Android Recyclerview to implement Drop-down list functionality _android

There are a lot of applications on the market, with a drop-down list of features, all the options are placed in the Drop-down list, when the user clicks on the selection, pop-up all the options, the user selects an item, the Drop-down list automatically hidden, many Drop-down lists are used ListView + Popupwindow to achieve, As Google has introduced a replacement for ListView's Recyclerview, this is a simple implementation:

Mainactivity.java

Package Com.jackie.countdowntimer; 
Import android.graphics.drawable.BitmapDrawable; 
Import Android.os.Bundle; 
Import Android.os.CountDownTimer; 
Import Android.support.design.widget.FloatingActionButton; 
Import Android.support.design.widget.Snackbar; 
Import android.support.v7.app.AppCompatActivity; 
Import Android.support.v7.widget.LinearLayoutManager; 
Import Android.support.v7.widget.RecyclerView; 
Import Android.support.v7.widget.Toolbar; 
Import Android.view.View; 
Import Android.widget.EditText; 
Import Android.widget.ImageButton; 
 
Import Android.widget.PopupWindow; 
Import java.util.ArrayList; 
 
Import java.util.List;  
  public class Mainactivity extends Appcompatactivity implements View.onclicklistener {private EditText mnumberedittext; 
  Private ImageButton Mselectimagebutton; 
  Private Popupwindow Mpopupwindow; 
  Private Recyclerview Mrecyclerview; 
  Private Recyclerviewadapter Mrecyclerviewadapter; 
 
  Private list<string> mnumberlist; 
  @Overrideprotected void OnCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate); 
    Setcontentview (R.layout.activity_main); 
    Toolbar Toolbar = (Toolbar) Findviewbyid (R.id.toolbar); 
 
    Setsupportactionbar (toolbar); 
    Floatingactionbutton fab = (Floatingactionbutton) Findviewbyid (R.id.fab); Fab.setonclicklistener (New View.onclicklistener () {@Override public void OnClick (view view) {Snac 
      Kbar.make (View, "Replace with your own action", Snackbar.length_long). Setaction ("action", null). Show (); 
 
    } 
    }); 
    Initialize Data Mnumberlist = new arraylist<> (); 
    for (int i = 0; i < i++) {Mnumberlist.add ("1000000" + i); 
    } Mnumberedittext = (edittext) Findviewbyid (R.id.number); 
    Mselectimagebutton = (ImageButton) Findviewbyid (R.id.select_number); 
  Mselectimagebutton.setonclicklistener (this); @Override public void OnClick (View v) {switch (V.getid ()) {case R.id.select_number:showselectnumberpopupwindow (); 
    Break 
 
    }/** * Pop-up select Number dialog box * * private void Showselectnumberpopupwindow () {Initrecyclerview (); 
    Mpopupwindow = new Popupwindow (Mrecyclerview, Mnumberedittext.getwidth ()-4, 200);   Mpopupwindow.setoutsidetouchable (TRUE); 
 
    Set external can be clicked Mpopupwindow.setbackgrounddrawable (New Bitmapdrawable ());    Mpopupwindow.setfocusable (TRUE); 
  Enable Popupwindow to get focus//display in the lower left corner of the input box Mpopupwindow.showasdropdown (Mnumberedittext, 2,-5); /** * Initialize Recyclerview, imitate ListView drop-down List effect * * private void Initrecyclerview () {Mrecyclerview = new Rec 
    Yclerview (this); 
    Set the layout manager mrecyclerview.setlayoutmanager (new Linearlayoutmanager (this)); 
 
    Mrecyclerview.setbackgroundresource (R.drawable.background); 
    Set adapter Mrecyclerviewadapter = new Recyclerviewadapter (this, mnumberlist); 
 
    Mrecyclerview.setadapter (Mrecyclerviewadapter); Set Click events 
    Mrecyclerviewadapter.setonitemclicklistener (New Recyclerviewadapter.onitemclicklistener () {@Override 
        public void Onitemclick (view view, int position) {Mnumberedittext.settext (Mnumberlist.get (position)); 
        Mnumberedittext.setselection (Mnumberedittext.gettext (). toString (). Length ()); 
      Mpopupwindow.dismiss (); 
 
    } 
    }); 
  Add a split line mrecyclerview.additemdecoration (this, divideritemdecoration.vertical_list) to the new Divideritemdecoration;  } 
 }

 recyclerviewadapter.java

Package Com.jackie.countdowntimer; 
Import Android.content.Context; 
Import Android.support.v7.widget.RecyclerView; 
Import Android.view.LayoutInflater; 
Import Android.view.View; 
Import Android.view.ViewGroup; 
Import Android.widget.ImageButton; 
 
Import Android.widget.TextView; 
 
Import java.util.List; 
 /** * Created by Jackie on 2015/12/18. * Recyclerview Adapter * * * public class Recyclerviewadapter extends Recyclerview.adapter<recyclerviewadapter.recycle 
  rviewholder> {private Onitemclicklistener monitemclicklistener; 
  Private context Mcontext; 
 
