#8 Type Conversion in Java

Summary

This video script delves into the intricacies of data types, type conversion, and casting in programming. It explains that variables are immutable in their type but can be assigned values of different types, leading to implicit or explicit conversions. The script uses byte and integer types to illustrate how data can be lost during narrowing conversions and how widening conversions are allowed. It also introduces the concept of casting, where data types are explicitly converted, and type promotion, where operations on smaller data types are automatically promoted to larger types to prevent data loss. The tutorial is practical, guiding viewers through code examples and the impact of these concepts in programming.

Takeaways

• 😀 Variables in programming must have a name and a type, such as int, float, double, char, boolean, and string.
• 🔄 You cannot change the type of a variable once it's declared, but you can assign values of different types to it, depending on compatibility.
• ❌ Assigning a value from a larger data type (like int) to a smaller one (like byte) without explicit conversion will result in a compilation error.
• ✅ Implicit conversion (widening) is allowed when assigning a smaller data type value to a larger one, as the larger type can accommodate the smaller one.
• ⚙️ Explicit conversion (narrowing) is done through casting, where you manually convert a value from one type to another, potentially losing data if the target type has a smaller range.
• 🚫 Not all types can be implicitly or explicitly converted, such as assigning a character value to a boolean, due to their incompatible nature.
• 📉 When converting from float to int, the decimal part of the float is truncated, and only the integer part is retained.
• 🔀 Type promotion occurs automatically during operations when the result exceeds the range of the original data type, such as multiplying two byte values that exceed the byte range, and the result is promoted to an int.
• 💡 Understanding type conversion and casting is crucial for more advanced programming concepts, including object-oriented programming (OOPs).
• 💻 The video script provides a practical guide on how to handle different data types and perform conversions in Java, with examples and potential pitfalls.

Q & A

What are the two essential characteristics of a variable?

Every variable needs a name and a type.

What is the range of values that a byte variable can hold?

A byte variable can hold values from -128 to 127.

Can you change the type of a variable in Java?

No, you cannot change the type of a variable in Java, but you can assign values of different types to variables through type conversion or casting.

What is the difference between type conversion and type casting?

Type conversion is an automatic process where the type of a value is changed implicitly, while type casting is an explicit process where you manually convert a value from one type to another using a cast.

What happens when you assign a value that is outside the range of a byte variable?

When assigning a value outside the range of a byte variable, Java uses the modulus operator to find the remainder of the division of the value by 256, effectively wrapping around the byte's range.

Why can't you assign an integer value directly to a byte variable if it's outside the byte's range?

Assigning an integer value directly to a byte variable that is outside the byte's range will result in a loss of data and is not allowed because it can cause overflow or underflow, leading to incorrect values.

How do you convert an integer value to a byte in Java?

You can convert an integer value to a byte in Java by explicitly casting the integer value to a byte using the syntax `(byte)integerValue`.

What is the result of converting a floating-point number to an integer in Java?

When converting a floating-point number to an integer in Java, the decimal part of the number is truncated, and only the integer part is retained.

What is type promotion?

Type promotion is the automatic conversion of a smaller data type to a larger one during arithmetic operations to prevent data loss. For example, when multiplying two byte values that result in a number exceeding the byte range, Java promotes the operation to use integer arithmetic.

How can you perform arithmetic operations involving different data types without causing errors?

To perform arithmetic operations involving different data types without causing errors, you can use type casting to convert the smaller data type to a larger one before the operation, ensuring that the result fits within the range of the larger type.

Outlines

00:00

🔢 Understanding Variable Types and Casting

This paragraph introduces the concept of variable types in programming, emphasizing that every variable has a name and a type. It discusses the different data types available for storing various kinds of data, such as integers, characters, Booleans, and strings. The speaker then addresses the question of whether the type of a variable can be changed, explaining that it cannot. However, assigning values of one type to a variable of another type is possible, with certain limitations. The concept of type casting is introduced as a way to explicitly convert one data type to another. The paragraph explains the difference between implicit and explicit conversions, using examples of assigning integer values to byte variables and vice versa. The importance of being aware of data type ranges and the potential for data loss during explicit conversions is highlighted.

05:02

📊 Exploring Data Type Ranges and Conversions

The second paragraph delves deeper into the practical implications of data type ranges and conversions. It uses the example of assigning integer values to a byte variable, illustrating how values that exceed the byte's maximum capacity result in a modulo operation, effectively wrapping around the value within the byte's range. The paragraph also discusses the use of Java's single-step compilation and execution command for learning purposes, contrasting it with the standard two-step process. It provides a hands-on example of how to assign and print byte values, and how to handle incompatible types by using type casting. The paragraph concludes with a demonstration of how assigning an integer value outside the byte range results in a modulo operation, which is a form of automatic type conversion to fit within the data type's constraints.

