Java Tutorial - Variables and Concatenation

A variable is a named memory location that stores a value of a particular data type. Variables are used to store data that can be used in your program's operations, calculations, and decision making.

A variable has a name, a data type, and a value. The name is used to refer to the variable in the code. The data type defines the type of value that the variable can hold, such as an integer, a floating-point number, or a string. The value is the actual data that is stored in the variable.

Concatenation in programming refers to the operation of combining two or more strings or values into a single string or value. In most programming languages, concatenation is performed using a concatenation operator, which is typically the plus sign (+).

In Java, the concatenation operator is the plus sign (+). When you use the plus sign to concatenate two or more strings, Java will combine them into a single string.

A string is a sequence of characters that represents text. Strings are used to store and manipulate textual data in Java programs.

public class Main {

	public static void main(String[] args) {
		int width = 30;
		int height = 3;
		
		int area = width * height;		
		
		System.out.println("Custom Explanation: " + "---> " + area + " Something More");
		
		final int voltage = 13;		
		
		System.out.println(voltage);
		
	}	
}

Here's an explanation of each line of code: 

public class Main {

This line declares a public class named "Main". This is the entry point of the program. 

public static void main(String[] args) {

This line declares a public static method named "main" that takes an array of strings as its argument. This is the method that is called when the program runs. 

int width = 30;

This line declares an integer variable named "width" and initializes it with the value of 30. 

int height = 3;

This line declares an integer variable named "height" and initializes it with the value of 3. 

int area = width * height;

This line declares an integer variable named "area" and initializes it with the product of "width" and "height". 

System.out.println("Custom Explanation: " + "---> " + area + " Something More");

This line prints a message to the console that includes the value of "area". The message includes the string "Custom Explanation: ", followed by the value of "area", followed by the string " Something More". 

final int voltage = 13;

This line declares a final integer variable named "voltage" and initializes it with the value of 13. The "final" keyword means that the value of "voltage" cannot be changed later in the program. 

System.out.println(voltage);

This line prints the value of "voltage" to the console.