Embed Size (px)
DESCRIPTION
Algorithm Programming 1 (using Java) 89-210. Bar-Ilan University 2007-2008 תשס"ח by Moshe Fresko. Course objectives. Learning Professional Programming by Algorithmic Examples Learning Java Object Oriented Programming Design Patterns Multithreaded Programming GUI - PowerPoint PPT Presentation
Citation preview
Algorithm Programming 1(using Java) 89-210
Bar-Ilan University
תשס"ח 2007-2008
by Moshe Fresko
Course objectives Learning Professional Programming
by Algorithmic Examples Learning Java Object Oriented Programming Design Patterns Multithreaded Programming GUI Run-time Class Information
Course Requirements Exercises/Projects, 25 % of the grade
Programming Exercises One step-by-step Project Time schedules are strict, no late exercises are
accepted. They will be handed on via the Department
Submitec utility Cheating is punished by Discipline Assembly
( Very strictly ) Exam 75 %
What is Java ? (Almost) Fully OO Programming Language. Syntax: Similar to C++, Different in some
Semantics and Internals. Architecture Neutral World-Wide-Web programming language
History Early 1990s, Oak, by Sun
For embedded systems in Consumer Electronic Devices 1994, Sun decided to adapt Oak to Web January 1995, renamed as Java,
Building Web based applications May 1995, Sun’s first JDK (Java Development Kit)
With HotJava capable of running Applets 1998, Sun released Java 2 SDK (J2SDK)
By time Bunch of Libraries are added
Object Oriented Reminders Abstraction Encapsulation Inheritance Abstract classes Polymorphism
By Inheritance By Overloading Interfacing
Constructors and Finalizers
Design Patterns Design Patterns help you learn from others’
successes, instead of your failures Separate things that change, from the things
that doesn’t change Elegant and Cheap-to-Maintain Inheritance can be thought as a DP, and so
Composition, etc. Iterator (Enumeration in Java 1.0 and 1.1)
Resources Internet
http://java.sun.com For Tutorials and Downloads http://java.sun.com/j2se/1.4.2/docs/api/ API of Java 1.4 http://java.sun.com/j2se/1.5.0/docs/api/ API of Java 1.5 http://java.sun.com/docs/books/tutorial/reallybigindex.html Development Environment
NetBeans ide Symantec’s Cofe Borland’s JBuilder
Books Developing Java Software
Russel Winder & Graham Roberts 2nd Edition, 2000 John Wiley and Sons, Ltd.
Java 2 CompleteGemma O’Sullivan1998, Sybex
Thinking in JavaBruce Eckel 3rd Edition (free to download)
Design PatternsErich Gamma, Richard Helm, Ralph Johnson, John Vlissides1995, Addison Wesley
Other Java Books …
JDK, J2SE J2SE, J2EE and J2ME
JFC : Java Foundation Classes Java2D : 2D Graphics JavaBeans : Java object component technology Servlets : Web Server JavaHelp : For creating help systems etc.
javac : Compiler to Byte-Code java : Loads a byte-code into JVM and executes javap : Byte-code viewer javadoc : Creates HTML documentation for the code. jdb : Java debugger appletviewer : To view applets from within an HMTL page
Application Example Programs
Applications Applets
Programs are Case Sensitive
Example: HelloWorldApp.java file
public class HelloWorldApp { public static void main(String[] args) {
System.out.println("Hello World!"); }
}
Application Example javac HelloWorldApp.java
Compiles and creates ByteCode in file “HelloWorldApp.class”
java HelloWorldApp Looks for the file “HelloWorldApp.class”
and for the class “HelloWorldApp” in it, and starts to run the static “main” function.
