5- Generics and Primitive Types

Jun 20, 2026 05:32 · 2:24 · English · Whisper Turbo · 2 speakers

Цей трансферт застаріє в 24 Днів. Оновлення для постійного зберігання →

Lecture Index

0:03

S… Speaker 1 (5- Generics and Primitive Types)

When creating an instance of a generic type,

0:05

S… Speaker 1 (5- Generics and Primitive Types)

we can only use a reference type as a generic type argument.

0:09

S… Speaker 1 (5- Generics and Primitive Types)

Let me show you what I mean.

0:10

S… Speaker 1 (5- Generics and Primitive Types)

So I'm going to create a generic list of user.

0:14

S… Speaker 1 (5- Generics and Primitive Types)

We can pass the user class as a generic type argument because

0:18

S… Speaker 1 (5- Generics and Primitive Types)

this class is a reference type.

0:20

S… Speaker 1 (5- Generics and Primitive Types)

We can also use the object class or the string class.

0:23

S… Speaker 1 (5- Generics and Primitive Types)

These are all reference types in java.

0:26

S… Speaker 1 (5- Generics and Primitive Types)

but here we cannot pass the primitive integer type or short

0:30

S… Speaker 1 (5- Generics and Primitive Types)

or boolean or float,

0:31

S… Speaker 1 (5- Generics and Primitive Types)

these are all primitive types.

0:34

S… Speaker 1 (5- Generics and Primitive Types)

If you want to store these primitive values inside a generic list,

0:37

S… Speaker 1 (5- Generics and Primitive Types)

we have to use the wrapper class.

0:39

S… Speaker 1 (5- Generics and Primitive Types)

So every primitive type in Java has a wrapper class,

0:43

S… Speaker 1 (5- Generics and Primitive Types)

let me show you.

0:43

S… Speaker 2 (5- Generics and Primitive Types)

So,

0:44

S… Speaker 1 (5- Generics and Primitive Types)

for the primitive int,

0:46

S… Speaker 1 (5- Generics and Primitive Types)

we have the integer class,

0:49

S… Speaker 1 (5- Generics and Primitive Types)

for the float we have the float class,

0:51

S… Speaker 1 (5- Generics and Primitive Types)

for the boolean we have the boolean class and so on.

0:55

S… Speaker 1 (5- Generics and Primitive Types)

So this boolean class is a reference type that stores a boolean value.

1:00

S… Speaker 1 (5- Generics and Primitive Types)

So if you want to create a generic list of integers,

1:03

S… Speaker 1 (5- Generics and Primitive Types)

we have to write code like this.

1:04

S… Speaker 1 (5- Generics and Primitive Types)

New generic list of integer.

1:08

S… Speaker 1 (5- Generics and Primitive Types)

Now let's store this object in a variable of type generic

1:12

S… Speaker 1 (5- Generics and Primitive Types)

list of integer.

1:13

S… Speaker 1 (5- Generics and Primitive Types)

Call it numbers.

1:15

S… Speaker 2 (5- Generics and Primitive Types)

Now,

1:17

S… Speaker 1 (5- Generics and Primitive Types)

look over here.

1:18

S… Speaker 1 (5- Generics and Primitive Types)

This integer is grayed out because it's unnecessary.

1:22

S… Speaker 1 (5- Generics and Primitive Types)

We're duplicating our code.

1:23

S… Speaker 2 (5- Generics and Primitive Types)

So,

1:24

S… Speaker 1 (5- Generics and Primitive Types)

let's remove that.

1:26

S… Speaker 1 (5- Generics and Primitive Types)

That's better.

1:29

S… Speaker 1 (5- Generics and Primitive Types)

Now look at the signature of the add method.

1:32

S… Speaker 1 (5- Generics and Primitive Types)

It takes an instance of the integer class,

1:35

S… Speaker 1 (5- Generics and Primitive Types)

but we can pass a primitive integer like one and the Java compiler

1:39

S… Speaker 1 (5- Generics and Primitive Types)

will automatically wrap this value inside an instance of

1:43

S… Speaker 1 (5- Generics and Primitive Types)

the integer class.

1:44

S… Speaker 1 (5- Generics and Primitive Types)

So it's going to create an instance of the integer class to store this value.

1:48

S… Speaker 1 (5- Generics and Primitive Types)

This process is called boxing.

1:50

S… Speaker 1 (5- Generics and Primitive Types)

So the Java compiler is going to put this primitive value inside

1:55

S… Speaker 1 (5- Generics and Primitive Types)

a box.

1:55

S… Speaker 2 (5- Generics and Primitive Types)

Now,

1:56

S… Speaker 1 (5- Generics and Primitive Types)

when we call the get method,

1:59

S… Speaker 1 (5- Generics and Primitive Types)

look at the return type.

2:00

S… Speaker 1 (5- Generics and Primitive Types)

We get an instance of the integer class.

2:02

S… Speaker 2 (5- Generics and Primitive Types)

So,

2:03

S… Speaker 1 (5- Generics and Primitive Types)

let's get the first item and store it in a primitive int

2:07

S… Speaker 1 (5- Generics and Primitive Types)

called number.

2:08

S… Speaker 1 (5- Generics and Primitive Types)

Now in this case,

2:10

S… Speaker 1 (5- Generics and Primitive Types)

the Java compiler is going to extract the value that is stored in that integer

2:14

S… Speaker 1 (5- Generics and Primitive Types)

object.

2:14

S… Speaker 1 (5- Generics and Primitive Types)

This is called unboxing.

2:17

S… Speaker 1 (5- Generics and Primitive Types)

So this is how we can create generic types that work with primitive

2:21

S… Speaker 1 (5- Generics and Primitive Types)

values.

This transcript was generated by AI (automatic speech recognition). May contain errors — verify against the original audio for critical use. AI policy

❤️ Любите STT.ai? Розкажіть друзям!

Зведення

Натисніть Summarize, щоб створити резюме AI з цього запису.

Запитати комп' ютерного гравця про цей маршрутний індекс

Спитайте що-небудь про цей трансляція ⇩AI знайде відповідні частини і відповідь.

Транскрибувати ще