The document summarizes the evolution of Java 7 including: 1. An overview of the history and prerequisites that led to the creation of Java, including how it was initially developed in 1991 for consumer devices. 2. A discussion of the different versions of Java released from JDK 1.0 to Java 7, highlighting improvements in each version. 3. Examples demonstrating new features in Java 7 like strings in switch statements, binary literals, multi-catch exceptions, and try-with-resources statements.

1. Fall 2011
CMPE 202- Software Systems Engineering
Research Project – Java7
Submitted by
Manjula Kollipara
Submitted to
Prof. Paul Nguyen
Date: November 26th 2011
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2. CHAPTER 1.History on Evolution of Java7
1.1 Background
Since 1995, Java has changed our world and our expectations....
With growing technology today, we take it granted that we can be connected and access applications and
its contents anywhere, anytime. This is all because of Java; we expect digital devices to be smarter, more
functional, and way more entertaining.
1.2Prerequisites for the evolution of Java language:
In 1991, a small group of Sun Microsystems engineers called “Green Team” led by James Gosling
decided to develop a language for consumer devices such as cable boxes.
They wanted the language to be
1. small and use efficient code since these devices do not have powerful CPUs.
2. hardware independent since different manufacturers would use different CPUs.
1.3 Conclusion
The above conditions allowed them to decide to compile the code to an intermediate machine-like code
for an imaginary CPU called a virtual machine. Apparently, there is a real CPU that implements this
virtual CPU. This intermediate code (called byte code) is completely hardware independent. The
Interpreter converts the byte code to appropriate machine code. Thus, once the interpreter has been
installed on a computer, it can run any byte coded program.
1.4 Naming Convention:
The Green Team chose C++ as their language and not C, because they wanted the language to be more
object oriented rather than procedural. The original name of the language was “Oak”. Eventually they
discovered that there was already a programming language called “Oak”, so they changed the name of the
language to” Java”.
1.5 Artifacts
The Green project had a lot of trouble getting others interested in Java for smart devices. The Green Team
demonstrated their new language with an interactive, handheld home-entertainment controller that was
originally targeted at the digital cable television industry. Unfortunately, the concept was much too
advanced for them at that time. It was most adaptable for Internet, which was just starting to take off.
Since 1991 Java language has undergone many changes starting from JDK 1.0 to current version Java 7
which was released on July 28 2011.
1.6 Versions: Let us walkthrough on the Java versions starting from its origination till today:
Release Version Code Name Release Date Highlights
JDK 1 Oak/Java 23-Jan-96
JDK 1.1 Java 19-Feb-97 AWT event Model, Java Beans, JDBC
J2SE 1.2 Playground 8-Dec-98 strictfp keyword, Swing- Graphical API
JVM with JIT compiler, Java Plug-in
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3. Java IDL with CORBA, collections
J2SE 1.3 Kestrel 8-May-00 HotSpot, RMI with CORBA, JavaSound
JNDI, JPDA, Synthetic proxy classes
J2SE 1.4 Merlin 6-Feb-02 assert keyword included,
Regular Expressions, Exception chaining
IPv6, Integrated XML parser
Cryptography Extension ( JCE,
JSSE,JAAS)
Java web start
J2SE 5 Tiger 30-Sep-04 Annotations, Auto boxing/unboxing
Enumerations, Varargs, Enhanced
“for each” loop, Concurrency utilities
Java SE 6 Mustang 11-Dec-06 Performance improvements
Java compiler API, GUI improvements
JVM improvement such as
Synchronization
compiler performance optimizations
upgraded garbage-collection algorithms
XX:+DoEscapeAnalysis - allow objects
to be
allocated in stack instead of heap
Java SE 7 Dolphin 28-Jul-11 Stated briefly
1.7 Future Implementation:
Next version of Java8 is planned to be released in Summer 2013. This version will include:
1. Features that were deferred during Java 7 implementation
2. Modularization of the JDK under Project Jigsaw.
3. Support for Lambda Expressions at Language –Level.
4. Integration with JavaFX.
1.8 Discovery of Java 7 Features:
With the sufficient information on history, prerequisite’s, naming conventions, artifacts and versions on
Java language; let us now focus more on Java 7 features as listed below.
