以编程方式更改图层列表中的形状的颜色

Question

我试图以编程方式更改selectable_kachel_shape的颜色.这是xml文件:

kachel_ticked_style.xml

<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >


    <item>
        <shape
            android:id="@+id/selectable_kachel_shape"
            android:shape="rectangle" >
            <stroke
                android:width="5dp"
                android:color="@color/headrbar_color" />
        </shape>
    </item>
    <item>
        <rotate
            android:fromDegrees="45"
            android:pivotX="120%"
            android:pivotY="100%"
            android:toDegrees="45" >
            <shape android:shape="line" >
                <stroke
                    android:width="40dp"
                    android:color="@color/headrbar_color" />
            </shape>
        </rotate>
    </item>
    <item
        android:right="5dp"
        android:top="5dp">
        <bitmap
            android:gravity="top|right"
            android:src="@drawable/selectable_tiles_check" />
    </item>

</layer-list>

我在片段内调用以下代码

LayerDrawable layers = (LayerDrawable)  this.getActivity().getResources().getDrawable(R.drawable.kachel_ticked_style);

GradientDrawable shape = (GradientDrawable) (layers.findDrawableByLayerId(R.id.selectable_kachel_shape));
                       shape.setColor(this.getActivity().getResources().getColor(android.R.color.background_dark);

1.为什么我在shape.setColor中设置NullPointerException ？

2.如何以编程方式更改图层内部的形状内的颜色？

Answer 1

好的,我找到了答案,我只需将形状的id放在项目中,而不是形状为 kachel_ticked_style.xml:

<item 
    android:id="@+id/selectable_kachel_shape">
        <shape
             android:shape="rectangle" >
            <stroke
                android:width="5dp"
                android:color="@color/headrbar_color" />
        </shape>
    </item>

然后你可以改变调用shape.setColor的形状的颜色或调用shape.setStroke(strokeWidth,strokeColor)的笔触的颜色.