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Java Syntax Guide

Java is a class-based, object-oriented programming language. Here are the basic syntax rules:

All code must be inside a class
Class names should start with an uppercase letter
Method names should start with a lowercase letter
Curly braces {} define the beginning and ending of a block of code
Semicolons ; terminate statements
Java is case-sensitive

Basic Structure:

public class ClassName {
   public static void main(String[] args) {
       // Your code here
   }
}

Java Basics

Data Types

Type	Description	Example
int	Integer numbers	int age = 25;
double	Decimal numbers	double price = 19.99;
boolean	True/false values	boolean isActive = true;
String	Text values	String name = "John";

Common Operators

Arithmetic: +, -, *, /, %
Comparison: ==, !=, <, >, <=, >=
Logical: &&, ||, !

Common Code Examples

Variables and Data Types

int number = 10;
double decimal = 3.14;
boolean isTrue = false;
String text = "Hello, World!";

System.out.println(number);
System.out.println(decimal);
System.out.println(isTrue);
System.out.println(text);

Conditional Statements

int age = 18;
if (age >= 18) {
   System.out.println("Adult");
} else {
   System.out.println("Minor");
}

Loops

// For loop
for (int i = 0; i < 5; i++) {
   System.out.println("Count: " + i);
}

// While loop
int j = 0;
while (j < 5) {
   System.out.println("While: " + j);
   j++;
}

Useful Code Snippets

Hello World

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

Simple Calculator

import java.util.Scanner;

public class Calculator {
   public static void main(String[] args) {
       Scanner scanner = new Scanner(System.in);
       
       System.out.print("Enter first number: ");
       double num1 = scanner.nextDouble();
       
       System.out.print("Enter second number: ");
       double num2 = scanner.nextDouble();
       
       System.out.println("Sum: " + (num1 + num2));
       System.out.println("Difference: " + (num1 - num2));
       System.out.println("Product: " + (num1 * num2));
       System.out.println("Quotient: " + (num1 / num2));
       
       scanner.close();
   }
}

Array Example

public class ArrayExample {
   public static void main(String[] args) {
       // Create an array of integers
       int[] numbers = {10, 20, 30, 40, 50};
       
       // Print all elements
       for (int i = 0; i < numbers.length; i++) {
           System.out.println("Element at index " + i + ": " + numbers[i]);
       }
   }
}

Debugging Tips

Common Errors and Solutions

Semicolon expected: Forgot to add ; at the end of a statement
Cannot find symbol: Misspelled a variable or method name
Class names must start with uppercase: Naming convention violation
Reached end of file while parsing: Missing closing brace }
Exception in thread "main": Runtime error, often caused by invalid operations

Debugging Techniques

Read the error message carefully
Check line numbers mentioned in error
Use System.out.println() to print variable values
Verify all braces are properly matched
Ensure all statements end with semicolons
Check for typos in variable/method names

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Java Coding Help

Java Syntax Guide

Basic Structure:

Java Basics

Data Types

Common Operators

Common Code Examples

Variables and Data Types

Conditional Statements

Loops

Useful Code Snippets

Hello World

Simple Calculator

Array Example

Debugging Tips

Common Errors and Solutions

Debugging Techniques

Additional Resources

Practice Platforms