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1 OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Java Pros and Cons − Roundtable American Nuclear Society Annual Meeting June 16, 2004 Pittsburgh, PA
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Java Pros and Cons − Roundtable
American Nuclear Society
Annual Meeting
June 16, 2004 Pittsburgh, PA
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Java – an Object-Oriented Programming Language
Based on objects: data and methods together
Four Concepts: Abstraction – describes physical world Encapsulation – data and methods together Inheritance - just like something else but ... Polymorphism – method overloading
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Abstraction / Encapsulation public class Particle {
Position position;
Direction direction;
double energy;
public Particle(){
position = new Position(0, 0, 0);
direction = new Position(1, 0, 0);
energy = 1.0;
}
public void move(double distance){
position.move(direction, distance);
}
public void scat(double t, double p){
...
}
}
public class Position {
double x, y, z; public Position(double a, double b, double c){ x = a; y = b; z = c; }
public void move(Direction d, double dis){ x = x + d.u*dis; y = y + d.v*dis; z = z + d.w*dis; }
public double howFarTo(Position p){ double answer = (p.x-x)*(p.x-x) + (p.y-y)*(p.y-y) + (p.z-z)*(p.z-z); answer = Math.sqrt( answer ); return answer; }}
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Inheritance (1/2)
public class ChargedParticle extends Particle {
double restMass; int charge;
// Physical Constants static double ELEMCHARGE = 1.60217733e-19; // Coulombs static double RESTMASSKG = 9.1093897e-31; // kg static double RESTMASS = 0.511; // MeV static double ERADIUS = 2.81792e-15; // meter
public ChargedParticle(){ super(); restMass = ChargedParticle.RESTMASS; charge = -1; }
public double getSpeed(){ double speed = ... (energy-restMass) ... return speed; }
}
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Inheritance (2/2)
public class Photon extends Particle {
// Physical Constants static double speedOfLight = 299792458.0; // m/s static double planckConstant = 6.6260755e-34; // Joule seconds
public Photon(){ super(); }
public Particle[] comptonScatter(){ Particle[] answer = new Particle[2]; // photoelectron answer[0] = new ChargedParticle(...);
// scattered photon answer[1] = new Photon(...);
return answer; }}
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Polymorphismpublic class Particle {
Position position; Direction direction; double energy; public Particle(){ position = new Position(0, 0, 0); direction = new Position(1, 0, 0); energy = 1.0; } public Particle(Position p, Direction d, double e){ position = p direction = d; energy = e; }
public Particle(Particle p){ position = p.position; direction = p.direction; energy = p.energy; }
}
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Java Pros Free, freely distributable Portable – “Write once, run anywhere” Internet savvy Extensive libraries – database, GUI,
networking, etc. Language – strongly typed, array indices
are checked, automatic garbage collection, Threads, Exceptions
*.jar files – Java archive, runnable
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Java Cons Interpreted
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Java 1.5 “Tiger”
Generics - no casting, errors at compile time, not runtime
Enhanced for Loop Autoboxing/Unboxing -
collections of primitive data types
Formatted Output - more like C or FORTRAN
New JVM Profiling API Improved Diagnostic
Ability - getStackTrace, Thread.getAllStackTraces
private void printCollection(Collection c) { Iterator<String> i = c.iterator(); while(i.hasNext()) { String item = i.next(); System.out.println("Item: "+item); }}
public void newFor(Collection<String> c) { for(String str : c) { System.out.println(str); }}
System.out.printf("%s %3d", name, age);
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Sun Microsystems, Inc.Binary Code License Agreement
for theJAVATM 2 SOFTWARE DEVELOPMENT KIT (J2SDK),
STANDARD EDITION, VERSION 1.4.2_X
3. RESTRICTIONS. ... You acknowledge that Licensed Software is not designed or intended for use in the design, construction, operation or maintenance of any nuclear facility. ...
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Sun Microsystems, Inc.Binary Code License Agreement
for theJAVATM 2 SOFTWARE DEVELOPMENT KIT (J2SDK),
STANDARD EDITION, VERSION 1.4.2_X
3. RESTRICTIONS. ... You acknowledge that Licensed Software is not designed or intended for use in the design, construction, operation or maintenance of any nuclear facility. ...
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OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Any Questions?