10:03

🌐 Advanced Type Conversions and Type Promotion

The final paragraph explores advanced type conversions, particularly focusing on the conversion between floating-point and integer types. It explains the loss of decimal precision when converting from a float to an int, as the decimal part is truncated. The concept of type promotion is introduced, where operations on smaller data types are automatically promoted to a larger type to prevent data loss. An example is given where a multiplication of two byte values results in a number that exceeds the byte range, prompting Java to promote the result to an integer. The paragraph concludes with a demonstration of these concepts through code examples, emphasizing the importance of understanding type conversions and promotions in programming, especially when working with object-oriented programming concepts.

Keywords

💡Type

In the context of the video, 'type' refers to the data type of a variable in programming, which determines the kind of data it can hold. For instance, an integer type variable can hold whole numbers, while a float type can hold decimal numbers. The video emphasizes that every variable needs a type, and understanding types is crucial for proper variable declaration and usage in programming.

💡Variable

A 'variable' in programming is a storage location paired with an associated symbolic name, which contains some known or unknown quantity of information referred to as a value. The video script discusses how variables need both a name and a type, and it uses variables to illustrate the concepts of type conversion and casting.

💡Type Conversion

Type conversion, as explained in the video, is the process of changing a value from one data type to another. It is a fundamental concept in programming that allows for flexibility in how data is handled. The video provides examples of implicit conversions, such as assigning a byte value to an integer variable, which automatically 'widens' the type to accommodate the value.

💡Type Casting

Type casting is a form of explicit type conversion where the programmer manually converts a value from one data type to another. The video illustrates this with the example of assigning an integer value to a byte variable, which requires casting because the integer might have a value that exceeds the byte's range. Casting is important for ensuring that data is handled correctly and for preventing data loss or errors.

💡Range

The 'range' of a data type refers to the set of values that the type can represent. In the video, the range of a byte is discussed as being from -128 to 127, which is crucial when assigning values to variables of this type. Understanding the range helps in determining whether a value can be safely assigned to a variable without causing an overflow or underflow.

💡Modulus Operator

The 'modulus operator' is used in programming to find the remainder of a division operation. The video explains how this operator is used when assigning a value to a byte variable that exceeds its range. The modulus operation with the range of the byte type (256) is performed to find the new value that fits within the allowable range.

💡Implicit Conversion

Implicit conversion, also known as automatic conversion, occurs when a programming language automatically converts one data type to another without the programmer explicitly requesting it. The video contrasts this with explicit casting, using the example of assigning a byte value to an integer variable, which is automatically widened to fit the larger range of the integer.

💡Data Loss

In the context of the video, 'data loss' refers to the loss of information that occurs when converting a value from a type with a higher precision or range to one with a lower precision or range. For example, assigning a float value to an integer variable results in the loss of the decimal part of the float. The video highlights the importance of being aware of potential data loss during type conversions.

💡Type Promotion

Type promotion is a form of implicit conversion where a smaller data type is automatically promoted to a larger one to accommodate the result of an operation. The video uses the example of multiplying two byte values, which would exceed the range of a byte, so the result is automatically promoted to an integer. This ensures that the operation does not result in overflow or loss of data.

💡Primitive Values

Primitive values are the basic data types provided by a programming language, such as integers, floats, and characters. The video discusses casting and conversion in the context of primitive values, explaining how these operations are necessary for managing data types and ensuring that data is stored and manipulated correctly.

Highlights

Variables require a name and a type.

Types include int, float, double, char, Boolean, and string.

Variables cannot change their type, but values can be assigned across different types.

Assigning a larger type value to a smaller type may result in data loss.

Implicit conversion occurs when a smaller type is assigned to a larger type variable.

Explicit conversion, known as casting, is used to convert a larger type to a smaller one.

Casting involves specifying the target type within parentheses before the variable name.

Automatic conversions are possible between certain numeric types but not between incompatible types like char and Boolean.

Type promotion occurs when an operation's result exceeds the range of the variable type, and it's automatically promoted to a larger type.

Demonstration of assigning an integer value to a byte variable and the resulting modulus operation.

Casting is important for future concepts like object-oriented programming.

Type conversion and casting are essential for handling different data types in programming.

The video provides a practical example of type conversion using Java code.

The concept of type promotion is illustrated with a multiplication operation between byte values.

The video explains the difference between automatic conversion and explicit casting.

A shortcut for compiling and running Java code in a single step is introduced for learning purposes.

The video concludes with a summary of the key points about type conversion and casting.

