6- Method References

Jun 27, 2026 00:00 · 3:46 · English · Whisper Turbo · 2 Speakers

This transcript expires today. Upgrade for permanent storage →

Lecture Index

0:03

S… Speaker 1 (6- Method References)

Sometimes all we do in a lambda expression is passing the parameter or

0:07

S… Speaker 1 (6- Method References)

parameters to an existing method.

0:09

S… Speaker 1 (6- Method References)

For example,

0:10

S… Speaker 1 (6- Method References)

over here, we're simply passing this message to the print line method of

0:14

S… Speaker 1 (6- Method References)

this object.

0:15

S… Speaker 1 (6- Method References)

In these cases,

0:16

S… Speaker 1 (6- Method References)

it's easier to reference this method directly.

0:19

S… Speaker 1 (6- Method References)

Let me show you.

0:19

S… Speaker 1 (6- Method References)

So,

0:20

S… Speaker 1 (6- Method References)

here's the syntax.

0:22

S… Speaker 1 (6- Method References)

We type the name of the class or the object that contains this method.

0:27

S… Speaker 1 (6- Method References)

Then we type double colons followed by the name of the method without

0:31

S… Speaker 1 (6- Method References)

parentheses because we don't want to call this method We just want to add a reference

0:35

S… Speaker 1 (6- Method References)

to it.

0:35

S… Speaker 1 (6- Method References)

For example,

0:36

S… Speaker 1 (6- Method References)

if I want to rewrite this lambda expression using a method reference,

0:40

S… Speaker 1 (6- Method References)

I would type greet Now what is the object

0:45

S… Speaker 1 (6- Method References)

that contains the print line method?

0:46

S… Speaker 1 (6- Method References)

It's this object,

0:48

S… Speaker 1 (6- Method References)

right? So we type system that out then we add double colons

0:52

S… Speaker 1 (6- Method References)

followed by the name of the method without parentheses so

0:58

S… Speaker 1 (6- Method References)

this is a method reference,

0:59

S… Speaker 1 (6- Method References)

and this code is identical to what we have over here.

1:02

S… Speaker 2 (6- Method References)

Now,

1:03

S… Speaker 1 (6- Method References)

with IntelliJ,

1:04

S… Speaker 1 (6- Method References)

we can always convert this kind of lambda expressions to a method reference very

1:08

S… Speaker 1 (6- Method References)

easily.

1:08

S… Speaker 1 (6- Method References)

So we put the character on the body of the lambda,

1:11

S… Speaker 1 (6- Method References)

press alt and enter,

1:12

S… Speaker 1 (6- Method References)

and then replace lambda with method reference.

1:15

S… Speaker 1 (6- Method References)

There you go.

1:16

S… Speaker 2 (6- Method References)

Now,

1:17

S… Speaker 1 (6- Method References)

with this method references,

1:19

S… Speaker 1 (6- Method References)

we can reference static or instance methods in a class,

1:22

S… Speaker 1 (6- Method References)

as well as constructors.

1:23

S… Speaker 1 (6- Method References)

Let me show you a few examples.

1:25

S… Speaker 1 (6- Method References)

So I'm going to delete these.

1:28

S… Speaker 1 (6- Method References)

and add a static method in this class,

1:30

S… Speaker 1 (6- Method References)

public static void print message.

1:34

S… Speaker 1 (6- Method References)

Now the signature of this method matches the print

1:39

S… Speaker 1 (6- Method References)

method of our printer interface,

1:40

S… Speaker 1 (6- Method References)

okay?

1:41

S… Speaker 1 (6- Method References)

So here we call the greet method,

1:44

S… Speaker 1 (6- Method References)

we should pass a printer object,

1:47

S… Speaker 1 (6- Method References)

so here we can use a lambda expression,

1:49

S… Speaker 1 (6- Method References)

message,

1:50

S… Speaker 1 (6- Method References)

we take it and pass it to this method.

1:54

S… Speaker 1 (6- Method References)

Right again,

1:55

S… Speaker 1 (6- Method References)

all we're doing here is passing the parameter to an existing method so we can

1:59

S… Speaker 1 (6- Method References)

use a method reference here We type the name of the class that contains this method

2:03

S… Speaker 1 (6- Method References)

in this case lambdas demo so Lambdas

2:08

S… Speaker 1 (6- Method References)

demo then double colons followed by the name of the method There

2:13

S… Speaker 1 (6- Method References)

you go or you can convert this using IntelliJ now

2:17

S… Speaker 1 (6- Method References)

what if this was an instance method?

2:19

S… Speaker 1 (6- Method References)

Let's see how it works.

2:22

S… Speaker 1 (6- Method References)

So I'm going to create

2:25

S… Speaker 1 (6- Method References)

a lambdasDemo object,

2:27

S… Speaker 1 (6- Method References)

demo,

2:28

S… Speaker 1 (6- Method References)

we set it to a new instance of the lambdasDemo class.

2:31

S… Speaker 1 (6- Method References)

Now we want to call the greet method and pass a lambda expression

2:35

S… Speaker 1 (6- Method References)

like this.

2:36

S… Speaker 1 (6- Method References)

Message goes to demo dot,

2:39

S… Speaker 1 (6- Method References)

here we want to call this instance method,

2:41

S… Speaker 1 (6- Method References)

so print message.

2:43

S… Speaker 2 (6- Method References)

Now,

2:44

S… Speaker 1 (6- Method References)

to use a method reference,

2:46

S… Speaker 1 (6- Method References)

we type the name of the object that contains this method,

2:49

S… Speaker 1 (6- Method References)

demo,

2:50

S… Speaker 1 (6- Method References)

double colons,

2:51

S… Speaker 1 (6- Method References)

and print.

2:54

S… Speaker 1 (6- Method References)

If we use IntelliJ,

2:55

S… Speaker 1 (6- Method References)

we get the exact same result.

2:58

S… Speaker 2 (6- Method References)

Now,

2:59

S… Speaker 1 (6- Method References)

what about passing a value to a constructor?

3:01

S… Speaker 1 (6- Method References)

Let's take a look.

3:02

S… Speaker 1 (6- Method References)

So delete.

3:03

S… Speaker 1 (6- Method References)

I'm going to add a constructor here.

3:05

S… Speaker 1 (6- Method References)

In this constructor,

3:08

S… Speaker 1 (6- Method References)

we want to add a string parameter.

3:10

S… Speaker 2 (6- Method References)

Now,

3:11

S… Speaker 1 (6- Method References)

let's say we call the greet method and pass

3:16

S… Speaker 1 (6- Method References)

a message to the constructor of the LambdasDemo class.

3:20

S… Speaker 1 (6- Method References)

How can we use a method reference

3:24

S… Speaker 1 (6- Method References)

here? Well,

3:25

S… Speaker 1 (6- Method References)

we type the name of the class

3:28

S… Speaker 1 (6- Method References)

that is lambdas demo,

3:29

S… Speaker 1 (6- Method References)

double colon,

3:30

S… Speaker 1 (6- Method References)

and here we type new to represent the constructor.

3:34

S… Speaker 1 (6- Method References)

If we use IntelliJ,

3:36

S… Speaker 1 (6- Method References)

we get the exact same result.

3:38

S… Speaker 1 (6- Method References)

So with method references,

3:40

S… Speaker 1 (6- Method References)

we can write compact and easier to read lambda expressions.

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

❤️ Love STT.ai? Tell your friends!

Summary

Click Summarize to generate an AI summary of this transcript.

Ask AI About This Transcript

Ask anything about this transcript — the AI will find relevant sections and answer.

Transcribe Another