#8 Type Conversion in Java
Summary
TLDRThis 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
🔢 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.
📊 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.
🌐 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.
Mindmap
Keywords
💡Type
💡Variable
💡Type Conversion
💡Type Casting
💡Range
💡Modulus Operator
💡Implicit Conversion
💡Data Loss
💡Type Promotion
💡Primitive Values
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
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