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| 1 | - | # VERRY Basic Introduction to Java Programming | |
| 1 | + | # VERRRRRRY Basic Introduction to Java Programming | |
| 2 | 2 | ||
| 3 | 3 | ## 1. Basic Program Structure | |
| 4 | 4 | Every Java program starts with a class, and the main method is the entry point of the program. Here's a simple example: | |
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javaintro.md
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| 1 | - | # Introduction to Java Programming | |
| 1 | + | # VERRY Basic Introduction to Java Programming | |
| 2 | 2 | ||
| 3 | 3 | ## 1. Basic Program Structure | |
| 4 | 4 | Every Java program starts with a class, and the main method is the entry point of the program. Here's a simple example: | |
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javaintro.md
| @@ -118,6 +118,9 @@ public class ArrayExample { | |||
| 118 | 118 | Methods help you organize code into reusable blocks: | |
| 119 | 119 | ||
| 120 | 120 | ```java | |
| 121 | + | // | |
| 122 | + | // If you put all this into a filename `Methods.java` | |
| 123 | + | // | |
| 121 | 124 | public class Methods { | |
| 122 | 125 | public static void main(String[] args) { | |
| 123 | 126 | // Calling methods | |
| @@ -140,7 +143,8 @@ public class Methods { | |||
| 140 | 143 | ||
| 141 | 144 | These examples cover the fundamental concepts you'll need to start programming in Java. Remember to: | |
| 142 | 145 | - Save each class in a separate file with the same name as the class | |
| 143 | - | - Compile your code using `javac FileName.java` | |
| 144 | - | - Run your program using `java FileName` | |
| 146 | + | - So to try `Methods.java` | |
| 147 | + | - Compile your code using `javac Methods.java` | |
| 148 | + | - Run your program using `java Methods` | |
| 145 | 149 | ||
| 146 | 150 | Practice with these examples and modify them to experiment with different values and behaviors. This hands-on experience will help solidify your understanding of Java basics. | |
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| 1 | + | # Introduction to Java Programming | |
| 2 | + | ||
| 3 | + | ## 1. Basic Program Structure | |
| 4 | + | Every Java program starts with a class, and the main method is the entry point of the program. Here's a simple example: | |
| 5 | + | ||
| 6 | + | ```java | |
| 7 | + | public class HelloWorld { | |
| 8 | + | public static void main(String[] args) { | |
| 9 | + | System.out.println("Hello, World!"); | |
| 10 | + | } | |
| 11 | + | } | |
| 12 | + | ``` | |
| 13 | + | ||
| 14 | + | This structure is fundamental to Java: | |
| 15 | + | - `public class`: Declares a class that can be accessed from anywhere | |
| 16 | + | - `static void main(String[] args)`: The main method that runs when you execute the program | |
| 17 | + | - `System.out.println()`: Prints text to the console | |
| 18 | + | ||
| 19 | + | ## 2. Variables and Data Types | |
| 20 | + | Java is a strongly-typed language, meaning you must declare the type of each variable. Here are the basic data types: | |
| 21 | + | ||
| 22 | + | ```java | |
| 23 | + | public class Variables { | |
| 24 | + | public static void main(String[] args) { | |
| 25 | + | // Numeric types | |
| 26 | + | int age = 25; // Whole numbers | |
| 27 | + | double price = 19.99; // Decimal numbers | |
| 28 | + | ||
| 29 | + | // Text | |
| 30 | + | char grade = 'A'; // Single character | |
| 31 | + | String name = "John Doe"; // Text string | |
| 32 | + | ||
| 33 | + | // Boolean | |
| 34 | + | boolean isStudent = true; // true or false | |
| 35 | + | ||
| 36 | + | // Printing variables | |
| 37 | + | System.out.println("Name: " + name); | |
| 38 | + | System.out.println("Age: " + age); | |
| 39 | + | System.out.println("Grade: " + grade); | |
| 40 | + | } | |
| 41 | + | } | |
| 42 | + | ``` | |
| 43 | + | ||
