Android實戰技巧：Dialog

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轉：http://blog.csdn.net/hitlion2008/article/details/7567549#t0

Dialog是任何系統都必須有的一個控制項，作為次要視窗，用於顯示一些訊息，或請求使用者採取一引起操作等。

在Android中也不例外，基本使用可能參看文檔。

使用時的注意事項

1. BACK鍵能取消掉對話方塊(dismiss)，但是卻不會觸發其onOkey和onCancel回調介面，所以如果你的對話方塊會改某些狀態，一定要注意還有第三種方式取消對話方塊。

2. 盡量少用模態對話方塊(Model dialog)，如果Dialog.setCancellable(false)，就變成了一個模態對話方塊，除了程式內部把其Dismiss，否則按什麼鍵都無法將其取消。這是極差的使用者體驗，對話方塊本身就是一種幹擾，再無法取消會把使用者搞瘋的。所以除非特別有必要，也即當執行某個操作時不希望被打破，才可以使用模態對話方塊。

3. 盡量少用對話方塊，它對使用者是一種幹擾，除非需要使用者做操作，或者做出選擇。通常的一般性的通知用Toast或者Notification就足夠了。

4. 不要使用對話方塊風格的Activity，也即把Activity變成一個對話方塊。因為這樣是自已定義的布局，與系統Dialog的風格可能會不一致。最嚴重的是當系統風格發生變化，Dialog的子類會變化，但Activity式的對話方塊就不會變化。可以在ICS中找一找Activity對話方塊，你會發現其OK是在左邊，而ICS中系統Dialog的OK都是在右邊的。

5. 盡量保證Dialog對象活在Activity的生命週期之內，也即至多是在onCreate()和onDestroy()之間。

6. 要想到和測試到Activity在其Dialog.dismiss()之前死掉的情況。因為Activity必須依附於某個正在顯示的Activity執行個體，當顯示和取消的時候其Activity執行個體必須存在，否則就會有"IllegalArgumentException: View not attached to window manager"。

05-15 02:45:26.320: E/AndroidRuntime(1161): java.lang.IllegalArgumentException: View not attached to window manager05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.view.WindowManagerImpl.findViewLocked(WindowManagerImpl.java:355)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.view.WindowManagerImpl.removeView(WindowManagerImpl.java:200)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.view.Window$LocalWindowManager.removeView(Window.java:432)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.app.Dialog.dismissDialog(Dialog.java:278)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.app.Dialog.access$000(Dialog.java:71)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.app.Dialog$1.run(Dialog.java:111)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.app.Dialog.dismiss(Dialog.java:268)05-15 02:45:26.320: E/AndroidRuntime(1161):     at com.hilton.effectiveandroid.app.DialogDemo$1.handleMessage(DialogDemo.java:26)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.os.Handler.dispatchMessage(Handler.java:99)

 

7. Dialog.show()必須在主線程裡調用，但Dialog.dismiss()卻可以在任何線程中調用。

三種使用方式比較

1. 直接建立一個局部的Dialog對象

優點是變數是局部的容易理解和維護。缺點是Dialog對象難以控制，容易引發RuntimeException。

2. 把Dialog對象變成Activity的域

優點是Dialog對象可以重複利用，且Activity可以控制以保證Dialog不會在Activity生命週期外顯示。是推薦的使用方式。

3. 用Activity的方法onCreateDialog(), showDialog()和dismissDialog()

優點是Frameworks會幫忙照看Dialog，在大多數情況下這是推薦的做法。但是對於Activity提前死掉的情況，此方法必有RuntimeException，且無法迴避。

