Primitive Data Types

Variables

A variable in code is a kind of cell where we can store information. For example, if we need to save the number 20, we will save it in a variable and use this number again simply by using the variable name in the code.

Java is a strongly typed language, so we are required to define the data type of our variable:

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variable_type name = value;

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

Note
Note that the String data type is not a primitive data type, so we won't cover it in this section. It has a separate section where you will learn about this data type in detail.

Let's go through primitive data types and learn more about each of them:

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;

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 byte var = 10;

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;

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short var = 10000;

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;

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int var = 123123123;

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;

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long var = -10290394;

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;;

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float var = 13.41f;

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;

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double var = 12.299384;

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;

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boolean var = true;

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.

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char var = 'c';

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:

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package com.example;

public class Main {
    public static void main(String[] args) {
        int number = 41;
        System.out.println(number);
    }
}

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

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package com.example;

public class Main {
    public static void main(String[] args) {
        char character = 'c';
        System.out.println(character);
    }
}

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

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package com.example;

public class Main {
    public static void main(String[] args) {
        float number = 1.12f;
        System.out.println(number);
    }
}

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().

1. Which integer data type occupies the least amount of memory?

2. What data type can have only two values: ``true`` or ``false``?

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 1

Java Basics

Primitive Data Types

Variables

Data Types