Preview the image library in android GridView. Check the upper right corner of the Multi-choice mode.

You can see that there is a need for beginners to: Use the GridView to preview the image library. In the multi-choice mode, check the upper right corner. (When you select multiple preview charts in the 4.0 image library, a blue border is added, which is actually a blue background.) The GridView has never been used in actual development and you just want to implement it, write a demo for beginners. Come First:
It is not complicated to implement. There are only two files. First, let's take a look at the GridView inheritance relationship: java. lang. object upload android. view. view every android. view. viewGroup uses android. widget. adapterView <T extends android. widget. adapter> logging android. widget. absListView uses android. widget. gridView we know that ListView has the single-choice mode and multi-choice mode [AbsListView. setChoiceMode (AbsListView. CHOICE_MODE_SINGLE/AbsListView. CHOICE_MODE_MULTIPLE_MODAL)] The GridView also supports multiple selection modes. Don't talk nonsense. I believe you know it too! Paste the code. main layout file: main. xml [html] <? Xml version = "1.0" encoding = "UTF-8"?> <LinearLayout xmlns: android = "http://schemas.android.com/apk/res/android" android: layout_width = "fill_parent" android: layout_height = "fill_parent"> <GridView android: id = "@ + id/gridview" android: layout_width = "fill_parent" android: layout_height = "wrap_content" android: columnWidth = "75dip" android: gravity = "center" android: horizontalSpacing = "2dip" android: numColumns = "4" android: verticalSpacing = "2dip"/> </ LinearLayout> main Activity: HomeActivity [java] package com. xyz. gridview; import java. util. hashMap; import java. util. map; import java. util. set; import android. app. activity; import android. content. context; import android. OS. bundle; import android. view. actionMode; import android. view. layoutInflater; import android. view. menu; import android. view. menuItem; import android. view. view; import android. view. view Group; import android. widget. absListView; import android. widget. absListView. layoutParams; import android. widget. absListView. multiChoiceModeListener; import android. widget. baseAdapter; import android. widget. checkable; import android. widget. frameLayout; import android. widget. gridView; import android. widget. imageView; import android. widget. listAdapter; import android. widget. textView; public class Hom EActivity extends Activity implements MultiChoiceModeListener {private GridView mGridView; private GridAdapter mGridAdapter; private TextView mActionText; private static final int MENU_SELECT_ALL = 0; private static final int completion = MENU_SELECT_ALL + 1; private Map <Integer, Boolean> mSelectMap = new HashMap <Integer, Boolean> (); private int [] mImgIds = new int [] {R. drawable. img_1, R. Drawable. img_2, R. drawable. img_3, R. drawable. img_4, R. drawable. img_5, R. drawable. img_6, R. drawable. img_7, R. drawable. img_8, R. drawable. img_9, R. drawable. img_1, R. drawable. img_2, R. drawable. img_3, R. drawable. img_4, R. drawable. img_5, R. drawable. img_6, R. drawable. img_7};/** Called when the activity is first created. * // @ Override public void onCreate (Bundle savedInstanceState) {super. onCreate (saved InstanceState); setContentView (R. layout. main); mGridView = (GridView) findViewById (R. id. gridview); mGridView. setChoiceMode (GridView. CHOICE_MODE_MULTIPLE_MODAL); mGridAdapter = new GridAdapter (this); mGridView. setAdapter (mGridAdapter); mGridView. setMultiChoiceModeListener (this);}/** Override MultiChoiceModeListener start **/@ Override public boolean onCreateActionMode (ActionMode mode, Menu menu) {// TODO Auto-generated method stub View v = LayoutInflater. from (this ). inflate (R. layout. actionbar_layout, null); www.2cto.com mActionText = (TextView) v. findViewById (R. id. action_text); mActionText. setText (formatString (mGridView. getCheckedItemCount (); mode. setCustomView (v); getMenuInflater (). inflate (R. menu. action_menu, menu); return true;} @ Override public boolean onPrepareActionMode (ActionMode Mode, Menu menu) {// TODO Auto-generated method stub menu. getItem (MENU_SELECT_ALL). setEnabled (mGridView. getCheckedItemCount ()! = MGridView. getCount (); return true ;}@ Override public boolean onActionItemClicked (ActionMode mode, MenuItem item) {// TODO Auto-generated method stub switch (item. getItemId () {case R. id. menu_select: for (int I = 0; I <mGridView. getCount (); I ++) {mGridView. setItemChecked (I, true); mSelectMap. put (I, true);} break; case R. id. menu_unselect: for (int I = 0; I <mGridView. getCount (); I ++) {mGri DView. setItemChecked (I, false); mSelectMap. clear ();} break;} return true;} @ Override public void onDestroyActionMode (ActionMode mode) {// TODO Auto-generated method stub mGridAdapter. policydatasetchanged () ;}@ Override public void onItemCheckedStateChanged (ActionMode mode, int position, long id, boolean checked) {// TODO Auto-generated method stub mActionText. setText (formatString (mGridView. ge TCheckedItemCount (); mSelectMap. put (position, checked); mode. invalidate ();}/** Override MultiChoiceModeListener end **/private String formatString (int count) {return String. format (getString (R. string. selection), count);} private class GridAdapter extends BaseAdapter {private Context mContext; public GridAdapter (Context ctx) {mContext = ctx ;}@ Override public int getCount () {// TODO Auto- Generated method stub return mImgIds. length ;}@ Override public Integer getItem (int position) {// TODO Auto-generated method stub return Integer. valueOf (mImgIds [position]);} @ Override public long getItemId (int position) {// TODO Auto-generated method stub return position;} @ Override public View getView (int position, view convertView, ViewGroup parent) {// TODO Auto-generated method stub GridI Tem item; if (convertView = null) {item = new GridItem (mContext); item. setLayoutParams (new LayoutParams (LayoutParams. FILL_PARENT, LayoutParams. FILL_PARENT);} else {item = (GridItem) convertView;} item. setImgResId (getItem (position); item. setChecked (mSelectMap. get (position) = null? False: mSelectMap. get (position); return item ;}} GridItem is a self-encapsulated class: GridItem. java [java] package com. xyz. gridview; import android. content. context; import android. util. attributeSet; import android. util. log; import android. view. layoutInflater; import android. view. view; import android. widget. checkable; import android. widget. imageView; import android. widget. relativeLayout; public class GridIte M extends RelativeLayout implements Checkable {private Context mContext; private boolean mChecked; private ImageView mImgView = null; private ImageView mSecletView = null; public GridItem (Context context) {this (context, null, 0);} public GridItem (Context context, AttributeSet attrs) {this (context, attrs, 0);} public GridItem (Context context Context, AttributeSet attrs, int defStyle) {super (context, Attrs, defStyle); // TODO Auto-generated constructor stub mContext = context; LayoutInflater. from (mContext ). inflate (R. layout. grid_item, this); mImgView = (ImageView) findViewById (R. id. img_view); mSecletView = (ImageView) findViewById (R. id. select) ;}@ Override public void setChecked (boolean checked) {// TODO Auto-generated method stub mChecked = checked; setBackgroundDrawable (checked? GetResources (). getDrawable (R. drawable. background): null); mSecletView. setVisibility (checked? View. VISIBLE: View. GONE) ;}@ Override public boolean isChecked () {// TODO Auto-generated method stub return mChecked ;}@ Override public void toggle () {// TODO Auto-generated method stub setChecked (! MChecked);} public void setImgResId (int resId) {if (mImgView! = Null) {mImgView. setBackgroundResource (resId) ;}} a layout referenced by this class: grid_item.xml [html] <? Xml version = "1.0" encoding = "UTF-8"?> <RelativeLayout xmlns: android = "http://schemas.android.com/apk/res/android" android: layout_width = "fill_parent" android: layout_height = "fill_parent"> <ImageView android: id = "@ + id/img_view" android: layout_width = "fill_parent" android: layout_height = "fill_parent" android: scaleType = "fitXY"/> <ImageView android: id = "@ + id/select" android: layout_width = "wrap_content" android: layout_height = "wrap_content" android: layout_alignParentRight = "true" android: Allow = "true" android: background = "@ drawable/icon_choice" android: visibility = "gone"/> </RelativeLayout>