執行個體

 

public class DialogDemo extends Activity {    private static final int DISMISS_DIALOG = 1;        private ProgressDialog mBetterDialog;    private Handler mMainHandler = new Handler() {@Overridepublic void handleMessage(Message msg) {    switch (msg.what) {    case DISMISS_DIALOG:Dialog dialog = (Dialog) msg.obj;dialog.dismiss();break;    default:break;    }}    };    @Override    protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.dialog_demo);final Button sucking = (Button) findViewById(R.id.sucking);sucking.setOnClickListener(new View.OnClickListener() {    public void onClick(View v) {final Activity activity = DialogDemo.this;final ProgressDialog dialog = new ProgressDialog(activity);dialog.setTitle("Worst dialogging");dialog.setMessage("This is the worst dialogging scheme, NEVER use it. This dialog is easy to " +"run out of its attached activity, yielding WindowManager#BadTokenException if the activity is gone when dismissing");dialog.setIndeterminate(true);dialog.setCancelable(true);// You MUST do the show in main thread anywaydialog.show();new Thread(new Runnable() {    public void run() {SystemClock.sleep(10000);/* * IllegalArgumentException: View not attached to window manager * If the activity showing the dialog was killed before dismiss() out of rotation or locale changed, * the dialog will gone with activity, but when dismiss() yields "IllegalArgumentException: View not attached to  * window manager". * Checking isShowing() won‘t help. * Checking activity.isFinishing() won‘t help, either. * Dismiss it in main thread also won‘t give any help. */// THIS WON‘t WORK//if (dialog.isShowing()) {//    dialog.dismiss();//}//if (!activity.isFinishing()) {//    dialog.dismiss();//}Message msg = Message.obtain();msg.what = DISMISS_DIALOG;msg.obj = dialog;mMainHandler.sendMessage(msg);    }}).start();    }});final Button better = (Button) findViewById(R.id.better);better.setOnClickListener(new View.OnClickListener() {    public void onClick(View v) {mBetterDialog = new ProgressDialog(DialogDemo.this);mBetterDialog.setTitle("Better dialogging");mBetterDialog.setMessage("This dialogging can be used. The dialog object is a field of its activity, so activity can" +" control it to make sure dialog only lives within activity lifecircle");mBetterDialog.setIndeterminate(true);mBetterDialog.setCancelable(true);// You MUST do the show in main thread anywaymBetterDialog.show();new Thread(new Runnable() {    public void run() {SystemClock.sleep(10000);/* * This is much better, mBetterDialog is a field of its activity, so activity can take care of it in order * to make sure dialog only live within activity‘s life circle, to avoid any unexpected exceptions. */// THIS really works    if (mBetterDialog != null && mBetterDialog.isShowing()) {        mBetterDialog.dismiss();    }    }}).start();    }});final Button optional = (Button) findViewById(R.id.optional);optional.setOnClickListener(new View.OnClickListener() {    @SuppressWarnings("deprecation")    public void onClick(View v) {showDialog(0);new Thread(new Runnable() {    public void run() {SystemClock.sleep(10000);/* * This way works best for most of time, except if activity died before dismissing, exception must be * thrown: "IllegalArgumentException: View not attached to window manager". * Although activity takes care of its belonging dialog, there is no way to operate it manually any more. * First you do not have reference to dialog object and second, any manual operation only interferences * and breaks state maintained by frameworks. */dismissDialog(0);    }}).start();    }});    }    @Override    protected Dialog onCreateDialog(int id) {ProgressDialog d = new ProgressDialog(this);d.setTitle("Optional dialogging");d.setMessage("This dialogging scheme works best for most times, the dialogs are all taken care of by activitys and frameworks" +". Except for activity being killed during dialog showing");d.setIndeterminate(true);d.setCancelable(true);return d;    }    @Override    protected void onDestroy() {super.onDestroy();// Activity is dying, all its belonging dialogs should be dismissed, of course.if (mBetterDialog != null && mBetterDialog.isShowing()) {    mBetterDialog.dismiss();    mBetterDialog = null;}// For dialogs showed via showDialog(int), no way to stop it in onDestroy()//dismissDialog(0); // cause "IllegalArgumentException: no dialog with id 0 was ever shown via Activity#showDialog"    // This is because Activity has to manage its dialog during onPause() and onResume() to restore                  // dialogs‘ state. So if you manually dismiss it in onDestroy(), it will cause JE.//removeDialog(0);// cause "IllegalArgumentException: no dialog with id 0 was ever shown via Activity#showDialog", when// dismissing in thread.               // This is because Activity has to manage its dialog during onPause() and onResume() to restore                     // dialogs‘ state. So if you manually dismiss it in onDestroy(), it will cause JE.    }}

 

Android實戰技巧：Dialog （轉）