JDK 1.7 : Useful Features

 Useful Features in JDK 1.7

Following are the features that are very useful JDK 1.7

     1.       Strings in switch Statements   : We can start using Strings in switch case statements:

String option;

switch(option)

{

        case “start”:

                        System.out.println(“Starting the process”);

                        …….

                        break;

        case “pause”:

                        System.out.println(“Pausing the process”);

                        break;

        case “stop”:

                        System.out.println(“Stopping the process”);

                        break;

        default:

                        System.out.println(“continue”);

                        break;

}

     2.       Catching Multiple Exception Types and Rethrowing Exceptions with Improved Type Checking : We would have been using multiple catch blocks doing the same thing. Below is an example where this can be used

Pre JDK 1.7

JDK 1.7

try {                 …. }catch(FileNotFoundException fe) {    log.error(“---EXCEPTION occurred with file handling-- ”+ fe.getMessage());    throw new CustomException(fe); }catch(IOException ie) {    log.error(“---EXCEPTION occurred with file handling-- ”+ ie.getMessage());    throw new CustomException(Ie); }catch(Exception e) {    log.error(“---EXCEPTION occurred with file handling-- ”+ e.getMessage());    throw new CustomException(e); }

try { }catch(FileNotFoundException |  IOException | Exception e) {     log.error(“---EXCEPTION occurred with file handling-- ”+ e.getMessage());     throw new CustomException(e); }

3.  The try-with-resources Statement  :  We can open Autoclosable  resources like Streams, JDBC connection, Statements, Resultset within the try.  The resources will be automatically closed when the try ends.

Pre JDK 1.7	JDK 1.7 (resources are auto-closed after the try statement)
BufferedReader breader = new BufferedReader(new FileReader(path)); FileOutputStream fs = new FileOutputStream(new File (…));   try {      …        …   } finally {     if (breader != null)          breader.close();     if (os != null)          os.close();   }	try(BufferedReader breader = new BufferedReader(new FileReader(path));      FileOutputStream fs = new FileOutputStream(new File (…))   ){       ………………….   }catch(..){      ….   }

   4. Automatic Type inference : Easy Type declaration. This will not work when declaring Generics with wildcard.

Pre JDK 1.7	JDK 1.7 :  Easy declaration with “diamond Operator”
List<String> listNames = new ArrayList<String>(); Map<String, Integer> mapStrNumbers = new HashMap<String, Integer>();	List<String> listNames = new ArrayList<>(); Map<String, Integer> mapStrNumbers = new HashMap<>();

References: http://www.oracle.com/technetwork/java/javase/jdk7-relnotes-418459.html