Android 13th Lesson--baseadapter

Baseadapter It takes four methods to create such an object. int GetCount (); Object getItem (int position); Long Getitemid (int position); View GetView (int position, view Convertview, ViewGroup parent), (1) The number of items in the list (2) returns the list contents of the value (3) Gets the ID of the list item at postion (4) The component in the list item

 PackageCom.example.baseadapter;Importandroid.app.Activity;ImportAndroid.graphics.Color;ImportAndroid.os.Bundle;ImportAndroid.view.View;ImportAndroid.view.ViewGroup;ImportAndroid.widget.BaseAdapter;ImportAndroid.widget.ImageView;Importandroid.widget.LinearLayout;ImportAndroid.widget.ListView;ImportAndroid.widget.TextView; Public classMainactivityextendsActivity {ListView mylist; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main); MyList=(ListView) Findviewbyid (r.id.mylist); Baseadapter Adapter=NewBaseadapter () {@Override Public intGetCount () {return40; } @Override PublicObject GetItem (intposition) {                return NULL; } @Override Public LongGetitemid (intposition) {                returnposition; } @Override PublicView GetView (intposition, View Convertview, ViewGroup parent) {                //Create a LinearLayout and add two components to itLinearLayout line=NewLinearLayout (mainactivity. This); Line.setorientation (0); ImageView Image=NewImageView (mainactivity. This);                Image.setimageresource (R.drawable.ic_launcher); TextView TextView=NewTextView (mainactivity. This); Textview.settext ("First" + (position+1) + "list items"); Textview.settextsize (20);                Textview.settextcolor (color.red);                Line.addview (image);                                Line.addview (TextView); //Returning LinearLayout instances                returnLine ;        }                                };    Mylist.setadapter (adapter); }    }

<LinearLayoutxmlns: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:orientation= "vertical">   <ListViewAndroid:id= "@+id/mylist"Android:layout_width= "Match_parent"Android:layout_height= "Wrap_content"     /></LinearLayout>

Baseadapter is implemented by writing its own default method to implement the ListView

So his part of the layout is not written in XML, but in the activity.