Transcripts

in this video we'll talk about type

conversion and type casting so in the

previous video we have talked about

variables how to create a variable and

then one thing is for sure in fact two

things every variable needs a name so we

have talked about it and every variable

needs a type as well so if you want to

get a variable for numbers you will say

ain't float double or long in fact we

have sub tabs as as well for INT and

then if you want to store a character we

can use CAD if you want to store a

Boolean value we have Boolean option and

then we also have a string which we'll

talk about that later at this point we

have a lot of different types now there

is one confusion what if you want to

change the type of a variable uh can we

really do that so unfortunately we can't

we can't change the type of a variable

but then can you assign a value to other

type example let's say we have a

variable which is of type byte so I'm

using a byte variable which is B and it

will have a value now of course we have

talked about a range of byte as well you

can have maximum 120 is 7 plus I mean

plus 2 127 this is the max value you can

accommodate here but can you assign a

integer value that's a question so what

if you have a variable of type int a and

the value of a is 256. now what will

happen if you try to assign this a value

which is 256 into B something like this

what if I say B is equal to a so what

I'm doing now is I'm assigning a value

of integer to byte now unfortunately

this will not work but what will work

the reverse will work what if you have a

variable which is a and then you are

trying to assign a value which is B this

will work so what happens is the type of

a is integer right it has a bigger range

and byte has a small range so your

compiler says hey you're trying to

assign a integer value to byte and at

this point you will lose you might lose

some data so basically we are trying to

convert it and it is narrowing it right

so we are narrowing the size of it on

the other hand if we talk about this

operation here we are widening it

because this the range of byte is small

and integers a bigger one so of course

you can put a small items in a bigger

box but if you put a bigger item in a

small box it will not work right okay

cool so that makes sense right but then

what if you really want to do it you

want to convert a integer value into

byte see at this point if the value of a

is not 256 what is the value of a is

let's say 12. now the value of a is 12

which can be accommodated in b as well

so at this point even your compiler will

say hey I I don't know what your value

of a is but I will not allow you to

store the value of a in B because a is

integer and B is byte so in this case

you can say hey compiler give me one

second here what you can do is you can

say B is equal to you can convert a you

can do a conversion by saying you can

give a bracket and you can mention the

type in which type you want to convert

you can say byte and you can mention the

variable name a so what you're doing is

you're converting integer value into the

byte format okay now this concept is

called casting so basically this is

actually a conversion but explicitly

you're doing it so whenever you do

explicit conversion it is called casting

so when I say explicit there should be

implicit as well right and that is

correct we have some conversions which

are implicit example if you talk about

this particular operation here this is a

implicit conversion basically you're

trying to store a byte value into a

integer variable so it becomes an

integer when you assign it right so this

is a conversion okay so when you do it

explicitly that is casting when it is

opening if it is happening automatically

that is conversion now this makes sense

right now is it means you can do it with

anything uh not exactly there are

certain types example you can't store a

character value into a Boolean value

okay because Boolean only supposed to

end false and character supports all the

characters so you can't do those

conversions but anything in the range of

integer float double actually works

example uh we have talked about integer

and byte if it is long as well that

completely works now what if you have a

scenario where you want to store maybe

of type a float value now let's say you

have an integer variable here which is

int let's say x is equal to and you're

trying to assign a float value now float

value is let's say 5.6 of course I can

create a float variable I can assign

this value to that or maybe this is

double because we don't have F so let's

say this this is double and then you're

trying to assign that to integer now

what will happen is in this case if even

this will not work so what you have to

do is you have to apply you have to

convert it so what I will do now is let

me just create a float variable here so

I will say float f is equal to 5.6 and

remember you have to put F at the end

now if you try to put f it will not work

so what you do is you have to explicitly

convert this value into integer so what

you're doing is you're assigning a float

value to an integer so you're converting

it now what you will lose here so at

this point you will lose your point

values so whatever value you have in

after that point you will lose an

example the value of five point it is

5.6 so here when you convert that it

becomes five so in the X

the value you will be getting is only

five cool uh so it makes sense right so

for float it will cut the value but

coming back to byte now what will happen

when you talk about byte here what do

you think we don't have Point values so

if you have a bigger number uh example

let's say this is not one this is not 12

let's say we have a bigger number here

and the bigger number is let's say 257.

