0

Actionscript 使用稀疏数组,所以我可以有一个这样的数组:

var myArray:Array = new Array();
myArray[0] = "foo";
myArray[22] = "bar";

现在 myArray.length 将给我 23。有没有办法在不迭代每个元素的情况下获取数组中的实际项目数?

4

3 回答 3

1

通过使用for语法,它将迭代定义的索引:

public static function definedCount(arr:Array):uint {
    var ctr:uint = 0;
    for(ix:* in arr)
        ctr++;
    return ctr;
}

如果您需要经常检查稀疏数组中的项目数,则应将其包装为一个单独跟踪项目数的集合类。就像是:

public class IndexedCollection { 
    private var _arr:Array = [];
    private var _itemCount:uint = 0;

    public function get count():uint {
        return _itemCount;
    }

    public function getItem(index:uint):* { 
        return _arr[index]; 
    }

    public function setItem(index:uint, value:*):void {
        if(_arr[index] === undefined)
            _itemCount++;
        _arr[index] = value; 
    }

    public function delete(index:uint):void { 
        if(_arr[index] === undefined) 
            return;
        delete _arr[index]; 
        _itemCount--;
    }
}
于 2012-09-06T21:11:12.673 回答
1

如果您不想遍历数组,可以对其进行过滤:

var myArray:Array = new Array();
myArray[0] = "foo";
myArray[22] = "bar";

var numberOfItems:int = myArray.toString().split(',').filter(isItem).length;

function isItem(item:*, index:int, array:Array):Boolean
{
  return item != "";
}
于 2012-09-06T21:22:58.807 回答
1

最快的方法应该是始终使用内置函数。

    function myFilter(item:*, index:int, array:Array):Boolean{
        if(item)
        {
            return true;
        }else{
            return false;
        }
    }

    var myArray:Array = new Array();
    myArray[0] = "foo";
    myArray[22] = "bar";
    trace(myArray.length) // 23
    var myMyNewArray:Array = myArray.filter(myFilter)
    trace(myMyNewArray .length) // 2
于 2012-09-07T13:59:54.873 回答