Stream confusion

[Archie Cobbs]

I have an API design question about Streams, but instead of asking the
question outright I thought I'd ask it indirectly with a simple example.

The Javadoc for Stream opens with this example:

        int sum = widgets.stream()
                      .filter(w -> w.getColor() == RED)
                      .mapToInt(w -> w.getWeight())
                      .sum();

OK, looks reasonable - we're computing the sum of the weights of all the
red widgets.

Here's the question: Is the following program deterministic?

import java.awt.*;
import java.util.function.*;
import java.util.stream.*;
import static java.awt.Color.*;

public class Widget {

    private final Color color;
    private final int weight;

    public Widget(Color color, int weight) {
        this.color = color;
        this.weight = weight;
    }

    public Color getColor() {
        return this.color;
    }

    public int getWeight() {
        return this.weight;
    }

    public static int totalRedWeight(Widget... widgets) {
        return Stream.of(widgets)
                .filter(w -> w.getColor() == RED)
                .mapToInt(w -> w.getWeight())
                .sum();
    }

// Test method

    public static void main(String[] args) {
        final Widget w1 = new Widget(RED, 123);
        final Widget w2 = new Widget(BLUE, 456);
        final int total = Widget.totalRedWeight(w1, w2);
        System.out.println("Total red weight = " + total);
    }
}

-Archie

-- 
Archie L. Cobbs
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