Question

以下使用排序比较功能正常工作，但如果我将降序设置为true则不行。

var dataSortField:SortField = new SortField("y", false, false, true);
var dataSortField2:SortField = new SortField("x", false, true, true);

dataSortField2.compareFunction = 
    function sort(item1:Object, item2:Object):int {
        return -1 * (ObjectUtil.numericCompare(item1.x, item2.x));
    }

谁能告诉我为什么？

Answer 1

您不需要使用 true 或 false 来升序/降序，因为您有自定义compareFunction 。这是一个如何使用它的基本示例。

<?xml version="1.0"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark">
<fx:Script><![CDATA[
    import mx.collections.ArrayCollection;
    import mx.utils.ObjectUtil;
    import spark.collections.Sort;
    import spark.collections.SortField;

    private var arrayCollection:ArrayCollection = new ArrayCollection([
        {x:5, Name:"Adam Lee"},
        {x:2, Name:"Bryan Hobb"},
        {x:3, Name:"Claudia Toledo"},
        {x:7, Name:"Matt Brill"},
        {x:8, Name:"Justin Hinz"},
        {x:4, Name:"Bikram Dangol"}
    ])

    private function onAscendingButtonClick():void
    {
        var dataSortField2:SortField = new SortField();
        dataSortField2.compareFunction = sortAscendingCompareFunction;
        arrayCollection.sort = new Sort();
        arrayCollection.sort.fields = [dataSortField2];
        arrayCollection.refresh();
    }

    private function sortAscendingCompareFunction(item1:Object, item2:Object):int
    {
        return ObjectUtil.numericCompare(item1.x, item2.x);
    }

    private function sortDesscendingCompareFunction(item1:Object, item2:Object):int
    {
        return ObjectUtil.numericCompare(item2.x, item1.x);
    }

    private function onDescendingButtonClick():void
    {
        var dataSortField2:SortField = new SortField();
        dataSortField2.compareFunction = sortDesscendingCompareFunction;
        arrayCollection.sort = new Sort();
        arrayCollection.sort.fields = [dataSortField2];
        arrayCollection.refresh();
    }
    ]]>
</fx:Script>
<s:VGroup verticalCenter="0" horizontalCenter="0">
    <s:HGroup>
        <s:Button label="Sort Ascending" click="{onAscendingButtonClick()}"/>
        <s:Button label="Sort Descending" click="{onDescendingButtonClick()}"/>
    </s:HGroup>
    <s:Panel title="Sort using compareFunction" width="100%" backgroundColor="green">
        <s:DataGrid dataProvider="{arrayCollection}" sortableColumns="false" width="100%"/>
    </s:Panel>
</s:VGroup>
</s:Application>

Answer 2

如果您不想使用自定义compareFunction，那么您就可以实现升序/降序功能：

<?xml version="1.0"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark">
<fx:Script><![CDATA[
    import mx.collections.ArrayCollection;
    import mx.utils.ObjectUtil;
    import spark.collections.Sort;
    import spark.collections.SortField;

    private var arrayCollection:ArrayCollection = new ArrayCollection([
        {x:5, Name:"Adam Lee"},
        {x:2, Name:"Bryan Hobb"},
        {x:3, Name:"Claudia Toledo"},
        {x:7, Name:"Matt Brill"},
        {x:8, Name:"Justin Hinz"},
        {x:4, Name:"Bikram Dangol"}
    ])

    private function onAscendingButtonClick():void
    {
        var dataSortField2:SortField = new SortField("x", false, true);
        //dataSortField2.compareFunction = sortAscendingCompareFunction;
        arrayCollection.sort = new Sort();
        arrayCollection.sort.fields = [dataSortField2];
        arrayCollection.refresh();
    }

    private function sortAscendingCompareFunction(item1:Object, item2:Object):int
    {
        return ObjectUtil.numericCompare(item1.x, item2.x);
    }

    private function sortDesscendingCompareFunction(item1:Object, item2:Object):int
    {
        return ObjectUtil.numericCompare(item2.x, item1.x);
    }

    private function onDescendingButtonClick():void
    {
        var dataSortField2:SortField = new SortField("x", true, true);
        //dataSortField2.compareFunction = sortDesscendingCompareFunction;
        arrayCollection.sort = new Sort();
        arrayCollection.sort.fields = [dataSortField2];
        arrayCollection.refresh();
    }
    ]]>
</fx:Script>
<s:VGroup verticalCenter="0" horizontalCenter="0">
    <s:HGroup>
        <s:Button label="Sort Ascending" click="{onAscendingButtonClick()}"/>
        <s:Button label="Sort Descending" click="{onDescendingButtonClick()}"/>
    </s:HGroup>
    <s:Panel title="Sort without compareFunction" width="100%" backgroundColor="green">
        <s:DataGrid dataProvider="{arrayCollection}" sortableColumns="false" width="100%"/>
    </s:Panel>
</s:VGroup>
</s:Application>

Answer 3

您希望使用多个SortField。首先按升序顺序按第一个字段排序。如果它们相同，则按降序顺序按第二个字段排序。如果您使用compareFunction，则优先。在您的情况下，请不要使用compareFunction，因为true x 使用降序作为SortField。以下是一个例子：

<?xml version="1.0"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
           xmlns:s="library://ns.adobe.com/flex/spark">
<fx:Script><![CDATA[
    import mx.collections.ArrayCollection;
    import spark.collections.Sort;
    import spark.collections.SortField;

    private var arrayCollection:ArrayCollection = new ArrayCollection([
        {x:3, Name:"Claudia Toledo"},
        {x:5, Name:"Adam Lee"},
        {x:7, Name:"Adam Lee"},
        {x:2, Name:"Bryan Hobb"},
        {x:7, Name:"Matt Brill"},
        {x:4, Name:"Bikram Dangol"},
        {x:4, Name:"Adam Lee"},
        {x:9, Name:"Bikram Dangol"},
        {x:8, Name:"Justin Hinz"},
        {x:2, Name:"Bikram Dangol"}
    ]);

    private function onSortButtonClick():void
    {
        var dataSortField1:SortField = new SortField("Name", false, false);
        var dataSortField2:SortField = new SortField("x", true, true);
        arrayCollection.sort = new Sort();
        arrayCollection.sort.fields = [dataSortField1,dataSortField2];
        arrayCollection.refresh();
    }


    ]]>
</fx:Script>
<s:VGroup verticalCenter="0" horizontalCenter="0">
        <s:Button label="Sort Ascending Name and Descending x" click="{onSortButtonClick()}"/>
    <s:Panel title="Multiple Field Sort" width="100%" backgroundColor="green">
        <s:DataGrid dataProvider="{arrayCollection}" sortableColumns="false" width="100%"/>
    </s:Panel>
</s:VGroup>
</s:Application>

使用sortfield对多个属性上的arraycollection进行排序无法按预期工作

3 个答案: