مفاهيم البرمجة وتدفق البيانات

Introduction to Java Programming

• Java is a powerful language for developing various applications, including standalone desktop applications, internet applications, and mobile applications (like cell phones and e-readers).
• Sun Microsystems invented and developed Java. Oracle now owns Java.
• The goal of Java was to create a programming language capable of operating systems for all devices, from large mainframes to small MP3 players.

Java Programming Fundamentals

• A Java development toolkit (JDK) is required for Java programming.
• This toolkit includes essential programs for writing, translating (compiling), and debugging Java code.
• Various methods for writing and translating Java programs include using the JDK with text editors like Notepad, or specialized development environments like NetBeans, JCreator, or BlueJ.

Java Structure

• A Java program consists of a source code, a compiler, bytecodes, and virtual machines.
• The source code is the Java program written by the programmer.
• The compiler translates the source code into bytecodes.
• Virtual machines run the bytecodes and execute the program on different devices.

Java Versions

• J2SE (Java 2 Standard Edition): Used to develop and run desktop applications.
• J2EE (Java 2 Enterprise Edition): Used for large-scale enterprise applications.
• J2ME (Java 2 Micro Edition): Designed for mobile and wireless devices.

Java Features

• Platform independence: Java programs can run on different operating systems without modification.
• Object-oriented programming (OOP): An approach for programming using objects that have data and functions. This is different from traditional programming which uses functions.
• Graphical user interface (GUI) capabilities: Java supports building applications with user-friendly interfaces.
• Java Applets: A type of application designed for the internet, embedding it in HTML pages on a server.

Java Program Structure

• A Java program typically has a class that includes a main method.
• The main method contains the program's statements, which are the executable part of the program

Java Data Types & Variables

• Java has various data types like integer, floating-point, character, and boolean.
• Integer types (byte, short, int, long) store whole numbers.
• Floating-point types (float, double) store decimal numbers.
• Character type (char) stores single characters.
• Boolean type (boolean) stores true or false values.

Output Statements and Printing

• System.out.print: Prints output to the console without moving to a new line.
• System.out.println: Prints output to the console and moves to a new line after the output.
• Escape sequences (\n, \t, \r, \, "): Used for special characters within print statements.

Java Comments

• // Single-line comment
• /* Multi-line comment */

Input in Java

• Scanner: A class from the java.util package, for accepting user input from the keyboard. It needs to be imported: import java.util.Scanner;
• Keyboard.nextInt(): Reads an integer value from the user.
• Keyboard.nextDouble(): Reads a double value from the user.
• Keyboard.next(): Reads a String value from the user.
• Keyboard.nextLine(): Reads a line of input (including spaces) from the user

Control Statements (if-else, switch)

• if (condition) executes a block of code if the condition is true; else if and else provide alternatives for conditions.
• switch (expression) evaluates the expression and jumps to the corresponding case block.

Loops (for, while, do-while)

• for (initialization; condition; increment): Used for repeated execution of a block of code.
• while (condition): Executes a block of code as long as the condition is true.
• do { ... } while (condition): Executes a block of code at least once and repeatedly as long as the condition is true.

Methods in Java

• Methods are reusable blocks of code that encapsulate specific tasks.
• void: Indicates that the method does not return any value.
• return: Used in methods to send a value back to the calling part of the code.

Arrays in Java

• Arrays are used to store a collection of data of the same data type.
• DataType[] array_name = new DataType[size]: Declaration and initialization of an array.
• An array index starts at 0. e.g., array[0] is the first element.