All Questions
5,405
questions
-2
votes
2
answers
69
views
Clarity on Java Lambda Syntax [duplicate]
From my understanding, this is a single statement in Java:
while((x % p == 0l) && (x > p)) x /= p;
If that is the case, why is this a syntax error:
final AtomicLong subtotal = new ...
- 5,416
0
votes
0
answers
70
views
How does the lambda work? How does it know to call the functional interface? I want details because nothing I've seen explains it well [duplicate]
This is in a javafx program and it runs.
button.setOnAction(_ ->{
int side = 0;
Random rand = new Random();
side = rand.nextInt(2);
if(side == 0){
//code here
else{
...
12
votes
1
answer
590
views
Ambiguity in method references
Consider the following snippet:
public static void main(String[] args) {
Function<String, String> function = String::toUpperCase; //OK
// Comparator<String> ...
- 123
0
votes
2
answers
195
views
Predicates and functions
public static void main(String[] args) {
List<String> strings = Arrays.asList("a", "b", "c", "d");
strings.stream()
.filter(s -> ...
- 3,915
1
vote
0
answers
22
views
Why Optional lambda replace with method reference Causing NullPointerException [duplicate]
There is a A Class
class A {
private String str;
public void setStr(String str) {
this.str = str;
}
}
this method works fine;
public static void main(String[] args) {
...
- 11
1
vote
1
answer
54
views
How to break an iteration and modify parent with child value in a nested list using java streams
I have this scenario:
public class A {
private String aValue;
private List<B> bList;
}
public class B {
private List<C> cList;
}
public class C {
private String cValue;
}
...
- 11
-1
votes
2
answers
108
views
How to remove these braces around this lamda expression?
Sonarlint I use with IntelliJ sends me a warning S1602 "Remove useless curly braces around statement" on this statement :
communes.foreachPartition(
partition -> {
partition....
- 3,121
-3
votes
1
answer
59
views
Can I use a lambda expression to return a single value of a collections? [duplicate]
I have a Collection of and I want to make a simple filter to obtain a T value, for example an
getById( int idOfT)
I tried this:
return (T) stream.filter( t -> t.getId().equals(id));
but it does'...
- 56
1
vote
3
answers
103
views
Is this a correct interpretation of what computeIfAbsent is doing in this code?
I am reading someone else's code which uses computeIfAbsent. I don't often use lambdas, and I want to be cautious as I try to understand what it's doing. Rewriting this for my own understanding, is ...
- 2,635
0
votes
0
answers
43
views
Creation multimap throught lambda-expression
I am reading a book "Effective Java" and coming up with fragmnet of code:
public enum Phase {
SOLID, LIQUID, GAS;
public enum Transition {
MELT(SOLID, LIQUID), FREEZE(...
2
votes
2
answers
82
views
Compare two different java collection objects with a common attribute using java streams api
I have two Sets containing 2 different objects
1. Set<A>
2. Set<B>
class A {
private String id;
private String name;
private B objB;
}
class B {
...
- 375
1
vote
1
answer
43
views
Unexpect Behavior with Multiple Java Threads and TreeMap.put()
When running the following code:
import java.util.Collections;
import java.util.Map;
import java.util.TreeMap;
public final class ThreadTest {
int N = 4;
Map<Integer, Proxy> proxy = ...
- 11
0
votes
1
answer
37
views
Junit for Consumer class returning lambda
I am writing junit test case for below for consumer class which has below method.
@Bean
@Transactional
public Consumer<Message<String>> response() {
return message -> {
...
- 1
-1
votes
2
answers
76
views
lambda function uses member variable and produces different results
I dont know why the code runs without errors. From what I learned, in functional programming, same input results in same output and function's internal state cannot be changed from outside. When I ...
- 11
0
votes
0
answers
34
views
Java lambdas/method references used as callbacks in addCallback/removeCallback style methods
I've read about this but I haven't found a clear answer.
Assume an API like the following:
Callback callback = new Callback();
myApi.addCallback(callback);
[...]
myApi.removeCallback(callback);
Now, ...
- 105