Meaning of lambda () -> in Java

up vote
15
down vote

favorite

I am looking at the following Stack Overflow answer:
How to change Spring's @Scheduled fixedDelay at runtime

And in the code there is the following line:

schedulerFuture = taskScheduler.schedule(() -> , this);

I would like to know what the lambda () -> means in that code. I need to write it without using lambdas.

edited 15 hours ago

Boann

35.6k1184116

asked yesterday

Aliuk

303517

25

It's a Runnable that does nothing.
â€“Â ernest_k
yesterday

first argument is runnable, so you are passing anonymous class of instance Runnable in which run method does nothing i.e. is empty.
â€“Â SMA
yesterday

3

without lambda, you would need to pass an anonymous Runnable with empty body, like new Runnable() @Override public void run()
â€“Â Alex Salauyou
yesterday

add a commentÂ |Â

up vote
15
down vote

favorite

I am looking at the following Stack Overflow answer:
How to change Spring's @Scheduled fixedDelay at runtime

And in the code there is the following line:

schedulerFuture = taskScheduler.schedule(() -> , this);

I would like to know what the lambda () -> means in that code. I need to write it without using lambdas.

edited 15 hours ago

Boann

35.6k1184116

asked yesterday

Aliuk

303517

25

It's a Runnable that does nothing.
â€“Â ernest_k
yesterday

first argument is runnable, so you are passing anonymous class of instance Runnable in which run method does nothing i.e. is empty.
â€“Â SMA
yesterday

3

without lambda, you would need to pass an anonymous Runnable with empty body, like new Runnable() @Override public void run()
â€“Â Alex Salauyou
yesterday

add a commentÂ |Â

up vote
15
down vote

favorite

I am looking at the following Stack Overflow answer:
How to change Spring's @Scheduled fixedDelay at runtime

And in the code there is the following line:

schedulerFuture = taskScheduler.schedule(() -> , this);

I would like to know what the lambda () -> means in that code. I need to write it without using lambdas.

edited 15 hours ago

Boann

35.6k1184116

asked yesterday

Aliuk

303517

I am looking at the following Stack Overflow answer:
How to change Spring's @Scheduled fixedDelay at runtime

And in the code there is the following line:

schedulerFuture = taskScheduler.schedule(() -> , this);

I would like to know what the lambda () -> means in that code. I need to write it without using lambdas.

java lambda java-8 java-7 java-9

edited 15 hours ago

Boann

35.6k1184116

asked yesterday

Aliuk

303517

edited 15 hours ago

Boann

35.6k1184116

asked yesterday

Aliuk

303517

edited 15 hours ago

Boann

35.6k1184116

edited 15 hours ago

Boann

35.6k1184116

edited 15 hours ago

Boann

35.6k1184116

asked yesterday

Aliuk

303517

asked yesterday

Aliuk

303517

asked yesterday

Aliuk

303517

25

It's a Runnable that does nothing.
â€“Â ernest_k
yesterday

first argument is runnable, so you are passing anonymous class of instance Runnable in which run method does nothing i.e. is empty.
â€“Â SMA
yesterday

3

without lambda, you would need to pass an anonymous Runnable with empty body, like new Runnable() @Override public void run()
â€“Â Alex Salauyou
yesterday

add a commentÂ |Â

25

It's a Runnable that does nothing.
â€“Â ernest_k
yesterday

first argument is runnable, so you are passing anonymous class of instance Runnable in which run method does nothing i.e. is empty.
â€“Â SMA
yesterday

3

without lambda, you would need to pass an anonymous Runnable with empty body, like new Runnable() @Override public void run()
â€“Â Alex Salauyou
yesterday

It's a Runnable that does nothing.
â€“Â ernest_k
yesterday

first argument is runnable, so you are passing anonymous class of instance Runnable in which run method does nothing i.e. is empty.
â€“Â SMA
yesterday

without lambda, you would need to pass an anonymous Runnable with empty body, like new Runnable() @Override public void run()
â€“Â Alex Salauyou
yesterday

add a commentÂ |Â

4 Answers
4

active

oldest

votes

up vote
35
down vote

accepted

Its a Runnable with an empty run definition. The anonymous class representation of this would be:

new Runnable() 
 @Override public void run() 
 // could have done something here

edited 18 hours ago

dun

295

answered yesterday

nullpointer

30.4k1054127

2

Related: stackoverflow.com/a/26553481/1076640 (contains commentary on why the idiom is () -> and not Runnable.noop, from one of the Java designers).
â€“Â yshavit
15 hours ago

add a commentÂ |Â

up vote
2
down vote

Lamda expression is an anonymous function that allows you to pass methods as arguments or simply, a mechanism that helps you remove a lot of boilerplate code. They have no access modifier(private, public or protected), no return type declaration and no name.

Lets take a look at this example.

(int a, int b) -> return a > b

In your case, you can do something like below:

schedulerFuture = taskScheduler.schedule(new Runnable() 
 @Override 
 public void run() 
 // task details
 
, this);

edited yesterday

answered yesterday

Prashant Goswami

1035

add a commentÂ |Â

up vote
1
down vote

For lambdas:

Left side is arguments, what you take. Enclosed in () are all the arguments this function takes

-> indicates that it's a function that takes what's on the left and passes it on to the right for processing

Right side is the body - what the lambda does. Enclosed in is everything this function does

After you figure that out you only need to know that that construction passes an instance of matching class (look at what's the expected argument type in the schedule() call) with it's only method doing exactly the same as the lambda expression we've just analyzed.

answered yesterday

Deltharis

1,64911125

add a commentÂ |Â

up vote
-1
down vote

Lambda expressions basically express instances of functional interfaces.
In a way Lambda expression will be: (lambda operator params) -> body

() -> System.out.println("This means Lambda expression is not taking any parameters");

(p) -> System.out.println("Lambda expression with one parameter: " + p);

answered yesterday

Archit Sud

725

This doesn't answer the question - why the empty lambda. This is just a general explainer of what lambdas are.
â€“Â Andrejs
18 hours ago

@Andrejs, why you have down, voted my answer. Did you see what user has asked here? Let me repeat it for you. Here is the last line of the question "I would like to know what the lambda () -> means in that code. I need to write it without using lambdas." He as asked for the meaning of () ->
â€“Â Archit Sud
6 hours ago

add a commentÂ |Â

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4 Answers
4

active

oldest

votes

4 Answers
4

active

oldest

votes

up vote
35
down vote

accepted

Its a Runnable with an empty run definition. The anonymous class representation of this would be:

new Runnable() 
 @Override public void run() 
 // could have done something here

edited 18 hours ago

dun

295

answered yesterday

nullpointer

30.4k1054127

2

Related: stackoverflow.com/a/26553481/1076640 (contains commentary on why the idiom is () -> and not Runnable.noop, from one of the Java designers).
â€“Â yshavit
15 hours ago

add a commentÂ |Â

up vote
35
down vote

accepted

Its a Runnable with an empty run definition. The anonymous class representation of this would be:

new Runnable() 
 @Override public void run() 
 // could have done something here

edited 18 hours ago

dun

295

answered yesterday

nullpointer

30.4k1054127

2

Related: stackoverflow.com/a/26553481/1076640 (contains commentary on why the idiom is () -> and not Runnable.noop, from one of the Java designers).
â€“Â yshavit
15 hours ago

add a commentÂ |Â

up vote
35
down vote

accepted

Its a Runnable with an empty run definition. The anonymous class representation of this would be:

new Runnable() 
 @Override public void run() 
 // could have done something here

edited 18 hours ago

dun

295

answered yesterday

nullpointer

30.4k1054127

Its a Runnable with an empty run definition. The anonymous class representation of this would be:

new Runnable() 
 @Override public void run() 
 // could have done something here

edited 18 hours ago

dun

295

answered yesterday

nullpointer

30.4k1054127

edited 18 hours ago

dun

295

edited 18 hours ago

dun

295

edited 18 hours ago

dun

295

answered yesterday

nullpointer

30.4k1054127

answered yesterday

nullpointer

30.4k1054127

answered yesterday

nullpointer

30.4k1054127

2

Related: stackoverflow.com/a/26553481/1076640 (contains commentary on why the idiom is () -> and not Runnable.noop, from one of the Java designers).
â€“Â yshavit
15 hours ago

add a commentÂ |Â

2

Related: stackoverflow.com/a/26553481/1076640 (contains commentary on why the idiom is () -> and not Runnable.noop, from one of the Java designers).
â€“Â yshavit
15 hours ago

Related: stackoverflow.com/a/26553481/1076640 (contains commentary on why the idiom is () -> and not Runnable.noop, from one of the Java designers).
â€“Â yshavit
15 hours ago

add a commentÂ |Â

up vote
2
down vote

Lets take a look at this example.

(int a, int b) -> return a > b

In your case, you can do something like below:

schedulerFuture = taskScheduler.schedule(new Runnable() 
 @Override 
 public void run() 
 // task details
 
, this);

edited yesterday

answered yesterday

Prashant Goswami

1035

add a commentÂ |Â

up vote
2
down vote

Lets take a look at this example.

(int a, int b) -> return a > b

In your case, you can do something like below:

schedulerFuture = taskScheduler.schedule(new Runnable() 
 @Override 
 public void run() 
 // task details
 
, this);

edited yesterday

answered yesterday

Prashant Goswami

1035

add a commentÂ |Â

up vote
2
down vote

Lets take a look at this example.

(int a, int b) -> return a > b

In your case, you can do something like below:

schedulerFuture = taskScheduler.schedule(new Runnable() 
 @Override 
 public void run() 
 // task details
 
, this);

edited yesterday

answered yesterday

Prashant Goswami

1035

Lets take a look at this example.

