There are many situations that come when we have to change the functionality of the output as well as the type of output according to the need of the requirements. For e.g. Entered PI value in decimal format should be converted in the decimal format so that value can be used efficiently without any kind of errors and wrong output.
There are two ways we can change the type from one to another.
- Type casting
- Type conversion
Type Casting means to change one state to another state and is done by the programmer using the cast operator. Type Casting is done during the program design time by the programmer. Typecasting also refers to Narrow Conversion. Because in many cases, We have to Cast large datatype values into smaller datatype values according to the requirement of the operations. We can also convert large datatype values into smaller datatype values that’s why Type Casting called Narrow Casting.
Syntax: () is Cast Operator
RequiredDatatype=(TargetType)Variable
Example 1:
Java
// Java Program to Implement Type Casting of the DatatypeÂ
// Importing input output classesimport java.io.*;Â
// Main classpublic class GFG {Â
    // Main driver method    public static void main(String[] args)    {        // Declaring an Integer datatype        int a = 3;Â
        // Casting to Large datatype        double db = (double)a;Â
        // Print and display the casted value        System.out.println(db);Â
        // Narrow Casting conversion        int db1 = (int)db;                 // Print an display narrow casted value        System.out.println(db1);    }} |
3.0 3
Type Conversion is a type conversion that is done by compiler done by a compiler without the intention of the programmer during the compile time. This Conversion sometimes creates an error or incorrect answer if the proper resultant data type does not mention at the end of the multiple expression of the datatype that’s why Type Conversion is less efficient than Type Casting.
The working mechanism of type conversion is as follows:
double > float > long > int > short > byte
Example 1: Error during type conversion
Java
// Java Program to illustrate Type ConversionÂ
// Importing input output classesimport java.io.*;Â
// Main classpublic class GFG {Â
    // Main driver method    public static void main(String[] args)    {        // Declaring and initializing variables to values        // with different return type        long a = 3;        byte b = 2;        double c = 2.0;Â
        // Type Conversion        int final_datatype = (a + b + c);Â
        // Print statement        System.out.print(final_datatype);    }} |
Output:
prog.java:9: error: incompatible types: possible lossy conversion from double to int
int final_datatype = (a + b + c);
^
1 error
Output explanation:
When you assign the value of one data type to another, the two types might not be compatible with each other. If the data types are compatible, then Java will perform the conversion automatically known as Automatic Type Conversion, and if not then they need to be cast or converted explicitly. For example, assigning an int value to a long variable.
Example 2:
Java
// Java Program to illustrate Type ConversionÂ
// Importing input output classesimport java.io.*;Â
// Main Classclass GFG {Â
    // Main driver method    public static void main(String[] args)    {        // Declaring and initializing variables to values        // but to different data types        long a = 3;        byte b = 2;        double c = 2.0;Â
        // Type Conversion        // As long and byte data types are converted to        // double return type        double final_datatype = (a + b + c);Â
        // Printing the sum of all three initialized values        System.out.print(final_datatype);    }} |
7.0
