Data Types

Data Types

• Data Type is used to store different types of values in variables.
• Example
• int myNum = 5;               // Integer (whole number)
• float myFloatNum = 5.99f;    // Floating point number
• char myLetter = 'D';         // Character
• boolean myBool = true;       // Boolean
• String myText = "Hello";     // String
• Data types are divided into two groups:

1. Primitive data types - includes byte, short, int, long, float, double, boolean and char
2. Non-primitive data types - such as String, Arrays and Classes.

Primitive Data Types

• A primitive data type specifies the size and type of variable values, and it has no additional methods.
• Numbers
• Primitive number types are divided into two groups:
• (a) Integer types stores whole numbers, positive or negative (such as 123 or -456), without decimals.
• Example: byte, short, int and long.
• (b) Floating-point types represents numbers with a fractional part, containing one or more decimals.
• Example: float and double.
• 1. Byte:
• Syntax: byte variable_name;
• Example: byte myNum = 100;
• System.out.println(myNum);
• Characteristics:
• Size: 1 byte
• Capacity: Stores whole numbers from -128 to 127
• 2. Short:
• Syntax: short variable_name;
• Example: short myNum = 5000;
• Syste.out.println(myNum);
• Charateristics:
• Size: 2byte
• Capacity: Stores whole numbers from -32,768 to 32,767
• 3. Int:
• Syntax: int variable_name;
• Example: int myNum = 100000;
• System.out.println(myNum);
• Characteristics:
• Size: 4 byte
• Capacity: Stores whole numbers from -2,147,483,648 to 2,147,483,647
• 4. Long:
• Syntax: long variable_name;
• Example: long myNum = 15000000000L;
• System.out.println(myNum);
• Characteristics:
• Define: It is write at end the value with an "L":
• Size: 8 byte
• Capacity: Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
• 5. Float:
• Syntax: float variable_name;
• Example: float myNum = 5.75f;
• System.out.println(myNum);
• Characteristics:
• Define: It is write at end the value with an "f":
• Size: 4 byte
• Capacity: Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits
• 6. Double:
• Syntax: double variable_name;
• Example: double myNum = 19.99d;
• System.out.println(myNum);
• Characteristics:
• Define: It is write at the end the value with a "d":
• Size: 8 byte
• Capacity: Stores fractional numbers. Sufficient for storing 15 decimal digits
• 7. Boolean:
• Syntax: boolean variable_name;
• Example: boolean bl = True;
• System.out.println(bl);
• Characteristics:
• Size: 1 bit
• Capacity: Stores true or false values
• 8. Char:
• Syntax: char variable_name;
• Example: char c;
• Characteristics:
• Define:
• The character must be surrounded by single quotes, like 'A' or 'C' or 'S':
• You can use ASCII values to display certain characters. such as a=65 or b=66
• Size: 2 byte
• Capacity: Stores a single character/letter or ASCII values

Non-Primitive Data Types

• String:
• Strings are used for storing text.
• A String variable contains a collection of characters surrounded by double-quotes.
• Syntax: String variable_name = "value";
• Example: String greeting = "Hello";
• Array:
• Arrays are used to store multiple values in a single variable, instead of declaring separate variables for each value.
• To declare an array, define the variable type with square brackets:
• Syntax: datatype variable_name[];
• Syntax: datatype []variable_name;
• Example: int age[];
• Example: int []age;
• Class:
• Everything in Java is associated with classes and objects.
• A Class is like an object constructor or a "blueprint" for creating objects.
• To create a class, use the keyword class.
• Syntax:
• public class Class_name {
• }
• Example:
• public class MyClass {
• }

Difference between Primitive and Non-primitive:

• Primitive types are predefined (already defined) in Java.
• Non-primitive types are created by the programmer and is not defined by Java (except for String).
• non-primitive types can be used to call methods to perform certain operations, while primitive types cannot.
• A primitive type has always a value, while non-primitive types can be null.
• A primitive type starts with a lowercase letter, while non-primitive types start with an uppercase letter.
• The size of a primitive type depends on the data type, while non-primitive types have all the same size