Java Programming Language
 Binary Literals
 Strings in switch Statements
 The try-with-resources Statement
 Catching Multiple Exception Types and Rethrowing Exceptions with Improved
Type Checking
 Underscores in Numeric Literals
 Type Inference for Generic Instance Creation
 Improved Compiler Warnings and Errors When Using Non-Reifiable Formal
Parameters with Varargs Methods
Swing, IO and New IO, Networking
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4. Security, Concurrency Utilities
Rich Internet Applications (RIA)/Deployment
 Requesting and Customizing Applet Decoration in Dragg able Applets
 Embedding JNLP File in Applet Tag
 Deploying without Codebase
 Handling Applet Initialization Status with Event Handlers
Java 2D, Java XML - JAXP, JAXB, and JAX-WS
Java.lang Package; Multithreaded Custom Class Loaders in Java SE 7
Java Virtual Machine (JVM)
 Java Virtual Machine Support for Non-Java Languages
 Garbage-First Collector
 Java HotSpot Virtual Machine Performance Enhancements
CHAPTER 2. Existing Examples using Java 7 features
Now let us look at some of the examples using Java 7 features.
2.1 ProgrammingLanguage
2.1.1String in Switch statement: One other language that implements this feature is Shell scripting in
Linux.One of the most easy-to-usefeatures implemented in Java 7 is having strings in switch
statement.With this, the code is more readable and also the compiler can generate efficient byte code.
public static void main(String[] args) throws IOException {
reader = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Please enter you choice of version");
version = reader.readLine();
switch (version)
{
case "java5": System.out.println("Yes, you entered java5"); break;
case "java6": System.out.println("Your Entry was java6"); break;
case "java7": System.out.println("Current version is java7");
break;
}
2.1.2 Binary Literals:
Public void testBinaryIntegralLiterals(){
int binary = 0b1000;
If(binary == 8){
System.out.println(true);}
Else{
System.out.println(false);}
}
2.1.3Multi-Catch:
The below part of the code is from the Project-coin that implemented most of the Java 7 features.
Public static void printBalance(String accountId){
Try{
BigDecimal balance = getBalance(accountId);
}
Catch(AccountFrozenException |
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5. ComplianceViolationException |
AccountClosedException e)
{
System.out.println(“Please visit your local branch office for further help”);}
}
2.1.4 Try-catch Method:
Public static void Main(string[] args)
{
// Creating an object of the FileStream class
//Note: One file named as Write should in 'Test' folder in 'C' drive.
try(FileStreamfs = new FileStream(@"C:TestWrite.txt", FileMode.Open)){
StreamReadersr = new StreamReader(fs);
// Reading data from the file
String str = sr.ReadLine();
Console.WriteLine("Text from the file is as follows:");
Console.WriteLine(str);
sr.Close();
fs.Close();
} catch(exception e){}
}
2.1.5 Underscores between literals: In Java 7 we can use “_” (underscore) as part of literal.
Public void testUnderScoreNumericLiterals(){
intoneMillion_ = 1_000_000;
IntoneMillion = 1000000;
If(oneMilion_ == oneMillion){
System.out.println(true);}
Else{
System.out.println(false);
}
}
Some of the rules to be followed before using “_” in literal:
1. It is not legal to start literal value with “_” : Example: int x=_1000;
2. Literal should not end with Underscore. Ex: int l= 1000_;
3. Underscored can be implemented after the decimal point.: Example: float x=2.323_000
4. Underscores can be included in other numeric typesalso.Ex: int bytes = 0x123_456
5. consequitive underscored are not allowed. Example: int I = 100____000;