(int a, int b) -> return a > b

In your case, you can do something like below:

schedulerFuture = taskScheduler.schedule(new Runnable() 
 @Override 
 public void run() 
 // task details
 
, this);

edited yesterday

answered yesterday

Prashant Goswami

1035

edited yesterday

answered yesterday

Prashant Goswami

1035

answered yesterday

Prashant Goswami

1035

answered yesterday

Prashant Goswami

1035

add a commentÂ |Â

up vote
1
down vote

For lambdas:

Left side is arguments, what you take. Enclosed in () are all the arguments this function takes

-> indicates that it's a function that takes what's on the left and passes it on to the right for processing

Right side is the body - what the lambda does. Enclosed in is everything this function does

answered yesterday

Deltharis

1,64911125

add a commentÂ |Â

up vote
1
down vote

For lambdas:

Left side is arguments, what you take. Enclosed in () are all the arguments this function takes

-> indicates that it's a function that takes what's on the left and passes it on to the right for processing

Right side is the body - what the lambda does. Enclosed in is everything this function does

answered yesterday

Deltharis

1,64911125

add a commentÂ |Â

up vote
1
down vote

For lambdas:

Left side is arguments, what you take. Enclosed in () are all the arguments this function takes

-> indicates that it's a function that takes what's on the left and passes it on to the right for processing

Right side is the body - what the lambda does. Enclosed in is everything this function does

answered yesterday

Deltharis

1,64911125

For lambdas:

Left side is arguments, what you take. Enclosed in () are all the arguments this function takes

-> indicates that it's a function that takes what's on the left and passes it on to the right for processing

Right side is the body - what the lambda does. Enclosed in is everything this function does

answered yesterday

Deltharis

1,64911125

answered yesterday

Deltharis

1,64911125

answered yesterday

Deltharis

1,64911125

answered yesterday

Deltharis

1,64911125

add a commentÂ |Â

up vote
-1
down vote

Lambda expressions basically express instances of functional interfaces.
In a way Lambda expression will be: (lambda operator params) -> body

() -> System.out.println("This means Lambda expression is not taking any parameters");

(p) -> System.out.println("Lambda expression with one parameter: " + p);

answered yesterday

Archit Sud

725

This doesn't answer the question - why the empty lambda. This is just a general explainer of what lambdas are.
â€“Â Andrejs
18 hours ago

@Andrejs, why you have down, voted my answer. Did you see what user has asked here? Let me repeat it for you. Here is the last line of the question "I would like to know what the lambda () -> means in that code. I need to write it without using lambdas." He as asked for the meaning of () ->
â€“Â Archit Sud
6 hours ago

add a commentÂ |Â

up vote
-1
down vote

Lambda expressions basically express instances of functional interfaces.
In a way Lambda expression will be: (lambda operator params) -> body

() -> System.out.println("This means Lambda expression is not taking any parameters");

(p) -> System.out.println("Lambda expression with one parameter: " + p);

answered yesterday

Archit Sud

725

This doesn't answer the question - why the empty lambda. This is just a general explainer of what lambdas are.
â€“Â Andrejs
18 hours ago

@Andrejs, why you have down, voted my answer. Did you see what user has asked here? Let me repeat it for you. Here is the last line of the question "I would like to know what the lambda () -> means in that code. I need to write it without using lambdas." He as asked for the meaning of () ->
â€“Â Archit Sud
6 hours ago

add a commentÂ |Â

up vote
-1
down vote

Lambda expressions basically express instances of functional interfaces.
In a way Lambda expression will be: (lambda operator params) -> body

() -> System.out.println("This means Lambda expression is not taking any parameters");

(p) -> System.out.println("Lambda expression with one parameter: " + p);

answered yesterday

Archit Sud

725

Lambda expressions basically express instances of functional interfaces.
In a way Lambda expression will be: (lambda operator params) -> body

() -> System.out.println("This means Lambda expression is not taking any parameters");

(p) -> System.out.println("Lambda expression with one parameter: " + p);

answered yesterday

Archit Sud

725

answered yesterday

Archit Sud

725

answered yesterday

Archit Sud

725

answered yesterday

Archit Sud

725

This doesn't answer the question - why the empty lambda. This is just a general explainer of what lambdas are.
â€“Â Andrejs
18 hours ago

@Andrejs, why you have down, voted my answer. Did you see what user has asked here? Let me repeat it for you. Here is the last line of the question "I would like to know what the lambda () -> means in that code. I need to write it without using lambdas." He as asked for the meaning of () ->
â€“Â Archit Sud
6 hours ago

add a commentÂ |Â

This doesn't answer the question - why the empty lambda. This is just a general explainer of what lambdas are.
â€“Â Andrejs
18 hours ago

@Andrejs, why you have down, voted my answer. Did you see what user has asked here? Let me repeat it for you. Here is the last line of the question "I would like to know what the lambda () -> means in that code. I need to write it without using lambdas." He as asked for the meaning of () ->
â€“Â Archit Sud
6 hours ago

This doesn't answer the question - why the empty lambda. This is just a general explainer of what lambdas are.
â€“Â Andrejs
18 hours ago

@Andrejs, why you have down, voted my answer. Did you see what user has asked here? Let me repeat it for you. Here is the last line of the question "I would like to know what the lambda () -> means in that code. I need to write it without using lambdas." He as asked for the meaning of () ->
â€“Â Archit Sud
6 hours ago

add a commentÂ |Â

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