Android实现下拉展示条目效果

<?xml version="1.0" encoding="utf-8"? 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:background="#000000"
tools:context="com.example.a2_.MainActivity" 

<EditText
  android:id="@+id/et_input"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:textColor="#fff"
  android:text="请输入内容" / 

<ImageButton
  android:padding="6dp"
  android:background="@null"
  android:layout_alignRight="@id/et_input"
  android:id="@+id/ib"
  android:src="@mipmap/down_arrow"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content" / 
</RelativeLayout 

<?xml version="1.0" encoding="utf-8"? 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="5dp"
android:descendantFocusability="blocksDescendants"
android:orientation="horizontal" 

<ImageView

  android:src="@mipmap/user"
  android:id="@+id/iv_user"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content" / 

<TextView
  android:layout_weight="1"
  android:id="@+id/tv_data"
  android:text="100"
  android:textColor="#000000"
  android:gravity="center_horizontal"
  android:layout_width="0dp"
  android:layout_height="wrap_content" / 

<ImageButton
  android:background="@null"
  android:src="@mipmap/delete"
  android:id="@+id/iv_delete"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content" / 

</LinearLayout 

package com.example.a2_;
import android.graphics.drawable.ColorDrawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.PopupWindow;
import android.widget.TextView;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
private EditText et_input;
private PopupWindow popupWindow;
private ListView lv_list;
private ArrayList<String  data;
private MyAdapter myAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化控件
et_input = (EditText) findViewById(R.id.et_input);
ImageButton ib = (ImageButton) findViewById(R.id.ib);
//初始化数据源
initData();
//创建一个listView
lv_list = new ListView(this);
//给listview设置背景
lv_list.setBackgroundResource(R.mipmap.listview_background);
//给listview设置适配器
myAdapter = new MyAdapter();
lv_list.setAdapter(myAdapter);
//给listview设置条目点击事件
lv_list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?  parent, View view, int position, long id) {
//当点击到一个条目的时候,就把这个条目的内容显示在输入框中
et_input.setText(data.get(position));
popupWindow.dismiss();
}
});
//给按钮设置点击事件
ib.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//当点击下拉按钮时,显示列表选项
showPopup();
}
});
}
//初始化数据
private void initData() {
//创建一个集合,用来存储数据
data = new ArrayList< ();
//通过for循环创建数据
for (int i = 1;i<20;i++){
data.add(100+i+"");
}
}
//显示下拉的列表条目
private void showPopup() {
//创建PopupWindow对象
popupWindow = new PopupWindow(lv_list,et_input.getWidth(),500,true);
//为了在点击列表条目之外的区域能够让列表条目隐藏,为列表条目设置一个背景
popupWindow.setBackgroundDrawable(new ColorDrawable());
//让列表条目显示 并指定在哪个列表条目下展示
popupWindow.showAsDropDown(et_input);
}
//创建一个适配器
class MyAdapter extends BaseAdapter{
@Override
public int getCount() {
return data.size();
}
@Override
public String getItem(int position) {
return data.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
//判断convertView是否为空
if (convertView==null){
convertView = View.inflate(MainActivity.this,R.layout.lv_item,null);
}
//找到控件
TextView tv_data = (TextView) convertView.findViewById(R.id.tv_data);
ImageView iv_delete = (ImageView) convertView.findViewById(R.id.iv_delete);
//设置点击事件
iv_delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//删除集合里面的数据
data.remove(position);
//刷新页面
myAdapter.notifyDataSetChanged();
}
});
//获取数据
String data = getItem(position);
//设置数据
tv_data.setText(data);
return convertView;
}
}
}