6. Underscored are not allowed before and after the decimal point.
Ex: double d = 1000_.000, e= 1000._000;
2.1.6 Type reference for generic instance creation; Diamond syntax
Map<String, List<String>> map = new HashMap<>();
{
GCDemoobj = newGCDemo();
}
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6. Console.WriteLine("");
}
}
}
CHAPTER 3 My Contribution on using Java7 features
I am applying the below 3 features in fnding nth Fibonacci number. The features are:
1: Used multi-catch feature
2: Used fork-Join implemented in computing nth Fibonacci number
3: Automatic type reference
/* @author = Manjula Kollipara SID = 008077680 */
packagemanjulak; // manjulak is a folder name
importjava.util.*;
importjava.util.Map;
importjava.util.concurrent.ConcurrentHashMap;
importjava.util.concurrent.ForkJoinPool;
importjava.util.concurrent.RecursiveTask;
classFibCache {
// Java7: automatic type inference
public static ConcurrentHashMap<Integer, Long>resultsCache = new
ConcurrentHashMap<>(1000);
}
classFibBasic {
publicint nth;
publicFibBasic() {
}
publicFibBasic(int nth) {
this.nth = nth;
}
public static long compute(int n) {
long result = n;
Long cache;
if (n > 1) {
cache = FibCache.resultsCache.get(n);
if (cache == null) {
result = compute(n-1) + compute(n-2);
FibCache.resultsCache.put(n, result);
} else {
result = cache;
}
}
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7. return result;
}
public long compute() {
System.out.println(Thread.currentThread().getName() + ": " + nth);
return compute(nth);
}
}
classFibTask extends RecursiveTask<Long> {
privateint nth;
private static intfork_join_threshold = 10;
publicFibTask(int n) {
this.nth = n;
}
// Java7: FORK-JOIN
@Override
public Long compute() {
long result = 0;
if (nth <= this.fork_join_threshold) {
//System.out.println(Thread.currentThread().getName() + ": " + nth);
result = new FibBasic().compute(nth);
return result;
}
Long cachen1 = null, cachen2 = null;
inttmp;
cachen1 = FibCache.resultsCache.get(nth-1);
cachen2 = FibCache.resultsCache.get(nth-2);
List<FibTask>subTasks = new LinkedList<>();
if (cachen1 == null) {
subTasks.add(new FibTask(nth-1));
} else {
result += cachen1;
tmp = nth-1;
//System.out.println(Thread.currentThread().getName() + ": found cache: ["
+ tmp + "] -> " + cachen1);
}
if (cachen2 == null) {
subTasks.add(new FibTask(nth-2));
} else {
result += cachen2;
tmp = nth-2;
//System.out.println(Thread.currentThread().getName() + ": found cache: ["
+ tmp + "] -> " + cachen2);
}
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8. for (RecursiveTask<Long> task : subTasks) {
task.fork();
}
for (FibTask task : subTasks) {
result += task.join();
}
//System.out.println(Thread.currentThread().getName() + ": " + nth);
FibCache.resultsCache.put(nth, result);
//System.out.println(Thread.currentThread().getName() + ": update cache: [" +
nth + "] <- " + result);
return result;
}
}
public class j7demo {
/**
* @paramargs the command line arguments
*/
public static void main(String[] args) {
intsysCpus = Runtime.getRuntime().availableProcessors();
intcpuArg = 0, fibNum = 0;
long result = 0;
longtotalFJTime = 0, totalTime = 0;
// Java7: Multi-Catch
try {
fibNum = Integer.parseInt(args[1]);
cpuArg = Integer.parseInt(args[2]);
if (cpuArg>sysCpus) cpuArg = sysCpus;
} catch (ArrayIndexOutOfBoundsException | NumberFormatException e) {
cpuArg = sysCpus;
}
ForkJoinPooltaskPool = new ForkJoinPool(cpuArg);
FibTaskfibTask = new FibTask(fibNum);
// compute non-fork-join timing (recursive method)
totalTime = System.currentTimeMillis();
result = FibBasic.compute(fibNum);
totalTime = System.currentTimeMillis() - totalTime;
// clear cache for fj method
FibCache.resultsCache.clear();
// compute fork-join timing (recursive & for-join method)
totalFJTime = System.currentTimeMillis();
result = taskPool.invoke(fibTask);
totalFJTime = System.currentTimeMillis() - totalFJTime;
System.out.println("cpuArg: " + cpuArg +", fibNum: " + fibNum + ", result: " + result
+
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9. ", FJ-time: " + totalFJTime + "ms" + ", non-FJ-time: " + totalTime +
"ms");
return;
}
}
Output:
References
[1] http://wikipedia.org
[2] http://www.oracle.com/technetwork/java/javase/jdk7-relnotes-418459.html
[3] http://java.dzone.com/articles/new-java-7-language-features
[4] http://java.dzone.com/articles/java-7-%E2%80%93-project-coin-feature
[5] http://docs.oracle.com/javase/7/docs/technotes/guides/language/try-with-resources.html
[6] http://java.dzone.com/articles/new-java-7-language-features
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