自定义公用Adapter适配器--回调机制

1.回调：我的理解是，一个类A实现一个接口CallBack（该接口可以是B类的内部接口，也可以是独立的接口），类A包含类B的引用b,类B有参数为callBack的方法或构造函数，最后类A调用B中的方法或构造函数，当类B触发某事件即可调用类A中CallBack的方法，最后将操作结果返回给类A，此为回调。

2.例子：自定义公用Adapter适配器

（1）类A：LActivity

public class LActivity extends BaseActivity implements View.OnClickListener,LAdepter.LCallBack{

    Context mContext;
    private ListView listView;
    private LAdepter lAdepter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.list_item_lenita_item);  //layout,其包含一个ListView
        initData();
    }

    private void initData(){
        mContext = this;
        String[] s = new String[3];
        s[0] = "first line";
        s[1] = "second line";
        s[2] = "third line";
        lAdepter = new LAdepter(mContext,LActivity.this,s);
        listView = (ListView)findViewById(R.id.lv_lenita);   //ListView
        listView.setAdapter(lAdepter);
    }

    @Override
    public void onClick(View view) {
       }

    @Override
    public ComponentName getBroadcastComponent() {
        return getComponentName();
    }

    @Override
    public void answer(String str) {
        LogUtil.log("test","call back answer = "+ str);  //具体的返回内容看类B给什么String
    }
}

(2)类B：LAdepter

public class LAdepter extends BaseAdapter {
    LCallBack lCallBack;
    private String[] strings;
    private Context mContext;

    public LAdepter(Context context,LCallBack lCallBack,String[] strings){
        this.lCallBack = lCallBack;
        this.strings = strings;
        mContext = context;
    }

    @Override
    public int getCount() {
        return strings.length;
    }

    @Override
    public String getItem(int i) {
        return strings[i];
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        if(view == null){
            view = LayoutInflater.from(mContext).inflate(R.layout.list_item_spinner, null); //自定义的ListView样式
            view.setTag(R.id.tv_list_item, view.findViewById(R.id.tv_list_item));
        }
        String content = getItem(i);
        TextView tv_list_item = (TextView) view.getTag(R.id.tv_list_item);
        tv_list_item.setText(content);
        tv_list_item.setOnClickListener(onClickListener);  //条目点击监听
        tv_list_item.setTag(i);
        return view;
    }

    View.OnClickListener onClickListener = new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            int position = (int)view.getTag();
            lCallBack.answer(getItem(position));  //回调
        }
    };

    public interface LCallBack {
        public void answer(String str);  //类B的内部接口
    }
}

（3） list_item_lenita_item.xml 和 list_item_spinner.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">
    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/lv_lenita"
        android:divider="@null">
    </ListView>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/layout_city_list">
   <TextView
       android:id="@+id/tv_list_item"
       android:layout_width="match_parent"
       android:layout_height="40dp"
       android:text="test"
       android:textSize="17.7dp"
       android:textColor="@color/black_word"
       android:gravity="center_vertical"
       android:paddingLeft="20dp"/>
</LinearLayout>

自定义公用Adapter适配器--回调机制

猜你喜欢