| 44 | + | ## 3. Control Flow Statements | |
| 45 | + | Control flow statements help you make decisions and repeat actions in your code. | |
| 46 | + | ||
| 47 | + | ### If-Else Statements | |
| 48 | + | ```java | |
| 49 | + | public class ControlFlow { | |
| 50 | + | public static void main(String[] args) { | |
| 51 | + | int score = 85; | |
| 52 | + | ||
| 53 | + | if (score >= 90) { | |
| 54 | + | System.out.println("Excellent!"); | |
| 55 | + | } else if (score >= 80) { | |
| 56 | + | System.out.println("Good job!"); | |
| 57 | + | } else { | |
| 58 | + | System.out.println("Keep practicing!"); | |
| 59 | + | } | |
| 60 | + | } | |
| 61 | + | } | |
| 62 | + | ``` | |
| 63 | + | ||
| 64 | + | ### Loops | |
| 65 | + | ```java | |
| 66 | + | public class Loops { | |
| 67 | + | public static void main(String[] args) { | |
| 68 | + | // For loop | |
| 69 | + | System.out.println("Counting with for loop:"); | |
| 70 | + | for (int i = 1; i <= 5; i++) { | |
| 71 | + | System.out.println("Count: " + i); | |
| 72 | + | } | |
| 73 | + | ||
| 74 | + | // While loop | |
| 75 | + | System.out.println("\nCounting with while loop:"); | |
| 76 | + | int count = 1; | |
| 77 | + | while (count <= 5) { | |
| 78 | + | System.out.println("Count: " + count); | |
| 79 | + | count++; | |
| 80 | + | } | |
| 81 | + | } | |
| 82 | + | } | |
| 83 | + | ``` | |
| 84 | + | ||
| 85 | + | ## 4. Arrays | |
| 86 | + | Arrays allow you to store multiple values of the same type: | |
| 87 | + | ||
| 88 | + | ```java | |
| 89 | + | public class ArrayExample { | |
| 90 | + | public static void main(String[] args) { | |
| 91 | + | // Declaring and initializing an array | |
| 92 | + | int[] numbers = {1, 2, 3, 4, 5}; | |
| 93 | + | ||
| 94 | + | // Accessing array elements | |
| 95 | + | System.out.println("First number: " + numbers[0]); | |
| 96 | + | ||
| 97 | + | // Array iteration | |
| 98 | + | System.out.println("\nAll numbers:"); | |
| 99 | + | for (int number : numbers) { | |
| 100 | + | System.out.println(number); | |
| 101 | + | } | |
| 102 | + | ||
| 103 | + | // Creating an array of strings | |
| 104 | + | String[] fruits = new String[3]; | |
| 105 | + | fruits[0] = "Apple"; | |
| 106 | + | fruits[1] = "Banana"; | |
| 107 | + | fruits[2] = "Orange"; | |
| 108 | + | ||
| 109 | + | System.out.println("\nFruits:"); | |
| 110 | + | for (String fruit : fruits) { | |
| 111 | + | System.out.println(fruit); | |
| 112 | + | } | |
| 113 | + | } | |
| 114 | + | } | |
| 115 | + | ``` | |
| 116 | + | ||
| 117 | + | ## 5. Methods | |
| 118 | + | Methods help you organize code into reusable blocks: | |
| 119 | + | ||
| 120 | + | ```java | |
| 121 | + | public class Methods { | |
| 122 | + | public static void main(String[] args) { | |
| 123 | + | // Calling methods | |
| 124 | + | greet("Alice"); | |
| 125 | + | int sum = add(5, 3); | |
| 126 | + | System.out.println("Sum: " + sum); | |
| 127 | + | } | |
| 128 | + | ||
| 129 | + | // Method with no return value (void) | |
| 130 | + | public static void greet(String name) { | |
| 131 | + | System.out.println("Hello, " + name + "!"); | |
| 132 | + | } | |
| 133 | + | ||
| 134 | + | // Method that returns a value | |
| 135 | + | public static int add(int a, int b) { | |
| 136 | + | return a + b; | |
| 137 | + | } | |
| 138 | + | } | |
| 139 | + | ``` | |
| 140 | + | ||
| 141 | + | These examples cover the fundamental concepts you'll need to start programming in Java. Remember to: | |
| 142 | + | - Save each class in a separate file with the same name as the class | |
| 143 | + | - Compile your code using `javac FileName.java` | |
| 144 | + | - Run your program using `java FileName` | |
| 145 | + | ||
| 146 | + | Practice with these examples and modify them to experiment with different values and behaviors. This hands-on experience will help solidify your understanding of Java basics. | |