Download Object-Oriented Programming in Java Topic 1: The Java Environment

Air Force Institute of Technology
Electrical and Computer Engineering
Object-Oriented Programming Design
Topic 1:
The Java Environment
Maj Joel Young
[email protected]
30-Apr-17
Maj Joel Young
Object-Oriented
Programming
Design
The Java Environment
• Java code is compiled to an intermediate form called
“bytecode”
• The bytecode is executed by a simulated computer called the
Java Virtual Machine (JVM)
• The JVM translates bytecode instructions to your machine
Java
Code
Java
Compiler
Byte
Code
JVM
CPU
30-Apr-17
Air Force Institute of Technology
Electrical and Computer Engineering
2
Object-Oriented
Programming
Design
The Java Environment
• Java maintains its portability by keeping the bytecode the
same across all platforms
• The JVM specification is open so that vendors can write one
for their platforms
• JVMs available from Sun, IBM, Microsoft, and others
Byte
Code
JVM
CPU
30-Apr-17
Air Force Institute of Technology
Electrical and Computer Engineering
3
Object-Oriented
Programming
Design
Java Programming Environment
• Sun Microsystems Java Development Kit (JDK)
–
–
–
–
Available at www.java.sun.com
Latest version is JDK 1.4.2
Sun refers to all releases after 1.1.8 as “Java 2”
Contains compiler, JVM, and tools
• Java API Docs: http://java.sun.com/j2se/1.3/docs/api/
• Integrated Development Environments
– Features include specialized editors, debuggers, GUI builders … but be
comfortable with command line first
– Recommended – get up to speed fast
– Eclipse – IBM – http://www.eclipse.org/ (JDK 1.3), libre
– DrJava – http://www.drjava.org/, can interface with Eclipse, libre
– TogetherSoft – R:\Simulations\TogetherSoft (Academic Version)
– JBuilder – www.inprise.com/jbuilder (free version)
30-Apr-17
Air Force Institute of Technology
Electrical and Computer Engineering
4
Object-Oriented
Programming
Design
Example Java Program
class HelloWorld
{
static public void main(String args[])
{
// About the simplest program you can
// you can write in Java
// Print “Hello World” to the console
System.out.println(“Hello World”);
}
}
30-Apr-17
Air Force Institute of Technology
Electrical and Computer Engineering
5
Object-Oriented
Programming
Design
Java Programming Environment
• Compiling the program
javac HelloWorld.java
• Running the program
java HelloWorld
• CLASSPATH environment variable
– Do not define it unless you know what you are doing
– If you do define it, ensure you include a period:
set CLASSPATH=.;c:\java;
30-Apr-17
Air Force Institute of Technology
Electrical and Computer Engineering
6