now what will happen when you assign 257

because the range ends at 127 you can't

go beyond that right so in this case it

will use a concept of modulus okay or

modular operator so what modular will do

is it will divide this number so

whenever I try to assign a integer value

to byte which which we are doing here so

when you're trying to assign a integer

value to a byte it will convert that

into modulo which is it will divide the

number a which is 257 and it will find

the percentage okay so 257 percentage

which is a modular symbol and it will

divide it with a range okay which is 2

of 256 because a complete range of byte

is 256 right from -128 to plus 127 and

then the remainder you will get here is

one cool so the answer here when you try

to do it with the 257 it will be one I

will show you that in the code so coming

back to the code let's try all this

operation which we talked about so what

we'll do is we'll start with a integer

value we can say or maybe we can start

with byte so we can say byte B is equal

to and maximum you can have is 127 let's

take that value and let's try to print

it here so we can say system dot out Dot

println and here let's print the value

of B so when you save that and when you

go back here when you write when you try

to run this so we say Java C and Hello

dot Java comparison done let's run this

code I can say Java space I have to run

with the class file which is hello and

you can see we got 127. now what will

happen if you're trying to do that with

257 it will not work first of all it

will say although you can see we got

data it says incompatible types because

it is integer type now 257 okay so we

can say 127 here now next what I'm going

to do is I want to create a integer

variable here which is int int n is

equal to and I can assign a value maybe

let's say a because we have used that so

we'll say a and then the value we are

going to assign is of B so can you

assign a byte value to integer because

this is this is where you're doing

converting and if you try to print the

value of a let's try that in fact

there's one more thing which is which

came recently in Java so basically you

know we always do two steps right first

you compile the code and then you run

the code right so you compile that with

the help of java C and when you compile

it you see you say Hello dot Java and

when you run it you say simply say Java

and hello you have to do two steps right

so when you're into learning phase why

to do two steps you can actually do in

single step again not recommended for a

big project or not even for a small

project don't you don't even try that in

your company for learning purpose we are

doing it so basically we got a shortcut

we can say Java space Hello dot Java

directly maybe it is getting influenced

by the other languages where you simply

mention the command and a file name no

need to mention compile and run Subway

step let's try this and you can say it

works so you can see we got 127 it is

perfectly working and just to show you

that things are happening behind the

scene the value is getting changed you

can see we got 125. so from now from

whenever you have single file will use

this but remember this is just a

shortcut ultimately behind the scene we

need to do this okay I mean when you

build a project first you have to

compile the code then run the code this

is a shortcut and one more thing this

will work only in the recent version of

java I guess from java 14 if you have an

older version of java this might not

work so if it's not working in your

machine that means you have an older

version upgrade your jdk version Okay

cool so now what I will do here is we

can assign the value right but what if

you have a integer value let's say int K

and now you are trying to assign or

maybe let's see let's get a byte value

byte K is equal to a e and let's comment

this section instead of saying B I want

to assign a value which is 257. now even

if you have a smaller value let's say 12

even this will not work because

ultimately the value the I mean the type

of a is integer right you can't assign a

integer to a byte format and if you run

this code you can say it will give you

error it will say incompatible types so

we got one way which is you can just

cast it with byte so we are doing a

typecasting here so when you run this

code now it will work you can say we got

12. now we got 12 because it is a in a

range of byte what happens when you have

a bigger value which is 257 now this is

out of range right so you come back here

run and you can see we got one as I

mentioned before it will perform a

modulus operation which is actually

finding the remainder so it will divide

this number by the byte range which is

256 it will find the remainder which is

one I hope this makes sense right so we

were able to do the byte conversion in

conversion this is working let's try

with flow code now so let's say we have

a float value which is f and the value

of float is 5.6 F at the end because

when you look at a float variable you

have to put at the at F at the end and

then we can create a integer value we

can say int let's say this time we'll go

for T it doesn't matter what variable

name you use and then if you try to put

f

and if we try to print the value of T

let's see what happens you can say we

got error again the same thing it is it

says there might be loss of the value

from this conversion but then I want to

do it I want to convert that so we can

put a casting again and we can say float

here and if we try to run this code so

you're trying to convert that into

integer right what's wrong with me and

let's try now and you can see we got

five so we lost that point six there now

this concept of casting is actually very

important when you start working on the

oops concept object in the further

concept this casting will be required

there as well at this point we are doing

casting on primitive values but later on

we'll also work with objects

okay now we have talked about casting so

what is conversion so conversion is

automatic casting or we can say

conversion is automatic conversion and

casting is explicit conversion so when

you specify something it is explicit

cool now there's one more concept which

is type promotion so what are what what

do you mean by type promotion so let's

say we have a byte value and the value

for byte let's say b or maybe let's say

a and the value is 10 here okay and then

we got a byte which is B is equal to 20.

and then when you perform the operation

maybe maybe this should be 129 let's

let's say this is study now when you

perform an operation on this let's say a

into B now whenever you do a into B

what 3 3 right so when you say 300 here

it is going out of byte now can you save

that into integer can I say int result

is equal to a into B now what is

happening here you're performing an

operation on buy So when you say byte

multiplied by it it should be byte right

but the problem is this value will go

out of range so Java says hey we will

promote you so this value will be

promoted into a integer value okay and

you can store that into integer so this

is called type promotions let's run this

and you can see we got an error because

we are printing T here let's print

result and run and you can see we got

300 so I hope it makes sense what is

Type conversion and casting and that's

it from this video