Important controls for Android control many problems with the ListView solution

Knowledge overview

ListView is one of the most common controls in Android, and when the ListView and CheckBox, Button, and other controls are used together, there are a number of problems, such as a ListView entry that is not selectable, a ListView memory Overflow, a select-all, and a reverse selection.
1.

Content using the ListView to create a menu

Create a Fruit class

 Public  class Fruit {    PrivateString name;Private intimg Public Fruit(String name,intIMG) { This. name = name; This. img = img; } PublicStringGetName() {returnName } Public void SetName(String name) { This. name = name; } Public int getimg() {returnimg } Public void setimg(intIMG) { This. img = img; }}

Then create a Myfruitadapter

 Public  class myfruitadapter extends baseadapter{    PrivateList<fruit> Mdata;PrivateLayoutinflater Minflater;//Use an array to store the status of all checkboxes, checked to True, otherwise false    Private Boolean[] mmanagerallcheckedbox; Public Myfruitadapter(list<fruit> mdata, Layoutinflater minflater) { This. Mdata = Mdata; This. Minflater = Minflater; Mmanagerallcheckedbox =New Boolean[Mdata.size ()]; }/** * for * @param selected checkbox */     Public void setitemstate(intPosition) {Mmanagerallcheckedbox[position]=!mmanagerallcheckedbox[position];    Notifydatasetchanged (); } Public void Itemcheckedall(){ for(inti =0; I < mdata.size (); i++) {mmanagerallcheckedbox[i]=true;    } notifydatasetchanged (); } Public void Itemcheckedfan(){ for(inti =0; I < mdata.size ();        i++) {Mmanagerallcheckedbox[i]=!mmanagerallcheckedbox[i];    } notifydatasetchanged (); }@Override     Public int GetCount() {returnMdata.size (); }@Override     PublicObjectGetItem(intPosition) {returnPosition }@Override     Public Long Getitemid(intPosition) {returnPosition }@Override     PublicViewGetView(Final intPosition, View Convertview, ViewGroup parent) {Viewholder VH =NULL;if(convertview==NULL) {Convertview = Minflater.inflate (R.layout.fruit_list_item,NULL); VH =NewViewholder ();            Vh.checkbox = (CheckBox) Convertview.findviewbyid (R.id.item_fruit_checkbox);            Vh.imageview = (ImageView) Convertview.findviewbyid (R.id.item_fruit_imageview); Vh.textview = (TextView) Convertview.findviewbyid (R.id.item_fruit_textview);//Store VH as a label in convertConvertview.settag (VH); }Else{//convertview not be empty when not re-findviewbyid, directly call the stored VH, improve efficiencyVH = (Viewholder) convertview.gettag ();        } Fruit Fruit = Mdata.get (position);        Vh.imageView.setImageResource (Fruit.getimg ());        Vh.textView.setText (Fruit.getname ()); Vh.checkBox.setOnCheckedChangeListener (NewCompoundbutton.oncheckedchangelistener () {@Override             Public void oncheckedchanged(Compoundbutton Buttonview,BooleanisChecked) {mmanagerallcheckedbox[position]=ischecked; Notifydatasetchanged ();//Refresh DataLOG.D ("checkbox", position+"Status:"+ischecked);        }        }); Vh.checkBox.setChecked (Mmanagerallcheckedbox[position]);returnConvertview; }Private  class viewholder{CheckBox checkbox;        ImageView ImageView;    TextView TextView; }}

