  enum.  

•  Enum  class  extends  java.lang.enum  

Enum  enum Color { WHITE, BLACK, RED, YELLOW, BLUE; } class Main { public static void main(String [] args) { for (Color c : Color.values()) { System.out.println(c); } } }

StaQc  Import  (1/2)  

class Main {

public static void main(String [] args) {

int x = Integer.parseInt("55");

int y = Integer.parseInt("56");

int x = Integer.parseInt("57");

}

}

StaQc  Import  (2/2)  

import static java.lang.Integer.parseInt; class Main { public static void main(String [] args) { int x = parseInt("55"); int y = parseInt("56"); int z = parseInt("57"); } }

Metadata  

•  With  Java  5  it’s  possible  to  add  metadata  to  methods,  parameters,  fields,  variables..  

•  Metadata  is  given  by  using  annota,ons  •  Many  annota.ons  replace  what  would  otherwise  have  been  comments  in  code.  

•  Java  5  has  built-­‐in  annotaQons  

Override:  Does  not  Compile!  class Human { public void eat() { System.out.println("Eats food"); } } class Programmer extends Human { @Override public void eatSomeTypo() { System.out.println("Eats pizza"); } } class Main { public static void main(String [] args) { Programmer jack = new Programmer(); jack.eat(); } }

Other  AnnotaQons  used  By  Compiler  

•  @Depricated  –  Gives  warning  if  when  depricated  method  or  class  is  used  

•  @SuppressWarnings  –  Suppress  all  warnings  that  would  normally  generate  

System.out.format  import java.util.Date;

class Main {

public static void main(String [] args) {

Date d = new Date();

// Lot of format characters available!

System.out.format("Today is %TF", d);

}

}

Variable  Argument  List  class Main { public static void printGreeting(String... names) { for (String n : names) { System.out.println("Hello " + n + ". "); } } public static void main(String[] args) { String [] names = {"Jack", "Paul"}; printGreeting("Jack", "Paul"); printGreeting(names); } }

User  Input:  Scanner  

Scanner in = new Scanner(System.in);

int a = in.nextInt();

Java  6:  XML  &  Web  Services  

•  Easy  way  of  creaQng  Web  Services  •  Expose  web  service  with  a  simple  annotaQon      

Web  Service  package hello; import javax.jws.WebService; @WebService public class CircleFunctions { public double getArea(double r) {

return java.lang.Math.PI * (r * r); } public double getCircumference(double r) { return 2 * java.lang.Math.PI * r; } }

Server  import javax.xml.ws.Endpoint;

class Publish {

public static void main(String[] args) {

Endpoint.publish(

"http://localhost:8080/circlefunctions",

new CircleFunctions());

}

Generate  Stub  Files  

•  Generate  stub  files:  – wsgen  –cp  .  hello.CircleFuncQons  

Java  6:  Rhino  

•  Framework  to  connect  to  Java  programs  to  scripQng-­‐language  interpreters.  

•  Rhino  JS  Engine  comes  with  Java  6  •  To  ability  to  run  JS  from  Java  and  JS  from  command  line  

•  Rhino  is  wriken  in  Java  

Example  import javax.script.ScriptEngine; import javax.script.ScriptEngineManager; import javax.script.ScriptException; public class Main { public static void main(String[] args) { ScriptEngineManager mgr = new ScriptEngineManager(); ScriptEngine engine = mgr.getEngineByName("JavaScript"); // Now we have a script engine instance that // can execute some JavaScript try { engine.eval("print('Hello')"); } catch (ScriptException ex) { ex.printStackTrace(); } } }

Java  6:  GUI  

•  Faster  Splash  Screens  •  System  tray  support  •  Improved  Drag  and  Drop  •  Improved  Layout  •  WriQng  of  Gif  -­‐  files  

Java  6:  DB  Support  

•  Java  6  comes  with  preinstalled  relaQonal  database,  Oracle  release  of  Apache  Derby  Project  

•  Java  DB  is  installed  automaQcally  as  part  of  the  Java  SE  Development  Kit  (JDK).  

•  For  a  Java  DB  installaQon,  set  the  DERBY_HOME  environment  variable  

Java  7  

•  Using  Strings  in  switch  statements  •  Syntax  for  automaQc  cleaning  of  streams  •  Numeric  literals  with  underscores  •  OR  in  excepQon  catches