Android Adapter (Adapter), viewer (Observer) mode

Adapter (Adapter) Details: http://blog.csdn.net/jjwwmlp456/article/details/39893723

The Observer (Observer) Details: http://blog.csdn.net/jjwwmlp456/article/details/39967021

Adapterview system

adapter is used in Adapterview

Adapter system

Baseadapter realizes the Spinneradapter, ListAdapter

In this form, the adapter mode is used, and here is the interface adapter

Viewer (Observer) mode

Methods for registering and deserializing datasetobserver are defined in adapter

Public interface Adapter {      void Registerdatasetobserver (Datasetobserver observer);    VOID Unregisterdatasetobserver (Datasetobserver observer);    ...}

Public abstract class Datasetobserver {public    void onChanged () {        //does nothing    } public    void Oninvalidat Ed () {        //Do Nothing    }}

public abstract class Baseadapter implements ListAdapter, Spinneradapter {private final    Datasetobservable mdatasetobservable = new datasetobservable ();    public void Registerdatasetobserver (Datasetobserver observer) {MDATASETOBSERVABLE.REGISTEROBSERVER (Observer); } public void Unregisterdatasetobserver (Datasetobserver observer) {Mdatasetobservable.unregisterobserver (observ    ER);    } public void Notifydatasetchanged () {mdatasetobservable.notifychanged ();    } public void notifydatasetinvalidated () {mdatasetobservable.notifyinvalidated (); }    ...}

public class Datasetobservable extends observable<datasetobserver> {public void n                Otifychanged () {synchronized (mobservers) {for (int i = Mobservers.size ()-1; I >= 0; i--) {            Mobservers.get (i). onChanged (); }}} public void notifyinvalidated () {synchronized (mobservers) {for (int i = Mobservers . Size ()-1; I >= 0;            i--) {mobservers.get (i). oninvalidated (); }        }    }}

Public abstract class Observable<t> {protected final arraylist<t> mobservers = new arraylist<t> (); public void Registerobserver (T observer) {if (Observer = = null) {throw new IllegalArgumentException (        "The observer is null."); } synchronized (Mobservers) {if (Mobservers.contains (Observer)) {throw new illegalstatee            Xception ("Observer" + Observer + "is already registered.");        MOBSERVERS.ADD (Observer); }} public void Unregisterobserver (T observer) {if (Observer = = null) {throw new illegalargument        Exception ("The Observer is null.");            } synchronized (mobservers) {int index = MOBSERVERS.INDEXOF (Observer);            if (index = =-1) {throw new IllegalStateException ("Observer" + Observer + "is not registered.");        } mobservers.remove (index);     }} public void UnregisterAll () {   Synchronized (mobservers) {mobservers.clear (); }    }}

Datasetobserver Observer (observation data set: Change onchanged, invalid oninvalidated)

Observable processing observers (add, remove, register, anti-registration)

Datasetobservable extends Observable<datasetobserver> added two ways to change and invalidate notification data

In the Adapterview

Class Adapterdatasetobserver extends Datasetobserver {private parcelable minstancestate = null;            @Override public void onChanged () {mdatachanged = true;            Molditemcount = Mitemcount;            Mitemcount = Getadapter (). GetCount ();            Detect the case where a cursor is previously invalidated have//been repopulated with new data. if (AdapterView.this.getAdapter (). Hasstableids () && minstancestate! = null && mOl                Ditemcount = = 0 && mitemcount > 0) {AdapterView.this.onRestoreInstanceState (minstancestate);            Minstancestate = null;            } else {remembersyncstate ();            } checkfocus ();        Requestlayout ();            } @Override public void oninvalidated () {mdatachanged = true; if (AdapterView.this.getAdapter (). Hasstableids ()) {//Remember the curRent state for the case where we hosting activity is being//stopped and later restarted m            Instancestate = AdapterView.this.onSaveInstanceState ();            }//Data is invalid so we should reset our state molditemcount = Mitemcount;            Mitemcount = 0;            Mselectedposition = invalid_position;            Mselectedrowid = invalid_row_id;            Mnextselectedposition = invalid_position;            Mnextselectedrowid = invalid_row_id;            Mneedsync = false;            Checkfocus ();        Requestlayout ();        } public void Clearsavedstate () {minstancestate = null; }    }

Custom Adapterdatasetobserver, called Requestlayout () in both implementations, to reset the layout

The process by which the entire observation data changes resulting in an interface change:
1. Customize the Adapterdatasetobserver in the Adapterview system and register (i.e. add observer to observable).

2. After calling Adapter.notifydatasetchanged (), the internal execution of observable's notifychanged (),

The onchanged () of each observer will be executed, and the effect of the update interface is achieved.

notifydatasetinvalidated

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Android Adapter (Adapter), viewer (Observer) mode