Generic Adapter and generic Adapter

Generic Adapter and generic Adapter

Activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <ListView        android:id="@+id/lv_main_apps"        android:layout_width="match_parent"        android:layout_height="0dp"        android:layout_weight="1" >    </ListView></LinearLayout>

Item_app.xml

<?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="70dp"    android:minHeight="70dp"    android:orientation="horizontal"     android:gravity="center_vertical">    <ImageView        android:id="@+id/iv_item_icon"        android:layout_width="70dp"        android:layout_height="70dp"        android:src="@drawable/ic_launcher" />    <TextView        android:id="@+id/tv_item_name"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="TextView" /></LinearLayout>

AppInfo

package com.example.app3_listview;import android.graphics.drawable.Drawable;public class AppInfo {private Drawable icon;private String appName;private String packageName;public AppInfo(Drawable icon, String appName, String packageName) {super();this.icon = icon;this.appName = appName;this.packageName = packageName;}public AppInfo() {super();}public Drawable getIcon() {return icon;}public void setIcon(Drawable icon) {this.icon = icon;}public String getAppName() {return appName;}public void setAppName(String appName) {this.appName = appName;}public String getPackageName() {return packageName;}public void setPackageName(String packageName) {this.packageName = packageName;}@Overridepublic String toString() {return "AppInfo [icon=" + icon + ", appName=" + appName+ ", packageName=" + packageName + "]";}}

MainActivity

Package com. example. app3_listview; import java. util. arrayList; import java. util. list; import android. app. activity; import android. content. context; import android. content. intent; import android. content. pm. packageManager; import android. content. pm. resolveInfo; import android. graphics. drawable. drawable; import android. OS. bundle; import android. view. view; import android. widget. adapterView; import android. widget. li StView; import android. widget. toast; import com. example. adapter. base. commonBaseAdapter; import com. example. adapter. base. viewHolder; public class MainActivity extends Activity {private ListView lv_main_apps; private List <AppInfo> data; private MyAdapter adapter; @ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); // load the view-only one listviewsetContentView (R. layout. acti Vity_main); // obtain idlv_main_apps = (ListView) findViewById (R. id. lv_main_apps); // obtain data = getAllAppInfos (); // create adapteradapter = new MyAdapter (this, data, R. layout. item_app); // set the adapter to display lv_main_assist.setadapter (adapter); // set the click listener for each item (item) to lv_main_assist.setonitemclicklistener (new AdapterView. onItemClickListener () {@ Overridepublic void onItemClick (AdapterView <?> Parent, View view, int position, long id) {// subscript clicked by position // obtain the data AppInfo appInfo = data. get (position); String appName = appInfo. getAppName (); // display Toast. makeText (MainActivity. this, appName, 0 ). show () ;}}) ;}/ ** get the List of all application information in the mobile phone. AppInfo */protected List <AppInfo> getAllAppInfos () {List <AppInfo> list = new ArrayList <AppInfo> (); // obtain the application packgeManagerPackageManager packageManager = getPackageManager (); // create intentIntent intent = new Intent (); intent. setAction (Intent. ACTION_MAIN); intent. addCategory (Intent. CATEGORY_LAUNCHER); // obtain the List containing application information <ResolveInfo> ResolveInfos = packageManager. queryIntentActivities (intent, 0); // traverse for (ResolveInfo ri: ResolveInfos) {// obtain the package name String packageName = ri. activityInfo. packageName; // get the icon Drawable icon = ri. loadIcon (packageManager); // obtain the application name String appName = ri. loadLabel (packageManager ). toString (); // encapsulate the application information object AppInfo appInfo = new AppInfo (icon, appName, packageName); // Add it to listlist. add (appInfo);} return list;}/*** inherits the adapter class from CommonBaseAdapter */class MyAdapter extends CommonBaseAdapter <AppInfo> {public MyAdapter (Context context, final List <AppInfo> data, int layoutId) {super (context, data, layoutId, new Convert () {@ Overridepublic void convert (ViewHolder holder, int position) {AppInfo appInfo = data. get (position); holder. setText (R. id. TV _item_name, appInfo. getAppName ()). setImageDrawable (R. id. iv_item_icon, appInfo. getIcon ());}});}}}

CommonBaseAdapter

Package com. example. adapter. base; import java. util. list; import android. content. context; import android. view. view; import android. view. viewGroup; import android. widget. baseAdapter;/*** common baseAdapter */public abstract class CommonBaseAdapter <T> extends BaseAdapter {private Context context; private List <T> data; private int layoutId; public Convert convert; /*** sets the abstract method of View data, which is implemented by the specific adapter subclass */public interface Convert {void convert (ViewHolder holder, int position );} public CommonBaseAdapter (Context context, List <T> data, int layoutId, Convert convert) {this. context = context; this. data = data; this. layoutId = layoutId; this. convert = convert;} @ Overridepublic int getCount () {return data. size () ;}@ Overridepublic T getItem (int position) {return data. get (position) ;}@ Overridepublic long getItemId (int position) {return 0 ;}@ Overridepublic View getView (int position, View convertView, ViewGroup parent) {// obtain the Viewholder object ViewHolder holder = ViewHolder. getHolder (context, convertView, layoutId); // call the unimplemented abstract method to set data convert. convert (holder, position); // return convertViewreturn holder in holder. getConvertView ();}}

ViewHolder

Package com. example. adapter. base; import android. content. context; import android. graphics. drawable. drawable; import android. util. sparseArray; import android. view. view; import android. widget. imageView; import android. widget. textView;/*** common ViewHolder class */public class ViewHolder {// represents the view object private View itemConvertView of the current row; // used to replace Map <Integer, object> containers are more efficient than map private SparseArray <View> views; /*************************************** * *************************** to get the ViewHolder object context -- layoutId: this is used to construct the layout file * convertview: it is a reusable item Layout */public static ViewHolder getHolder (Context context, View convertView, int layoutId) {/*** if there is no reusable layout, you can create this class object. if there is one, you can get it through getTag **/if (convertView = null) {return new ViewHolder (context, layoutId);} else {ViewHolder holder = (ViewHolder) convertView. getTag (); return holder ;}}/*** constructor loads the layout file and saves the class tag, namely, viewholder, to itemConvertView */private ViewHolder (Context context, int layoutId) {this. itemConvertView = View. inflate (context, layoutId, null); this. itemConvertView. setTag (this); views = new SparseArray <View> () ;}/ *** get the current convertView */public View getConvertView () {return itemConvertView ;} /*************************** % * * ******************************* obtain the corresponding view object according to the view id * /public <T extends View> T getView (int viewId) {View view = views. get (viewId); if (view = null) {view = itemConvertView. findViewById (viewId); views. put (viewId, view);} return (T) view;} // *** set text data */public ViewHolder setText (int viewId, String text) {TextView textView = getView (viewId); textView. setText (text); return this;}/*** set drawable image */public ViewHolder setImageDrawable (int viewId, Drawable drawable) {ImageView imageView = getView (viewId); imageView. setImageDrawable (drawable); return this;}/*** set resource image */public ViewHolder setImageResource (int viewId, int resourceId) {ImageView imageView = getView (viewId); imageView. setImageResource (resourceId); return this ;}}

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