Firstly, we need to understand how to declare a variable in our code. It follows the syntax below:

The code above illustrates the basic syntax for declaring a variable.

Now, let's proceed to the study of data types, beginning with the 8 primary ones.

Data Types

• byte - This integer data type can accept values ranging from -128 to 127. It occupies 1 byte of memory and is stored in the stack memory;

• short - is also an integer data type that can hold values ranging from -32,768 to 32,767. It occupies 2 bytes of memory and is stored in the stack memory;

• int - This is the most commonly used integer data type, capable of holding values ranging from -2,147,483,648 to 2,147,483,647. It is also stored in the stack memory and occupies 4 bytes;

• long - This is the largest integer data type, capable of storing values from -2⁶³ to 2⁶³ - 1. It occupies 8 bytes in memory and is also stored in the stack memory;

• float - is the first floating-point data type to store 7 decimal digits. When declaring a variable of type float, we must remember to append the letter f at the end of the number. For example, float myFloat = 4.13f;;

• double - This floating-point data type can store up to 15 decimal digits. Unlike float, we don't need to specify letters when declaring a double variable. Double occupies 8 bytes and is stored in the stack memory;

• boolean - This primitive data type is special as it can only hold true or false values. Boolean is stored in the stack memory and occupies from 1 bit to 1 byte, depending on the system and compiler;

• char - This character data type takes data from the ASCII table. We will delve into this data type in more detail in the next chapter, but for now, please note that it occupies 2 bytes.

There is also a table where you can view all the essential information about primitive data types:

Primitive data types can also be output using the console output command. Let's examine some examples:

We declared an int variable and printed it on the screen.

We declared a char variable and printed it on the screen.

We declared a float variable and printed it on the screen.

Note

We don't need to wrap variables in double quotation marks as we did when outputting text using System.out.println().