2017.01.28 Material for Toyama Buri Kaigi

25. From External Iteration
To Internal Iteration
List<Long> nums = ...;
List<Long> nums2
= new ArrayList<>();
for (long n: nums) {
nums2.add(n*2L);
}
Before

26. From External Iteration
To Internal Iteration
List<Long> nums = ...;
List<Long> nums2 = nums.stream()
.map(new Function<Long,Long>(){
@Override
public Long aply(Long n) {
return n*2L;
}
})
.collect(Collectors.toList());

27. From External Iteration
To Internal Iteration
List<Long> nums = ...;
List<Long> nums2 = nums.stream()
.map(new Function<Long,Long>(){
@Override
public Long aply(Long n) {
return n*2L;
}
})
.collect(Collectors.toList());
Boilerplate!

28. From External Iteration
To Internal Iteration
List<Long> nums = ...;
List<Long> nums2 = nums.stream()
.map(
n -> n*2L
)
.collect(Collectors.toList());
After