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Comparison between typecasting and boxing/unboxing in Java:

	Typecasting	Boxing/Unboxing
Definition	Converting a value of one data type to another data type	Converting a primitive data type to an object and vice versa
Syntax	(target_type) value	Object obj = value; or target_type value = (target_type) obj;
Example	int x = (int) 3.14;	Integer y = new Integer(3); or int z = y.intValue();
Performance	Faster	Slower
Use	When you need to convert a value of one data type to another data type and you are sure that the conversion will be successful	When you need to use a primitive data type as an object, for example, to store it in a collection

💡Definitions

-Assigning a value of one type to a variable of another type is known as Type Casting.

💡Datatype hierarchy-

(Biggest datatype) double > float > long > int > char > short > byte (smallest datatype)

Comparison between auto typecasting and manual typecasting in Java:–

	Auto Typecasting	Manual Typecasting
Definition	Implicit conversion of a value from one data type to another	Explicit conversion of a value from one data type to another
Syntax	No special syntax required	(target_type) value
Example	int x = 3.14;	int x = (int) 3.14;
Performance	Faster	Faster
Use	When the target data type is large enough to hold the value being converted	When you need to explicitly control the type of the value being converted, or when the target data type is not large enough to hold the value being converted

💡(i)Widening/Automatic type conversion/Up casting

-When value of small datatype is saved into big datatype.
i.e-
int i=10;
double d=i;

💡(ii)Narrowing/manual type conversion/down casting

-When value of big datatype is saved into small datatype.
i.e- double d=455.3d;
int i=(int)d;

Code samples are here

1-Program to perform upcasting and downcasting

package typecasting6;
public class Typscting {

public static void main(String[] args) {
//upcasting
int a1=20; //from int
double b=a1; //to double
System.out.println("Upcasting from int to double = "+b);

//downcasting
double x=10.0d; //from double
int c=(int)x; //to int
System.out.println("Downcasting from double to int = "+c);
}
}

Run this Program ▶️

💡Boxing/InBoxing and OutBoxing-

Comparison between boxing and unboxing in Java:-

	Boxing	Unboxing
Definition	Converting a primitive data type to an object	Converting an object to a primitive data type
Syntax	Object obj = value;	target_type value = (target_type) obj;
Example	Integer y = new Integer(3);	int z = y.intValue();
Performance	Slower	Slower
Use	When you need to use a primitive data type as an object, for example, to store it in a collection	When you need to use the value of an object as a primitive data type

Boxing

💡(i) Boxing/InBoxing

– Conversion of primitive into non primitive
i.e – int i=10;
Integer i1=i; // Integer is a class so i1 is a object(non primitive)

💡(ii) OutBoxing

– Conversion of non primitive into primitive
i.e Integer i=10;
int i1=i;

code samples are here

2-Program to perform boxing and outboxing

package boxingNunboxing7;
public class BoxngUnboxing {

public static void main(String[] args) {

//boxing
int x=10; //from primitive(x)
Integer c=x; //to non primitive(b)
System.out.println(c);

//out boxing
Integer a1=20; //from non primitive(a1)
int b=a1; //to primitive(b)
System.out.println(b);
}
}

Run this Program ▶️

Questions set —

• What is difference between automatic type conversion and manual type conversion?
• What is difference between inboxing and outboxing?