Applet Example// HelloWorld.java fileimport java.applet.*;import java.awt.*;public class HelloWorld extends Applet { public void paint(Graphics g) { g.drawString("Hello world!", 50, 25); }}
// Hello.html file<HTML><HEAD><TITLE>A Simple Program</TITLE></HEAD><BODY>Here is the output of my program:<APPLET CODE="HelloWorld.class" WIDTH=150 HEIGHT=25></APPLET></BODY></HTML>
JVM Source Code Java Compiler (javac) -> ByteCode Java Interpreter (java) - Java VM
JVM java -classpath …;…;…
for providing paths of class libraries, and .jar files .jar files are a set of class files compressed into a single file
ClassClass Class Class
Execution Engine
Adapter Interface
Adapter
OS
JNI
Java Bytecode
Like C++ Assembly, JavaByteCode
We need to check ByteCode For Performance and Memory Usage Tuning Size and Execution Speed Debugging
Java Bytecode - Exampleclass Employee {
private String name ;private int idNumber ;public Employee(String strName, int num) {
name = strName ;idNumber = num ;storeData(strName,num) ;
}public String employeeName() {
return name ;}public int employeeNumber() {
return idNumber ;}private void storeData(String s, int num) {// ...}
}
javac Employee.java creates Employee.classjavap –c Employee to print to string the byte-code in visual form
Java Bytecode - ExampleCompiled from "Employee.java"class Employee extends java.lang.Object{public Employee(java.lang.String,int); Code: 0: aload_0 1: invokespecial #1;
//Method java/lang/Object."<init>":()V 4: aload_0 5: aload_1 6: putfield #2;
//Field name:Ljava/lang/String; 9: aload_0 10: iload_2 11: putfield #3;
//Field idNumber:I 14: aload_0 15: aload_1 16: iload_2 17: invokespecial #4;
//MethodstoreData:(Ljava/lang/String;I)V 20: return
public java.lang.String employeeName(); Code: 0: aload_0 1: getfield #2;
//Field name:Ljava/lang/String;
4: areturnpublic int employeeNumber(); Code: 0: aload_0 1: getfield #3;
//Field idNumber:I 4: ireturn}
Java Bytecode - opcodes opcodes
a... : opcode is manipulating type object ref. i… : opcode is manipulation type integer b… : byte, c... : char, d… : double, etc.
Java Bytecode - JVM JVM
Stack-based machine Each thread has a JVM stack which stores Frames A frame is created each time a method is invoked Each Frame has
Operand Stack An array of Local variables A reference to Runtime constant pool of the class of
the current method
Java Bytecode – JVM diagram
Java Bytecode Local variables
0th : this (for constructors or instant methods) Then parameters Then local variables
Operand stack LIFO stack, to pop and push values Used to receive return values
Examplepublic string employeeName() { return name ; }public java.lang.String employeeName(); Code: 0: aload_0 1: getfield #2; //Field name:Ljava/lang/String; 4: areturn
aload_0 : pushes this pointer into stack getfield #2 : this popped+2 added and get reference (for name) from runtime constant pool of
the class. This is loaded to the stack areturn : returns the top value of the stack (name). It is popped from operand stack and pushed
to the operand stack of calling method The real machine code is : 2A B4 00 02 B0
Java Bytecodepublic Employee(String strName, int num) {
name = strName ;idNumber = num ;storeData(strName,num) ;
}
public Employee(java.lang.String,int); Code: 0: aload_0 1: invokespecial #1; //Method java/lang/Object."<init>":()V 4: aload_0 5: aload_1 6: putfield #2; //Field name:Ljava/lang/String; 9: aload_0 10: iload_2 11: putfield #3; //Field idNumber:I 14: aload_0 15: aload_1 16: iload_2 17: invokespecial #4; //Method storeData:(Ljava/lang/String;I)V 20: return
String and StringBuffer In package java.lang StringBuffer is modifiable version of String class String has
length substring extraction Finding and matching String comparison Uppercase and lowercase conversion Leading and trailing whitespace elimination Conversion to/from char arrays Conversion from primitive types to String Appending strings Inserting strings
