Data Types in Java

Data types specify the different sizes and values that can be stored in the variable. There are two types of data types in Java:

1. Primitive data types: The primitive data types include boolean, char, byte, short, int, long, float and double.
2. Non-primitive data types: The non-primitive data types include Classes, Interfaces, and Arrays.

Let's understand in detail about the two major data types of Java in the following paragraphs.

Java Primitive Data Types

In Java language, primitive data types are the building blocks of data manipulation. These are the most basic data types available in Java language.

Java is a statically-typed programming language. It means, all variables must be declared before its use. That is why we need to declare variable's type and name.

In Java, there are mainly eight primitive data types and let's understand about them in detail in the following paragraphs.

Java Primitive data types:

1. boolean data type
2. byte data type
3. char data type
4. short data type
5. int data type
6. long data type
7. float data type
8. double data type

Boolean Data Type

In Java, the boolean data type represents a single bit of information with two possible states: true or false. It is used to store the result of logical expressions or conditions. Unlike other primitive data types like int or double, boolean does not have a specific size or range. It is typically implemented as a single bit, although the exact implementation may vary across platforms.

Example:

One key feature of the boolean data type is its use in controlling program flow. It is commonly employed in conditional statements such as if, while, and for loops to determine the execution path based on the evaluation of a boolean expression. For instance, an if statement executes a block of code if the boolean expression evaluates to true, and skips it if the expression is false.

Byte Data Type

The byte data type in Java is a primitive data type that represents an 8-bit signed two's complement integer. It has a range of values from -128 to 127. Its default value is 0. The byte data type is commonly used when working with raw binary data or when memory conservation is a concern, as it occupies less memory than larger integer types like int or long.

Example:

One common use of the byte data type is in reading and writing binary data, such as files or network streams. Since binary data is often represented using bytes, the byte data type provides a convenient way to work with such data. Additionally, the byte data type is sometimes used in performance-critical applications where memory usage needs to be minimized.

Short Data Type

The short data type in Java is a primitive data type that represents a 16-bit signed two's complement integer. It has a range of values from -32,768 to 32,767. Similar to the byte data type, short is used when memory conservation is a concern, but more precision than byte is required. Its default value is 0.

Example:

In Java, short variables are declared using the short keyword. For example, short myShort = 1000; declares a short variable named myShort and initializes it with the value 1000. As with the byte data type, short variables must be explicitly cast when used in expressions with larger integer types to avoid loss of precision.

Int Data Type

The int data type in Java is a primitive data type that represents a 32-bit signed two's complement integer. It has a range of values from -2,147,483,648 to 2,147,483,647. The int data type is one of the most commonly used data types in Java and is typically used to store whole numbers without decimal points. Its default value is 0.

Example:

In Java, int variables are declared using the int keyword. For example, int myInt = 100; declares an int variable named myInt and initializes it with the value 100. int variables can be used in mathematical expressions, assigned to other int variables, and used in conditional statements.

Long Data Type

The long data type in Java is a primitive data type that represents a 64-bit signed two's complement integer. It has a wider range of values than int, ranging from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807. Its default value is 0.0F. The long data type is used when int is not large enough to hold the desired value, or when a larger range of integer values is needed.

Example:

The long data type is commonly used in applications where large integer values are required, such as in scientific computations, financial applications, and systems programming. It provides greater precision and a larger range than int, making it suitable for scenarios where int is insufficient.

Float Data Type

The float data type in Java is a primitive data type that represents single-precision 32-bit IEEE 754 floating-point numbers. It can represent a wide range of decimal values, but it is not suitable for precise values such as currency. The float data type is useful for applications where a higher range of values is needed, and precision is not critical.

Example:

One of the key characteristics of the float data type is its ability to represent a wide range of values, both positive and negative, including very small and very large values. However, due to its limited precision (approximately 6-7 significant decimal digits), it is not suitable for applications where exact decimal values are required.

Double Data Type

The double data type in Java is a primitive data type that represents double-precision 64-bit IEEE 754 floating-point numbers. Its default value is 0.0d. It provides a wider range of values and greater precision compared to the float data type, making it suitable for applications where accurate representation of decimal values is required.

Example:

One of the key advantages of the double data type is its ability to represent a wider range of values with greater precision compared to float. It can accurately represent values with up to approximately 15-16 significant decimal digits, making it suitable for applications that require high precision, such as financial calculations, scientific computations, and graphics programming.

Char Data Type

The char data type in Java is a primitive data type that represents a single 16-bit Unicode character. It can store any character from the Unicode character set, that allows Java to support internationalization and representation of characters from various languages and writing systems.

Example:

The char data type is commonly used to represent characters, such as letters, digits, and symbols, in Java programs. It can also be used to perform arithmetic operations, as the Unicode values of characters can be treated as integers. For example, you can perform addition or subtraction operations on char variables to manipulate their Unicode values.

Non-Primitive Data Types in Java

In Java, non-primitive data types, also known as reference data types, are used to store complex objects rather than simple values. Unlike primitive data types that store the actual values, reference data types store references or memory addresses that point to the location of the object in memory. This distinction is important because it affects how these data types are stored, passed, and manipulated in Java programs.

Class

One common non-primitive data type in Java is the class. Classes are used to create objects, which are instances of the class. A class defines the properties and behaviors of objects, including variables (fields) and methods. For example, you might create a Person class to represent a person, with variables for the person's name, age, and address, and methods to set and get these values.

Interface

Interfaces are another important non-primitive data type in Java. An interface defines a contract for what a class implementing the interface must provide, without specifying how it should be implemented. Interfaces are used to achieve abstraction and multiple inheritance in Java, allowing classes to be more flexible and reusable.

Arrays

Arrays are a fundamental non-primitive data type in Java that allow you to store multiple values of the same type in a single variable. Arrays have a fixed size, which is specified when the array is created, and can be accessed using an index. Arrays are commonly used to store lists of values or to represent matrices and other multi-dimensional data structures.

Enum

Java also includes other non-primitive data types, such as enums and collections. Enums are used to define a set of named constants, providing a way to represent a fixed set of values. Collections are a framework of classes and interfaces that provide dynamic data structures such as lists, sets, and maps, which can grow or shrink in size as needed.

Overall, non-primitive data types in Java are essential for creating complex and flexible programs. They allow you to create and manipulate objects, define relationships between objects, and represent complex data structures. By understanding how to use non-primitive data types effectively, you can write more efficient and maintainable Java code.

Why char uses 2 byte in Java and what is \u0000 ?

It is because Java uses Unicode system not ASCII code system. The \u0000 is the lowest range of Unicode system. To get detail explanation about Unicode visit next page.