Java 7 workshop

Java 7
Anything new under the Sun?

Versions
JDK 1.0 Jan, 1996
JDK 1.1 Feb, 1997
J2SE 1.2 Dec, 1998
J2SE 1.3 May, 2000
J2SE 1.4 Feb, 2002
J2SE 5.0 Sep, 2004
Java SE 6 Dec, 2006
Java SE 7 Jul, 2011

Plans
Plan A

JDK 7
As currently planned

Mid 2012

Plans
Plan A Plan B

JDK7 JDK8
JDK 7 minus Lambda,
Lambda, Jigsaw,
As currently planned Jigsaw, and part of
and rest of Coin
Coin

Mid 2012 Mid 2011 End 2012

Platform Features
API Features
Language Features

Dynamic Language
Support
JVM has no support for dynamic
languages:
• Existing JVM instruction set is
statically typed
• Limited support for dynamically
modifying existing classes and
methods

Dynamic Language
Support
Java 7 adds:
• a new invokedynamic instruction at the
JVM level
• ability to change classes and
methods at runtime dynamically in a
production environment.

Other Platform
Features

• JVM performance enhancements
• Upgrade class-loader architecture
• Garbage-First Collector
• New JavaDoc layout

NIO.2

• The FileVisitor API
• Directory watching
• File attributes
• Custom ﬁlesystem providers (ZIP)

Other API Features
• Updated XML stacks
• JDBC 4.1
• MethodHandles
• Unicode 6.0 and Locale enhancements
• Elliptic-curve cryptography
• Enhanced MBeans

Strings in switch
String line = in.readLine();

switch (line) {
case "hello":
   System.out.println("hello world!");
    return;
  case "cafe":
   System.out.println("cafebabe!");
    return;
  default:
   System.out.println("wrong...");
}

Literals

int binary = 0b1001_0000_1111_0010;
System.out.println(binary);
System.out.println(Integer.toBinaryString(binary));

int readableMillion = 1_000_000;
System.out.println(readableMillion);

int readableBillion = 1_000_000_000;
System.out.println(readableBillion);

Multi-catch
/* Java 6 and older */
} catch (IOException e) {
logger.log(e);
throw e;
} catch (SQLException e) {
logger.log(e);
throw e;
}

/* Java 7 */
} catch (IOException | SQLException e) {
logger.log(e);
throw e;
}

Precise rethrow
public void preciseRethrow() throws IOException {
    try {
        new SimpleDateFormat("yyyyMMdd").parse("foo");
        new FileReader("file.txt").read();
    } catch(ParseException e) {
        System.out.println(e.getMessage());
    } catch(Exception e) {
        System.out.println(e.getMessage());
        throw e;
    }
}

“Diamond”
/* Java 5 & 6 */
Map<String, List<String>> myMap = new HashMap<String,
List<String>>();

/* Java 7 */
Map<String, List<String>> myMap = new HashMap<>();

/* Be warned, the compiler still generates an unchecked
conversion warning! */
Map<String, List<String>> myMap = new HashMap();

Try-with-resources

File file = new File("input.txt");

try (InputStream is = new FileInputStream(file)) {
// do something with this input stream
} catch (FileNotFoundException ex) {
System.err.println(file.getAbsolutePath());
}

IMDb

We’re building an application which
reads IMDb data and parses it to
determine which actor has made the
best ﬁlms.

Read ﬁles

• Open project SequentialWithoutIO
• Update root ﬁeld in class IMDB
• Find method readFilms() and
readActors() in class IMDB

• Implement!

NIO.2 Hints
/** Read a UTF-16 file like ratings-clean.txt **/
try (BufferedReader reader = Files.newBufferedReader(
file, Charset.forName(“UTF-16”)))

/** Read all actor files in a directory **/
try (DirectoryStream<Path> stream =
Files.newDirectoryStream(dir, “actor*.txt”))

/** Read all lines in file **/
Files.readAllLines(entry, Charset.forName(“UTF-8”));

Parse ﬁles
• Open project SequentialParserWithIO
(or continue with your previous project)
• Update root ﬁeld in class IMDB
• Find method compute() in classes
ActorParseTask and FilmParseTask

• Implement!

Fork/Join Hints
/** Start computing with checking if the work is small
enough to do sequentially **/

/** Fork! **/
Collection<ParseTask> completedForks = invokeAll(
/** give a list work packages **/);

/** Join! **/
for (ParseTask task : completedForks)
/** Join all the results of the tasks and return this
collection **/

Features
• Project Coin 2
• List literals: [1, 2, 3]

• Map literals: [“a”: 1, “b”: 2, “c”: 3]

• Project Lambda: (x, y) => x + y

• Type annotations: List<@NonNull Object>

• Superpackages

Features
• Project Jigsaw
• JDK modularity
• Modular and versioned applications
• Joda Time
• Project HotRockit
• Porting JDeveloper to Netbeans

Java 8 workshop
December 2012
Hopefully...

Java 7 workshop

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