
public class HelloWorld {	// class
	
	public static int value = 89;

	public static void main(String[] args) {	// method

		// single-line comment
		// this line will display Hello World!
		System.out.println("Hello World!");

		/*
		 * this is a multiple-line commen
		 * if you have a long descriptions, 
		 * use this comment
		 */
		System.out.println("Welcome to Java Programming.");
		
		/**
		 * this is javadoc
		 */
		
		// declare primitive data types variables
		int num = 8;				// default type
		System.out.println(num);
		
		long bigNum = 9L;
		System.out.println(bigNum);
		
		double unitPrice = 19.99;	// default type
		float totalPrice = 29.99F;
		System.out.println(unitPrice);
		System.out.println(totalPrice);
		
		// use + concatenator operator
		System.out.println("Unit Price: " + unitPrice);
		
		char color = 'G';	// single-quote to define char
		System.out.println(color);
		
		boolean flag = true;
		System.out.println(flag);
		
		System.out.println("Value: " + value);
		
		test();	// call the method
	}
	
	// define another method that try to access variables defined in main
	public static void test() {
//		System.out.println("Unit Price: " + unitPrice);
		System.out.println("Value: " + value);
		
		// increment
		value++;	// value = value + 1
		System.out.println("Value: " + value);
		
	}

}
