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Data Types in Java

In Java, data types are used to specify the type of data that a variable can store. Java has two categories of data types: primitive data types and reference data types. Here's an overview:


Primitive Data Types:


1. Integer Types:

   - `byte`: 8-bit signed integer.

   - `short`: 16-bit signed integer.

   - `int`: 32-bit signed integer (most commonly used for integers).

   - `long`: 64-bit signed integer.



  •    byte b = 127;
  •    short s = 32767;
  •    int i = 2147483647;
  •    long l = 9223372036854775807L;  // Note: Long literals end with 'L' or 'l'.



2. Floating-Point Types:

   - `float`: 32-bit floating-point.

   - `double`: 64-bit floating-point (most commonly used for floating-point numbers).


  •    float f = 3.14f;   // Note: Float literals end with 'F' or 'f'.
  •    double d = 3.14159265359;



3. Character Type:

   - `char`: 16-bit Unicode character.

  •    char ch = 'A';


 4. Boolean Type:

   - `boolean`: Represents true or false.


  •    boolean flag = true;



Reference Data Types:


1. Object Types:

   - Java is an object-oriented language, and objects are instances of classes.

  •    String text = "Hello, Java!";



2. Array Types:

   - Arrays are collections of elements of the same type.


  •    int[] numbers = {1, 2, 3, 4, 5};


3. User-Defined Types:

   - Classes and interfaces created by the user.



   class Person {

       String name;

       int age;

   }


   Person person = new Person();
   person.name = "John";
   person.age = 25;



Type Casting:


1. Implicit Casting:

   - Smaller data types can be implicitly cast to larger ones.


   int intValue = 10;

   long longValue = intValue;  // Implicit casting from int to long.


2. Explicit Casting:

   - Larger data types need explicit casting to smaller ones.


   double doubleValue = 3.14;

   int intValue = (int) doubleValue;  // Explicit casting from double to int.


Understanding and appropriately using data types is crucial for writing efficient and error-free Java programs. It helps in managing memory, ensuring data accuracy, and optimizing program performance.

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