Android learning notes: view the usage of GridView, androidgridview

Android learning notes: view the usage of GridView, androidgridview

(1) The layout creation code is as follows:

<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:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <GridView        android:id="@+id/gridView"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:layout_alignParentLeft="true"        android:layout_alignParentRight="true"        android:layout_alignParentTop="true"        android:numColumns="3" >    </GridView></RelativeLayout>

(2) Use the layout in the MainActivity class

Package com. example. layoutstudy; import android. OS. bundle; import android. app. activity; import android. view. menu; import android. view. view; import android. view. viewGroup; import android. widget. adapter; import android. widget. adapterView; import android. widget. adapterView. onItemClickListener; import android. widget. adapterViewFlipper; import android. widget. baseAdapter; import android. widget. gridView; import andro Id. widget. imageView; import android. widget. toast; public class MainActivity extends Activity {private GridView; private ImageAdapter adapter; @ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main); gridView = (GridView) this. findViewById (R. id. gridView); adapter = new ImageAdapter (); // sets an adapter gridView. setAdapter (adap Ter);/** create a click event. When you click an image, its position is displayed */gridView. setOnItemClickListener (new OnItemClickListener () {@ Overridepublic void onItemClick (AdapterView <?> Parent, View view, int position, long id) {Toast. makeText (MainActivity. this, "-->" + position, 1 ). show () ;}}) ;}// define the image resource private int [] images = {R. drawable. r1, R. drawable. r2, R. drawable. r3, R. drawable. r4, R. drawable. r5, R. drawable. r6, R. drawable. r7, R. drawable. r8};/** adapter definition, which must inherit BaseAdapter */public class ImageAdapter extends BaseAdapter {public ImageAdapter () {}@ Overridepublic int getCount () {return images. length ;}@ Overridepublic Object getItem (int position) {return images [position] ;}@ Overridepublic long getItemId (int position) {return position ;}@ Overridepublic View getView (int position, view convertView, ViewGroup parent) {/** 1. manually create an object 2. load xml file */ImageView imageView = null; if (convertView = null) {imageView = new ImageView (MainActivity. this);} else {imageView = (ImageView) convertView;} // you can specify the height of the sub-Image view displayed in the GridView. setLayoutParams (new GridView. layoutParams (200,200); imageView. setScaleType (ImageView. scaleType. CENTER_CROP); imageView. setPadding (30, 20, 20, 20); imageView. setImageResource (images [position]); return imageView; }}@ Overridepublic boolean onCreateOptionsMenu (Menu menu) {getMenuInflater (). inflate (R. menu. main, menu); return true ;}}

(3) The running effect is as follows: