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;
  }
}

}