Android RecyclerView实现下拉列表功能

现在市面上的很多的应用，都带有下拉列表的功能，将所有选项都放在下拉列表中，当用户点击选择的时候，弹出所有的选项，用户选择一项后，下拉列表自动隐藏，很多下拉列表都是用listview + popupwindow来实现的，由于google推出了替代listview的recyclerview，所以简单实现一下：

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; 
 
  @override 
  protected 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) { 
        snackbar.make(view, "replace with your own action", snackbar.length_long) 
            .setaction("action", null).show(); 
      } 
    }); 
 
    //初始化数据 
    mnumberlist = new arraylist<>(); 
    for (int i = 0; i < 30; 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; 
    } 
  } 
 
  /** 
   * 弹出选择号码的对话框 
   */ 
  private void showselectnumberpopupwindow() { 
    initrecyclerview(); 
 
    mpopupwindow = new popupwindow(mrecyclerview, mnumberedittext.getwidth() - 4, 200); 
    mpopupwindow.setoutsidetouchable(true);   // 设置外部可以被点击 
    mpopupwindow.setbackgrounddrawable(new bitmapdrawable()); 
 
    mpopupwindow.setfocusable(true);    // 使popupwindow可以获得焦点 
    // 显示在输入框的左下角 
    mpopupwindow.showasdropdown(mnumberedittext, 2, -5); 
  } 
 
  /** 
   * 初始化recyclerview，模仿listview下拉列表的效果 
   */ 
  private void initrecyclerview(){ 
    mrecyclerview = new recyclerview(this); 
    //设置布局管理器 
    mrecyclerview.setlayoutmanager(new linearlayoutmanager(this)); 
    mrecyclerview.setbackgroundresource(r.drawable.background); 
 
    //设置adapter 
    mrecyclerviewadapter = new recyclerviewadapter(this, mnumberlist); 
    mrecyclerview.setadapter(mrecyclerviewadapter); 
 
    //设置点击事件 
    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(); 
      } 
    }); 
 
    //添加分割线 
    mrecyclerview.additemdecoration(new divideritemdecoration(this, divideritemdecoration.vertical_list)); 
  } 
 } 

 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.recyclerviewholder> { 
  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 = onitemclicklistener; 
  } 
 
  @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)); 
    // 如果设置了回调，则设置点击事件 
    if (monitemclicklistener != null) { 
      holder.numbertextview.setonclicklistener(new view.onclicklistener() { 
        @override 
        public void onclick(view v) { 
          monitemclicklistener.onitemclick(holder.itemview, holder.getlayoutposition()); 
        } 
      }); 
    } 
 
    holder.deleteimagebutton.setonclicklistener(new view.onclicklistener() { 
      @override 
      public void onclick(view v) { 
        mnumberlist.remove(position); 
        //通知刷新 
        notifyitemremoved(position); 
      } 
    }); 
  } 
 
  @override 
  public int getitemcount() { 
    return mnumberlist.size(); 
  } 
 
  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 "license"); 
 * 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 is from the v7 samples of the android sdk. it's not by me! 
 * <p/> 
 * see the license above for details. 
 */ 
public class divideritemdecoration extends recyclerview.itemdecoration { 
 
  private static final int[] attrs = new int[]{ 
      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 != vertical_list) { 
      throw new illegalargumentexception("invalid orientation"); 
    } 
    morientation = orientation; 
  } 
 
  @override 
  public void ondraw(canvas c, recyclerview parent) { 
    if (morientation == vertical_list) { 
      drawvertical(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 (morientation == vertical_list) { 
      outrect.set(0, 0, 0, mdivider.getintrinsicheight()); 
    } else { 
      outrect.set(0, 0, mdivider.getintrinsicwidth(), 0); 
    } 
  } 
} 

效果图如下：

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