Finally create a myfruitactivity

 Public  class myfruitactivity extends Activity {    PrivateList<fruit> Mdata;PrivateLayoutinflater Minflater;PrivateListView Fruitlistview;PrivateMyfruitadapter Myfruitadapter;PrivateButton mheaderbtn;PrivateView Mheaderview;PrivateButton mfooterbtn;PrivateView Mfooterview;@Override    protected void onCreate(Bundle savedinstancestate) {Super. OnCreate (Savedinstancestate);        Setcontentview (R.layout.activity_my_fruit);        Fruitlistview = (ListView) Findviewbyid (R.id.fruit_list_view); Minflater = This. Getlayoutinflater ();        InitData (); Myfruitadapter =NewMyfruitadapter (Mdata,minflater);//Load layout files for entry and end entries, respectivelyMheaderview = Minflater.inflate (R.layout.listview_header_layout,NULL); Mfooterview = Minflater.inflate (R.layout.listview_footer_layout,NULL);//listview calls its method of increasing the end and end entries to load the Kinsoku entryFruitlistview.addheaderview (Mheaderview);        Fruitlistview.addfooterview (Mfooterview);        MHEADERBTN = (Button) Findviewbyid (R.id.header_button); MFOOTERBTN = (Button) Findviewbyid (R.id.footer_button);//Set the listener for the end-to-end button respectively, and their functions are all select and reverseMheaderbtn.setonclicklistener (NewView.onclicklistener () {@Override             Public void OnClick(View v)            {Myfruitadapter.itemcheckedall ();        }        }); Mfooterbtn.setonclicklistener (NewView.onclicklistener () {@Override             Public void OnClick(View v)            {Myfruitadapter.itemcheckedfan ();        }        }); Fruitlistview.setadapter (Myfruitadapter);//Set a click event for the ListView, and the corresponding checkbox will be selected whenever a view is selectedFruitlistview.setonitemclicklistener (NewAdapterview.onitemclicklistener () {@Override             Public void Onitemclick(adapterview<?> parent, view view,intPositionLongID) {the reason for//position minus 1 is that header entries are added to all the ListView entries .Myfruitadapter.setitemstate (position-1);    }        }); }//Initialize the data to be loaded into the ListView    Private void InitData() {Mdata =NewArraylist<> (); Fruit Apple =NewFruit ("Apple", r.mipmap.image); Fruit Pineapple =NewFruit ("Pineapple", r.mipmap.pk); Fruit pear =NewFruit ("Pear", R.MIPMAP.A_LOGO1); for(intI=0;i<4; i++) {mdata.add (Apple);            Mdata.add (pineapple);        Mdata.add (pear); }    }}

Fruit_list_item as a layout for each entry
Where focusable is used to prevent the click events of the checkbox's parent control from being absorbed by the checkbox

<linearlayout  xmlns: Android  = "http://schemas.android.com/apk/res/android"  android:orientation  =" horizontal " android:layout_margin  =" 15DP " android: Gravity  = "center_vertical"  android:layout_ Width  = "match_parent"  android:layout_heigh T  = "match_parent" ;     <checkbox  android:id  = "@+id/item_fruit_checkbox"  android:layout_ Width  = "wrap_content"  android:layout_height< /span>= "wrap_content"  android:focusable  =< Span class= "Hljs-value" > "false"  android:text  =  "Select fruit:" />     <ImageViewandroid:id="@+id/item_fruit_imageview"android:layout_width ="100DP"android:layout_height="100DP"/>                            <TextViewandroid:id="@+id/item_fruit_textview"android:layout_width ="Wrap_content"android:layout_height="wrap_content"/>                        </linearlayout>

Layout file

<Relativelayout xmlns:android="Http://schemas.android.com/apk/res/android"                Xmlns:tools="Http://schemas.android.com/tools"                Android:layout_width="Match_parent"                Android:layout_height="Match_parent"                Android:paddingleft="@dimen/activity_horizontal_margin"                Android:paddingright="@dimen/activity_horizontal_margin"                Android:paddingtop="@dimen/activity_vertical_margin"                Android:paddingbottom="@dimen/activity_vertical_margin"                Tools:context="Com.example.administrator.mywidget.MyFruitActivity">    <ListViewandroid:id="@+id/fruit_list_view"android:layout_width= "Match_parent" android:layout_height="Match_parent">                            </ListView></relativelayout>

Create a listview_header_layout as the first entry layout for the ListView

<?xml version= "1.0" encoding= "Utf-8"?><linearlayout xmlns:android="Http://schemas.android.com/apk/res/android"  Android:orientation="vertical"android:layout_width="Match_parent"  Android:layout_height="Match_parent">                                              <buttonandroid:id= "@+id/header_button"android:layout_width=" Wrap_content "android:layout_height=" Wrap_content "android:text=" Select All "/ >                                </linearlayout>

Create a trailing entry layout with a ListView

<?xml version= "1.0" encoding= "Utf-8"?><linearlayout  xmlns: Android  = "http://schemas.android.com/apk/res/android"  android:orientation  =" vertical " android:layout_width  =" match_parent " and Roid:layout_height  =;     <buttonandroid:id= "@+id/footer_button"android:layout_width=" Wrap_content "android:layout_height=" Wrap_content "android:text=" Reverse selection "/ >                                </linearlayout>

Operation Result:

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

Important controls for Android control many problems with the ListView solution