PopupWindow下拉列表

效果图

步骤：

1.画出编辑框的布局、popupWindow的布局、popupWindow中listview每行的布局

2.new一个PopupWindow对象，设置其属性

3.定义一个BaseAdapter的继承类，将数据添加到ListView中，最后添加监听事件

*编辑框的布局

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    tools:context="org.mobiletrain.a7_4popupwindow.MainActivity">

    <EditText
        android:id="@+id/et"
        android:layout_width="300dp"
        android:layout_height="48dp"
        android:hint="请输入用户名"/>

    <ImageView
        android:id="@+id/show_pw"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@id/et"
        android:onClick="showPw"
        android:src="@drawable/down_arrow"/>
</RelativeLayout>

*popupWindow中的布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical">

    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></ListView>
</LinearLayout>

*popupWindow中的listview中每个元素的布局

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="48dp">

    <ImageView
        android:id="@+id/userface"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:padding="12dp"
        android:src="@drawable/user"/>

    <TextView
        android:id="@+id/username"
        android:layout_width="wrap_content"
        android:layout_height="48dp"
        android:layout_centerInParent="true"
        android:gravity="center"
        android:text="username"/>

    <ImageView
        android:id="@+id/delete"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:layout_alignParentRight="true"
        android:padding="12dp"
        android:src="@drawable/delete"/>
</RelativeLayout>

public class MainActivity extends AppCompatActivity {

    private EditText et;
    private List<String> list;
    private PopupWindow pw;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        et = ((EditText) findViewById(R.id.et));
    }

    public void showPw(View view) {
        //1.PopupWindow即将显示的布局
        //2.popupwindow的宽度
        //3.popupwindow的高度
        View contentView = LayoutInflater.from(this).inflate(R.layout.pw_layout, null);
        initListView(contentView);
        pw = new PopupWindow(contentView, et.getWidth(), 400);
        //设置当点击其他区域时关闭PopupWindow
        pw.setOutsideTouchable(true);
        pw.setBackgroundDrawable(new BitmapDrawable());
        //设置让PopupWindow获取焦点，如果不设置，在PW打开的情况下点击后退按钮会直接退出应用
        pw.setFocusable(true);

        //显示在某一个控件的下方，后面两个参数表示x,y轴 的偏移量
        pw.showAsDropDown(et, (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, -16, getResources().getDisplayMetrics()), 0);
    }

    //初始化popupWindow中的listview
    private void initListView(View contentView) {
        ListView listView = (ListView) contentView.findViewById(R.id.lv);
        list = getData();
        MyAdapter adapter = new MyAdapter(this, list);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                et.setText(list.get(position));
                //关闭弹出框
                pw.dismiss();
            }
        });
    }

    private List<String> getData() {
        List<String> list = new ArrayList<>();
        for (int i = 0; i < 30; i++) {
            list.add("李四：" + i);
        }
        return list;
    }
}

public class MyAdapter extends BaseAdapter {
    private Context context;
    private List<String> list;
    private LayoutInflater inflater;

    public MyAdapter(Context context, List<String> list) {
        this.context = context;
        this.list = list;
        inflater = LayoutInflater.from(context);
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

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

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.listview_item, null);
            holder = new ViewHolder();
            holder.delete = (ImageView) convertView.findViewById(R.id.delete);
            holder.username = (TextView) convertView.findViewById(R.id.username);
            convertView.setTag(holder);
        }else{
            holder = (ViewHolder) convertView.getTag();
        }
        holder.username.setText(list.get(position));
        holder.delete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                list.remove(position);
                notifyDataSetChanged();
            }
        });
        return convertView;
    }
    class ViewHolder{
        TextView username;
        ImageView delete;
    }
}