Introduction to Java

Computer Engineering DepartmentSharif University of Technology

1st Quiz

2

1st Quiz

1.What is Object?

2.What is Class?

3.What are the properties of an Object Oriented Programming? Define them!

2

1st Quiz

1.What is Object?

2.What is Class?

3.What are the properties of an Object Oriented Programming? Define them!

2

Your Time is Finished

Programming Language

3

Programming Language

3

• A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer.

• PLs should support

• Data type, Sequence control, Object, Class, ...

• Java is an OOPL.

Interpret vs. Compile

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Interpret vs. Compile

4

• Compile

• The program written in a language is translated to another language by another program named compiler.

• Interpret

• The program written in a language is executed statement by statement by another program named interpreter.

5

C

C++

Pascal

Pascal Compiler for Linux

C++ Compiler for Mac

C Compiler for Windows

Pascal Compiler for Windows

Pascal Compiler for Mac

C Compiler for Mac

C Compiler for Linux

C++ Compiler for Mac

C++ Compiler for Mac

Platform and Compiler

Platform Independency

6

Slot 1

Slot 2

Slot 3

The

Device

Platform Independency

6

Slot 1

Slot 2

Slot 3

The

Device

When we have different platforms and a single device,

what can we do to support this device on all platforms?

Platform Independency

6

Slot 1

Slot 2

Slot 3

The

Device

When we have different platforms and a single device,

what can we do to support this device on all platforms?

Entering the Java world!

Edit your java files

Compile your files

Run the class file

Java file

Class file

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Entering the Java world!

• A Java file contains a class.

• A class contains a main function.

• Java file compiled to byte code file (class file)

• You can run your class.

Edit your java files

Compile your files

Run the class file

Java file

Class file

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1st Exercise8

/* * This is your first java program. */

class HelloWorld{public static void main(String[] args){System.out.println(“Hello World!”);

}}

Edit your java file

9

Edit your java file

• Any editor can be used

• VIM, Gedit, Textpad, Kedit, Textedit, Notepad, ...

• It’s much more simpler if you use an IDE

• Eclipse, IDEA, Forte, NetBeans, ...

• Java files have .java extension.

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Java Compilation

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Java Compilation

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• The Java Compiler (javac) is used to compiler Java sources into byte code files.

• javac is just available in the Java SDK not JRE.

• Byte code files have .class extension.

• Byte code is the assembly language for the Java Virtual Machine (JVM).

Compile HelloWorld

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$javac HelloWorld.java

Compile HelloWorld

• Java files can be compiled with javac (Java Compiler)

• Now a file named HelloWorld.class is generated.

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$javac HelloWorld.java

Running Java Classes

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Running Java Classes

• Java Virtual Machine (JVM) is used for running class files.

• JVM can run class files.

• Now, there are officially supported JVMs for Linux, Windows, Mac OS X and Solaris.

• JVM is also available for FreeBSD, AIX, Darwin, ...

12

Run HelloWorld

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$java HelloWorld

Run HelloWorld

• Use java to run the class file.

13

$java HelloWorld

Any Questions?