Java：迭代2个列表的最佳/优雅方式

Question

Assume I have a List<SomeObject> a .
Now also assume that I have another List<SomeProcessor> b .
Each SomeProcessor uses a for its processing.

Besides:

int idx = 0;   
for(SomeProcessor o:b){  
    o2 = a.get(idx);  
    o.doSomething(o2);  
    idx++;   
}

Is there a more elegant way to handle this?

Answer 1

public interface Processor<T> {
    public void process(T object);
}

And then a helper method:

public static <T> void processAll(Collection<T> items, Collection<? extends Processor<T>> processors) {
    Iterator<T> i = items.iterator();
    Iterator<? extends Processor<T>> p = processors.iterator();
    while(i.hasNext() && p.hasNext())
        p.next().process(i.next()); 
}

You could put that helper method on the class which uses it, if there is only one (and make it private ), or put it a utility class which is shared by the entire program.

Of course there are other ways to code processAll ; for example, you could use a for loop on one of the collections. But in any case, breaking this low-level code out into a helper method will make your higher-level code cleaner and less "noisy". And if you are doing something similar in multiple parts of the program, they can share the helper method.

Answer 2

If you can generate a Map<SomeObject, SomeProcessor> instead of two lists, then it'll be elegant. This may not apply, but I'll just give it a shot.

Answer 3

Maybe you can try with this simpler way :

int idx = 0;
while(idx<a.size() && idx<b.size()){   
    b.get(idx).doSomething(a.get(idx++));
}