Android with handler for automatic switching of pages in Viewpager

In many e-commerce Web pages and apps have automatic switching of products to promote fast, feel very good experience, just today learning to use Viewpager, so also implemented a similar function of the demo.

Here are two of them:

To achieve an auto-play function of the Viewpager, to do the main has the following several parts:

• Implement a viewpageradapter to provide display content for Viewpager (e.g. two kitten pictures above)

public class Viewpageradapter extends Pageradapter {private list<view> mdata;public viewpageradapter (list< View> mdata) {this.mdata = Mdata;} @Overridepublic int GetCount () {return mdata.size ();} @Overridepublic boolean isviewfromobject (View arg0, Object arg1) {return arg0 = = arg1;} @Overridepublic Object Instantiateitem (viewgroup container, int position) {View v = mdata.get (position); Container.addview (v); return v;} @Overridepublic void Destroyitem (ViewGroup container, int position, object object) {//super.destroyitem (container, Position, object); Container.removeview (Mdata.get (position));}}

• Implement a Onpagechangelistener, so that after the page switch can prompt the current page location (for example, 3 dots in the lower left corner, red indicates the current page)

Private class Viewpagechangelistener implements Onpagechangelistener {@Overridepublic void onpagescrollstatechanged ( int arg0) {} @Overridepublic void onpagescrolled (int arg0, float arg1, int arg2) {}// Listen for page change events to change the viewindicator in the indicator picture @overridepublic void onpageselected (int arg0) {int len = Viewindicator.getchildcount (); for (int i = 0; i < len; ++i) Viewindicator.getchildat (i). Setbackgroundresource (R.drawable.tip_normal); Viewindicator.getchildat (arg0). Setbackgroundresource (R.drawable.tip_select);}}

• Implements a handler that modifies the UI after a certain interval (the currently displayed picture is switched to the next)

Private Handler Mhandler = new Handler () {public void Handlemessage (android.os.Message msg) {switch (msg.what) {case 1:int TotalCount = Pagers.size ();//autochangeviewpager.getchildcount (); int currentitem = Autochangeviewpager.getcurrentitem (); int toitem = CurrentItem + 1 = = TotalCount? 0:currentitem + 1; LOG.I (TAG, "totalcount:" + totalcount + "   currentitem:" + CurrentItem + "   toitem:" + toitem); autochangeviewpage R.setcurrentitem (Toitem, true);//Send a message every two seconds to toggle the picture this.sendemptymessagedelayed (1, 2000) in Viewpager;}};

The above 3 paragraphs are the main code, and in addition, you need to send a starting message in Onresume () and stop the automatic switching of the Viewpager page in OnStop ().

The complete code is as follows:

public class Mainactivity extends Activity {private static final String TAG = MainActivity.class.getSimpleName ();p rivate V Iewpager autochangeviewpager;//used to indicate the location of the currently displayed picture private LinearLayout viewindicator;//contains the picture to be displayed in Viewpager private List <View> pagers, @Overrideprotected void OnCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate) ; Setcontentview (r.layout.activity_main); Autochangeviewpager = (Viewpager) Findviewbyid (R.id.autoVP); viewIndicator = (linearlayout) Findviewbyid (r.id.vpindicator); Initadapter ();// Listen for the page change event to change the indicator image in Viewindicator autochangeviewpager.setonpagechangelistener (New Viewpagechangelistener ());} private void Initadapter () {//Picture resources to be shown in Viewpager int[] IMGs = {r.drawable.i1, r.drawable.i2, R.drawable.i3};//init Pagers;pagers = new arraylist<view> (); Linearlayout.layoutparams img_params = new Layoutparams (layoutparams.match_parent, layoutparams.match_parent); for ( int i = 0; i < imgs.length; ++i) {ImageView IV = new ImageView (this); Iv.setbackgroundresouRce (Imgs[i]); Iv.setlayoutparams (img_params); final int index = I;iv.setonclicklistener (new Onclicklistener () {// When the picture in Viewpager is clicked, jump to the new activity@overridepublic void OnClick (View v) {Intent i = new Intent (Mainactivity.this, Invokedactivity.class); I.putextra ("Name", "cat" + index); MainActivity.this.startActivity (i);}}); Pagers.add (iv);} Autochangeviewpager.setadapter (New Viewpageradapter (pagers));//init Indicatorlinearlayout.layoutparams Ind_params = new Layoutparams (layoutparams.wrap_content, layoutparams.wrap_content); for (int i = 0; i < imgs.length; ++i) {ImageVi EW IV = new ImageView (this), if (i = = 0) iv.setbackgroundresource (r.drawable.tip_select); Elseiv.setbackgroundresource ( R.drawable.tip_normal); Iv.setlayoutparams (ind_params); Viewindicator.addview (iv);}} @Overrideprotected void Onresume () {super.onresume ();//activity starts two seconds, sends a message, Used to switch the picture in Viewpager to the next mhandler.sendemptymessagedelayed (1, 2000);} @Overrideprotected void OnStop () {super.onstop ();//stop automatic switching of pictures in Viewpager Mhandler.removemEssages (1);} public class Viewpageradapter extends Pageradapter {private list<view> mdata;public viewpageradapter (list< View> mdata) {this.mdata = Mdata;} @Overridepublic int GetCount () {return mdata.size ();} @Overridepublic boolean isviewfromobject (View arg0, Object arg1) {return arg0 = = arg1;} @Overridepublic Object Instantiateitem (viewgroup container, int position) {View v = mdata.get (position); Container.addview (v); return v;} @Overridepublic void Destroyitem (ViewGroup container, int position, object object) {//super.destroyitem (container, Position, object); Container.removeview (Mdata.get (position));}} Private class Viewpagechangelistener implements Onpagechangelistener {@Overridepublic void onpagescrollstatechanged ( int arg0) {} @Overridepublic void onpagescrolled (int arg0, float arg1, int arg2) {}// Listen for page change events to change the viewindicator in the indicator picture @overridepublic void onpageselected (int arg0) {int len = Viewindicator.getchildcount (); for (int i = 0; i < len; ++i) Viewindicator.getchildat (i). setbackgRoundresource (R.drawable.tip_normal); Viewindicator.getchildat (arg0). Setbackgroundresource (R.drawable.tip_ Select);}} Private Handler Mhandler = new Handler () {public void Handlemessage (android.os.Message msg) {switch (msg.what) {case 1:int TotalCount = Pagers.size ();//autochangeviewpager.getchildcount (); int currentitem = Autochangeviewpager.getcurrentitem (); int toitem = CurrentItem + 1 = = TotalCount? 0:currentitem + 1; LOG.I (TAG, "totalcount:" + TotalCount + "CurrentItem:" + CurrentItem + "Toitem:" + toitem); autochangeviewpager.se Tcurrentitem (Toitem, true);//A message is sent every two seconds to toggle the picture this.sendemptymessagedelayed (1, 2000) in the Viewpager;}};}

The layout file is as follows: (The invokedactivity in the code above is very simple, omitted here)

<framelayout xmlns:android= "http://schemas.android.com/apk/res/android"    android:layout_width= "Match_ Parent "    android:layout_height=" match_parent ">    <android.support.v4.view.viewpager        android:id= "@+id/autovp"        android:layout_width= "match_parent"        android:layout_height= "match_parent"/>    < LinearLayout        android:id= "@+id/vpindicator"        android:layout_width= "match_parent"        android:layout_ height= "Wrap_content"        android:layout_gravity= "bottom"        android:orientation= "Horizontal"/></ Framelayout>