# Java Language Basics
## Syntax
Java syntax is similar to C and C++. It uses semicolons to end statements and curly braces `{}` to define blocks of code.
## Printing in Java
Printing output in Java is typically done using `System.out.println()` or `System.out.print()` methods.
```java
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
```
## Variables in Java
Java variables must be declared with a specific type. Common types include `int`, `double`, `boolean`, `String`, etc.
```java
int age = 25;
double price = 19.99;
boolean isActive = true;
String name = "John";
```
## Loops
Java supports `for`, `while`, and `do-while` loops.
```java
// For loop
for (int i = 1; i <= 5; i++) {
System.out.println(i);
}
// While loop
int count = 1;
while (count <= 5) {
System.out.println(count);
count++;
}
// Do-while loop
int num = 1;
do {
System.out.println(num);
num++;
} while (num <= 5);
```
## Functions (Methods)
Functions in Java are called methods. They are defined within classes and can be `static` (class-level) or instance methods
```java
public class MyClass {
// Static method
public static void sayHello() {
System.out.println("Hello, World!");
}
// Instance method
public void greet(String name) {
System.out.println("Hello, " + name);
}
public static void main(String[] args) {
sayHello(); // Calling a static method
MyClass obj = new MyClass();
obj.greet("John"); // Calling an instance method
}
}
```
## Returning Values
Methods in Java can return values using the `return` keyword.
```java
public class Calculator {
public int add(int a, int b) {
return a + b;
}
public static void main(String[] args) {
Calculator calc = new Calculator();
int result = calc.add(5, 3);
System.out.println("Sum: " + result);
}
}
```
## Use of Lists (Arrays and ArrayLists)
Java arrays are fixed-size collections of elements of the same type. ArrayLists are dynamically resizable lists.
```java
// Arrays
int[] numbers = {1, 2, 3, 4, 5};
System.out.println("First number: " + numbers[0]);
// ArrayLists
import java.util.ArrayList;
ArrayList names = new ArrayList<>();
names.add("Alice");
names.add("Bob");
System.out.println("First name: " + names.get(0));
```