将Java 8流降级到Intellij IDEA中的Java 7循环

Question

I have some code written using Java 8 features, which means streams and lambdas. Now, I have to reuse such code in a project that uses Java 7. Is there the possibility to automatically refactor the code using IntelliJ?

For example, I have to refactor some code that looks like the following, into a simple for / while loop.

Arrays.stream(values)
      .distinct()
      .limit(2)
      .count();

Answer 1

Yes, IntelliJ has "Replace Stream API chain with loop" refactor option. It pops up after pressing Alt+Enter after placing cursor on the Arrays.stream() method:

It will produce code like:

long count = 0L;
long limit = 2;
Set<Integer> uniqueValues = new HashSet<>();
for (int i : new int[]{1, 2, 3}) {
    if (uniqueValues.add(i)) {
        if (limit-- == 0) break;
        count++;
    }
}
System.out.println(count);

For the option to work the project language level has to be 8 or higher.

Answer 2

You really don't need that much of code for the current logic though(refactoring here seems not optimal and less readable to me atleast.)

What also works is simply using a Set and working around its size:

Set<String> set = new HashSet<>(values);
System.out.println(set.size() > 2 ? 2 : set.size());