检查ArrayList是否只包含null值的方法。

I was looking through the code for an old Android application of mine, and I saw one thing I did to the effect of this:

我正在查看我的一个旧的Android应用程序的代码，我发现我做了一件事:

        boolean emptyArray = true;
        for (int i = 0; i < array.size(); i++)
        {
            if (array.get(i) != null)
            {
                    emptyArray = false;
                    break;
            }
        }
        if (emptyArray == true)
        {
            return true;
        }
        return false;

There has to be a more efficient way of doing this -- but what is it?

必须有一种更有效的方法来做到这一点——但它是什么呢?

emptyArray is defined as an ArrayList of Integers, which are inserted with a random number of null values (And later in the code, actual integer values).

emptyArray定义为一个整数的ArrayList，它插入了随机数的空值(在后面的代码中是实际的整数值)。

Thanks!

谢谢!

4 个解决方案

#1

There is no more efficient way. The only thing is you can do, is write it in more elegant way:

没有更有效的方法。你唯一能做的就是，用更优雅的方式写出来:

List<Something> l;

boolean nonNullElemExist= false;
for (Something s: l) {
  if (s != null) {
     nonNullElemExist = true;
     break;
  }
}

// use of nonNullElemExist;

Actually, it is possible that this is more efficient, since it uses Iterator and the Hotspot compiler has more info to optimize instead using size() and get().

实际上，这可能更有效，因为它使用迭代器，Hotspot编译器有更多的信息来优化，而不是使用size()和get()。

4 个解决方案

#1

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