**Course Title:** Comprehensive Java Programming: From Basics to Advanced Concepts **Section Title:** Java Data Types and Operators **Topic:** Type Casting and Type Conversion In this topic, we will explore the concepts of type casting and type conversion in Java, which are essential for working with different data types. We will discuss the types of type casting, rules for type casting, and examples to illustrate each concept. ### 1. Introduction to Type Casting Type casting is the process of converting a value of one data type to another data type. It is a way to tell the compiler to treat a value of one type as if it were of another type. Type casting is important because it allows us to perform operations that would otherwise be invalid. ### 2. Types of Type Casting There are two types of type casting in Java: * **Widening Type Casting**: This type of casting involves converting a smaller data type to a larger data type. It is done automatically by the compiler and is also known as implicit type casting. ```java int x = 10; double y = x; // Implicit type casting ``` * **Narrowing Type Casting**: This type of casting involves converting a larger data type to a smaller data type. It needs to be done explicitly by the programmer and is also known as explicit type casting. ```java double x = 10.5; int y = (int) x; // Explicit type casting ``` ### 3. Rules for Type Casting Here are the rules for type casting in Java: * **Primitive to Primitive**: You can cast primitive types to other primitive types, as long as the target type is either the same or larger than the source type. * **Object to Object**: You can cast an object to its subclass type or to an interface that the object implements. * **Primitive to Object**: You can cast a primitive type to its corresponding wrapper class type. * **Object to Primitive**: You can cast an object of a wrapper class to its corresponding primitive type. ### 4. Example: Type Casting with Primitive Types Here is an example that demonstrates type casting with primitive types: ```java public class TypeCastingExample { public static void main(String[] args) { int x = 10; double y = x; // Implicit type casting System.out.println("y = " + y); int z = (int) y; // Explicit type casting System.out.println("z = " + z); } } ``` In this example, we first implicitly cast an `int` to a `double`. Then, we explicitly cast the `double` back to an `int`. Note that during narrowing type casting, we may lose some precision. ### 5. Example: Type Casting with Objects Here is an example that demonstrates type casting with objects: ```java public class Animal { public void sound() { System.out.println("The animal makes a sound."); } } public class Dog extends Animal { public void bark() { System.out.println("The dog barks."); } } public class TypeCastingExample { public static void main(String[] args) { Animal a = new Dog(); Dog d = (Dog) a; // Explicit type casting a.sound(); d.sound(); d.bark(); } } ``` In this example, we create a `Dog` object and upcast it to an `Animal`. We can call the `sound()` method on the `Animal` reference. Then, we downcast the `Animal` to a `Dog` and call the `bark()` method on the `Dog` reference. ### 6. Practice Exercises 1. Write a Java program that performs implicit and explicit type casting between `int` and `double`. 2. Write a Java program that demonstrates type casting with objects. Create a base class and a subclass, and then cast the subclass to the base class. ### Additional Reading: * Oracle's Java Tutorials: [Type Casting](https://docs.oracle.com/javase/tutorial/java/IandI/casting.html) * Java API Documentation: [Primitive Types](https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html) * Stack Overflow: [Type Casting in Java](https://stackoverflow.com/questions/5289393/casting-variables-in-java) ### Share Your Feedback: If you have any questions or need help with a specific topic, feel free to leave a comment below. ### Next Topic: In the next topic, we will discuss conditional statements: if-else, switch-case. Note: Please make sure to ask any questions related to the topic in the comments below.