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;
  }
}

}