  Private list<string> mnumberlist; 
    Public Recyclerviewadapter (context context, list<string> numberlist) {this.mcontext = context; 
  This.mnumberlist = numberlist; 
  public interface Onitemclicklistener {void Onitemclick (view view, int position); } public void Setonitemclicklistener (Onitemclicklistener onitemclicklistener) {This.monitemclicklistener = OnIt EmclicklisTener; 
    @Override public Recyclerviewadapter.recyclerviewholder Oncreateviewholder (viewgroup parent, int viewtype) { Recyclerviewholder holder = new Recyclerviewholder (Layoutinflater.from (Mcontext). Inflate (R.layout.number_item, 
    Parent, false)); 
  return holder; @Override public void Onbindviewholder (final recyclerviewadapter.recyclerviewholder holder, final int position) 
    {Holder.numberTextView.setText (Mnumberlist.get (position)); If a callback is set, set the Click event if (Monitemclicklistener!= null) {Holder.numberTextView.setOnClickListener (new view.oncli Cklistener () {@Override public void OnClick (View v) {Monitemclicklistener.onitemclick (Holde 
        R.itemview, Holder.getlayoutposition ()); 
    } 
      }); Holder.deleteImageButton.setOnClickListener (New View.onclicklistener () {@Override public void Oncl 
        Ick (View v) {mnumberlist.remove (position); Notification Refresh Notifyitemremoved (position); 
  } 
    }); 
  @Override public int GetItemCount () {return mnumberlist.size (); 
    The public class Recyclerviewholder extends Recyclerview.viewholder {TextView numbertextview; 
 
    ImageButton Deleteimagebutton; 
      Public Recyclerviewholder (View Itemview) {super (Itemview); 
      Numbertextview = (TextView) Itemview.findviewbyid (R.id.number_item); 
    Deleteimagebutton = (ImageButton) Itemview.findviewbyid (r.id.number_item_delete);  } 
  } 
}

 divideritemdecoration.java

Package Com.jackie.countdowntimer; * * Copyright (C) 2014 the Android Open Source Project * Licensed under the Apache License, Version 2.0 (the "Lic 
 Ense "); 
 * Limitations under the License. 
* * Import Android.content.Context; 
Import Android.content.res.TypedArray; 
Import Android.graphics.Canvas; 
Import Android.graphics.Rect; 
Import android.graphics.drawable.Drawable; 
Import Android.support.v7.widget.LinearLayoutManager; 
Import Android.support.v7.widget.RecyclerView; 
 
Import Android.view.View; /** * This class are from the V7 samples of the Android SDK. 
 It ' s not by me! 
 * <p/> * License above for details. * * public class Divideritemdecoration extends Recyclerview.itemdecoration {private static final int[] Attrs = new I nt[]{Android. 
 
  R.attr.listdivider}; 
 
  public static final int horizontal_list = linearlayoutmanager.horizontal; 
 
  public static final int vertical_list = linearlayoutmanager.vertical; Private DrawabLe Mdivider; 
 
  private int morientation; Public Divideritemdecoration (context context, int orientation) {Final TypedArray a = Context.obtainstyledattributes ( 
    ATTRS); 
    Mdivider = a.getdrawable (0); 
    A.recycle (); 
  SetOrientation (orientation); public void setorientation (int orientation) {If orientation!= horizontal_list && Orientation!= VER 
    Tical_list) {throw new IllegalArgumentException ("Invalid orientation"); 
  } morientation = orientation; @Override public void OnDraw (Canvas C, recyclerview parent) {if (morientation = = vertical_list) {D 
    Rawvertical (c, parent); 
    else {Drawhorizontal (c, parent); 
    } public void Drawvertical (Canvas C, Recyclerview parent) {Final int left = Parent.getpaddingleft (); 
 
    Final int right = Parent.getwidth ()-parent.getpaddingright (); 
    Final int childcount = Parent.getchildcount (); 
for (int i = 0; i < ChildCount; i++) {      Final View child = Parent.getchildat (i); 
      Android.support.v7.widget.RecyclerView v = new Android.support.v7.widget.RecyclerView (Parent.getcontext ()); 
      Final Recyclerview.layoutparams params = (recyclerview.layoutparams) child.getlayoutparams (); 
      Final int top = Child.getbottom () + Params.bottommargin; 
      final int bottom = top + mdivider.getintrinsicheight (); 
      Mdivider.setbounds (left, top, right, bottom); 
    Mdivider.draw (c); 
    } public void Drawhorizontal (Canvas C, Recyclerview parent) {Final int top = Parent.getpaddingtop (); 
 
    final int bottom = Parent.getheight ()-Parent.getpaddingbottom (); 
    Final int childcount = Parent.getchildcount (); 
      for (int i = 0; i < ChildCount. i++) {final View child = Parent.getchildat (i); 
      Final Recyclerview.layoutparams params = (recyclerview.layoutparams) child.getlayoutparams (); 
      Final int left = Child.getright () + Params.rightmargin; Final int right =Left + mdivider.getintrinsicheight (); 
      Mdivider.setbounds (left, top, right, bottom); 
    Mdivider.draw (c); @Override public void Getitemoffsets (Rect outrect, int itemposition, Recyclerview parent) {if (Morien 
    tation = = vertical_list) {outrect.set (0, 0, 0, mdivider.getintrinsicheight ()); 
    else {outrect.set (0, 0, mdivider.getintrinsicwidth (), 0); 

 } 
  } 
}

The effect chart is as follows:

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