ADDITIONAL SYSTEM INFORMATION :
Any OS

A DESCRIPTION OF THE PROBLEM :
When I try create a new list with ::new function:

public class NewFunctionTest {

public static void main(String[] args) {
int count = 100000;
List<A> list = new ArrayList();
for(int i = 0 ; i < count ; i++) {
int key = ThreadLocalRandom.current().nextInt(100000);
int value = ThreadLocalRandom.current().nextInt(1000000);
list.add(new A(key, value));
}
System.out.println("init list done");
Map<Integer, List<Integer>> map = new HashMap();
for(A a : list) {
map.computeIfAbsent(a.getKey(), ArrayList::new);
}
System.out.println("finish function");
}

@Getter
@AllArgsConstructor
public static class A {

private int key;
private int value;

}
}

I got error:

init list done
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.util.ArrayList.<init>(ArrayList.java:153)
at com.tvd12.example.function.NewFunctionTest$$Lambda$1/1705736037.apply(Unknown Source)
at java.util.HashMap.computeIfAbsent(HashMap.java:1127)
at com.tvd12.example.function.NewFunctionTest.main(NewFunctionTest.java:25)

But when i modify to k -> new ArrayList():

public class NewFunctionTest {

public static void main(String[] args) {
int count = 100000;
List<A> list = new ArrayList();
for(int i = 0 ; i < count ; i++) {
int key = ThreadLocalRandom.current().nextInt(100000);
int value = ThreadLocalRandom.current().nextInt(1000000);
list.add(new A(key, value));
}
System.out.println("init list done");
Map<Integer, List<Integer>> map = new HashMap();
for(A a : list) {
map.computeIfAbsent(a.getKey(), k -> new ArrayList());
}
System.out.println("finish function");
}

@Getter
@AllArgsConstructor
public static class A {

private int key;
private int value;

}

}

It's ok



ACTUAL -
init list done
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.util.ArrayList.<init>(ArrayList.java:153)
at com.tvd12.example.function.NewFunctionTest$$Lambda$1/1705736037.apply(Unknown Source)
at java.util.HashMap.computeIfAbsent(HashMap.java:1127)
at com.tvd12.example.function.NewFunctionTest.main(NewFunctionTest.java:25)

---------- BEGIN SOURCE ----------
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ThreadLocalRandom;

import lombok.AllArgsConstructor;
import lombok.Getter;

public class NewFunctionTest {

public static void main(String[] args) {
int count = 100000;
List<A> list = new ArrayList<>();
for(int i = 0 ; i < count ; i++) {
int key = ThreadLocalRandom.current().nextInt(100000);
int value = ThreadLocalRandom.current().nextInt(1000000);
list.add(new A(key, value));
}
System.out.println("init list done");
Map<Integer, List<Integer>> map = new HashMap<>();
for(A a : list) {
map.computeIfAbsent(a.getKey(), ArrayList::new);
}
System.out.println("finish function");
}

@Getter
@AllArgsConstructor
public static class A {

private int key;
private int value;

}

}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ThreadLocalRandom;

import lombok.AllArgsConstructor;
import lombok.Getter;

public class NewFunctionTest {

public static void main(String[] args) {
int count = 100000;
List<A> list = new ArrayList<>();
for(int i = 0 ; i < count ; i++) {
int key = ThreadLocalRandom.current().nextInt(100000);
int value = ThreadLocalRandom.current().nextInt(1000000);
list.add(new A(key, value));
}
System.out.println("init list done");
Map<Integer, List<Integer>> map = new HashMap<>();
for(A a : list) {
map.computeIfAbsent(a.getKey(), k -> new ArrayList<>());
}
System.out.println("finish function");
}

@Getter
@AllArgsConstructor
public static class A {

private int key;
private int value;

}

}

FREQUENCY : always