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一个适配器多种数据类型-android

adapter polymorphism android java

Richardweber32 · 技术社区 · 7 年前

不同之处。java文件用于显示同一事物的不同类型,因此从共享父对象继承,例如basicrunner extends runner和lollipoprunner extends runner。

适配器扩展了BaseAdapter,并重写getItem等的方法,但它们指定了一种返回类型;

public class RunnersAdapter extends BaseAdapter {
private static final String TAG = "RunnersAdapter";

//used in switch statement to decide which XML to inflate
private static final int LayoutTYPE_1 = 1;  
private static final int LayoutTYPE_2 = 2;
private static final int LayoutTYPE_3 = 3;
int layout = 2; //hard coded just for testing

@Override
public Runner getItem(int position) { //runner is superclass
    return mRunners.get(mKeys[position]);
}

有没有办法为每种类型的跑步者使用这个RunnerAdapter,或者我最好为每种类型制作一个不同的适配器?

编辑:

还有一些代码来说明我的意思:

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    LayoutInflater inflater = (LayoutInflater) mContext
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

if(layout == LayoutTYPE_1){ //LollipopView

            Runner runner = getItem(position); //should be a lollipopRunner!!

            gridView = inflater.inflate(R.layout.lollipopRunner, null); //use lollipopRunner XML
}else if(layout == LayoutTYPE_2){

            Runner runner = getItem(position);  //should be basicRunner!!

            gridView = inflater.inflate(R.layout.basicrunner, null); //use basic runner XML

2 回复 | 直到 7 年前

Sumit Jha 7 年前

BaseAdapter有几个方法可以重写,以便根据位置返回不同类型的视图。

        @Override
        public int getItemViewType(int position) {
            if (...) return 1;
            else if (...) return 2;
            else if (...) return 3;
            else return 4;
        }

        @Override
        public int getViewTypeCount() {
            return 4; //total number of different type of views 
        }


        @Override
        public View getView(int position, View view, ViewGroup viewGroup) {


            switch (getItemViewType(position)) {
                case 0:
                    if (view == null) {
                        view = mActivity.getLayoutInflater().inflate(R.layout.message_item_1, viewGroup, false);
                    }
                    break;
                case 1:
                    if (view == null) {
                        view = mActivity.getLayoutInflater().inflate(R.layout.message_item_1_media, viewGroup, false);
                    }
                    break;
                case 2:
                    if (view == null) {
                        view = mActivity.getLayoutInflater().inflate(R.layout.message_item_2, viewGroup, false);
                    }
                    break;
                case 3:
                    if (view == null) {
                        view = mActivity.getLayoutInflater().inflate(R.layout.message_item_2_media, viewGroup, false);
                    }
                    break;
            }
    }

编辑:

将数据馈送到适配器时,可以将其作为 List of Object

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    LayoutInflater inflater = (LayoutInflater) mContext
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

if(layout == LayoutTYPE_1){ //LollipopView

            // getItem(postion) will give you Object - downcast it as per the position.

            Runner runner = (LollipopRunner)(getItem(position)); //downcast to lollipopRunner

            gridView = inflater.inflate(R.layout.lollipopRunner, null); //use lollipopRunner XML
}else if(layout == LayoutTYPE_2){

            Runner runner = (BasicRunner)(getItem(position));  //downcasted to basic runner

        gridView = inflater.inflate(R.layout.basicrunner, null); //use basic runner XML

Klevin Delimeta 7 年前