iterate through only even/odd items with Java lambda-CodePudding

I have a list that contains computed values and I can not change or transform the list to e.g. Map. I need to iterate through this list and get all the odd/even items. To do this with the old fashion Java for loop is quite easy.

Let's say that I have this list:

var results = Arrays.asList("1", "2", "3", "4", "5", "6");

Get all odd items:

for (int i = 0; i < results.size(); i  = 2) {
    var current = results.get(i);
    process(current);
}

Get all even items:

for (int i = 1; i < results.size(); i  = 2) {
    var current = results.get(i);
    process(current);
}

Can I get somehow the same result with lambda forEach() easily in one line?

>UPDATE<

Sorry for this, but I forgot to mention that the values actually are not numbers like 1, 2, 3, etc. I just used these values as an example. The solution must not rely on the value of the items.

CodePudding user response：

An alternative could be to use Stream.iterate

IntStream.iterate(0, i -> i < results.size(), i -> i 2)
         .mapToObj(i -> results.get(i))
         .forEach(this::process);

IntStream.iterate(1, i -> i < results.size(), i -> i 2)
         .mapToObj(i -> results.get(i))
         .forEach(this::process);

Use YourClass::process if process a static method.

CodePudding user response：

Based on your update to the question

You could do something like this:

// even elements
IntStream.range(0, results.size())
                .filter(i -> i % 2 == 0)
                .mapToObj(results::get)
                .forEach(this::process);

// odd elements
IntStream.range(0, results.size())
                .filter(i -> i % 2 != 0)
                .mapToObj(results::get)
                .forEach(this::process);