Java 6 -> Java 7 reference: NIO, Exception, Join Fork framework, Syntax

1. Just to drink a cup of coffee
refence guide: from java 6 to java 7 (SE)
Syntax
Compiler infers the generic type parameters
Improving variables declarations
Numbers litterals
Improving numebr reading (really?)
String switch
Exception
Catch more exceptions
Avoiding code redundancy
Try with resources
Avoiding “if/try/catch/finally nightmare”
Multithread
Fork and Join Framework
Parallel computing
NIO
deleteIfExists, …
...and a lot of stuff
File Watcher
Java Typed
java.lang.invoke
Not typed language are easy

2. Compiler infer the generic type parameters
Java 6
bject> objects = new LinkedList<MyObject>();
Java 7
List<MyObject> objects = new Lin

3. Numbers
Java 6
int i = 1000;
int j =1000000
Java 7
int i = 1_000;
int j = 1_000_000;
Wrong syntax
int x = _1_000_000;

4. String switch
Java 6
String a,b,c;
if (a.equals(b)) {
} else if (a.equals(c)) {
}
Java 7
String a,b,c;
switch (a) {
b:
break;
c:
break;
}

5. Catch more exceptions
Java 6
try {
...
} catch(NumberFormatException e) {
logError(e);
} catch(NullPointerException e) {
logError(e);
}
Java 7
try {
...
} catch(NumberFormatException |
logError(e);
}

6. Try with resources
(implements Closeable or AutoCloseable)
Java 6
FileReader r = null;
try{
r = new FileReader(file);
BufferedReader reader = new BufferedReader(r);
String line = reader.readLine();
while (line != null) {
lines.add(line);
line = reader.readLine();
}
} catch(IOException e) {
logError(e);
} finally {
if (r!=null) r.close();
}
Java 7
try(BufferedReader reader = new BufferedReader(
String line = reader.readLine();
while (line != null) {
lines.add(line);
line = reader.readLine();
}
}

7. Join Fork Framework
more powerfull than the code described here [http://www.oracle.com/technetwork/articles/java/fork-join-422606.ht
Java 6
FutureTask<String> myFutureAction = new FutureTask<String>(
new Callable<String>()
{
public MyObject call() {
Return ...;
}
});
ExecutorService executor = Executors.newFixedThreadPool(1);
FutureTask<Object> futureOne = new FutureTask<Object>(myFutureAction);
executor.execute(future);
…//sleep
executor.shutdown();
Java 7
public class ForkAction extends RecursiveAct
ParamObject from = null;
ForkAction(ParamObject from, ParamObject to)
this.from=from;
...
}
@Override
public MyObject compute() {
...
}
}
...
ForkJoinPool forkJoinPool = new ForkJoinPool
forkJoinPool.invoke(new ForkAction(from, to)

8. NIO deleteIfExists, ...
Java 6
try {
Files.delete(path);
} catch(NoSuchFileException e){}
Java 7
Files.deleteIfExists(path);
and a lot of stuff
Files.createSymbolicLink(...)
Files.copy(...)
Files.move(...)

9. NIO WatcherService
Java 6
while (true) {
File myDir = …
pollForChanges(myDir);
}
public void pollForChanges(File myDir) {
//list dir
//use apache common io
}
Java 7
Path pathToWatch = Paths.get("/tmp");
PathToWatch.register(FileSystems.getDefault(
while (true) {
WatchKey key = watchService.take();
}

10. NIO WatcherService
Java 6
while (true) {
File myDir = …
pollForChanges(myDir);
}
public void pollForChanges(File myDir) {
//list dir
//use apache common io
}
Java 7
Path pathToWatch = Paths.get("/tmp");
PathToWatch.register(FileSystems.getDefault(
while (true) {
WatchKey key = watchService.take();
}

11. java.lang.invoke
Java 6
class MyClass {
public void myMethod(int i, String j) {
...
}
}
...
Class<?>[] argTypes = new Class[] { int.class, String.class };
meth = MyClass.class. getDeclaredMethod("myMethod", argTypes);
meth.invoke(new MyClass(), 2, "EFG");
Java 7
class MyClass {
public void myMethod(int i, String j) {
...
}
}
...
MethodHandle mh;
MethodType desc = MethodType.methodType(v
mh = MethodHandles.lookup().findVirtual(M
mh.invokeExact(new MyClass(), 1, "ABCDE")