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  • Android实战技巧:Dialog

    from : http://blog.csdn.net/hitlion2008/article/details/7567549

    Dialog是任何系统都必须有的一个控件,作为辅助窗口,用于显示一些消息,或请求用户采取一引起操作等。

    在Android中也不例外,基本使用可能参看文档。
    使用时的注意事项

    1. BACK键能取消掉对话框(dismiss),但是却不会触发其onOkey和onCancel回调接口,所以如果你的对话框会改某些状态,一定要注意还有第三种方式取消对话框。

    2. 尽量少用模态对话框(Model dialog),如果Dialog.setCancellable(false),就变成了一个模态对话框,除了程序内部把其Dismiss,否则按什么键都无法将其取消。这是极差的用户体验,对话框本身就是一种干扰,再无法取消会把用户搞疯的。所以除非特别有必要,也即当执行某个操作时不希望被打破,才可以使用模态对话框。

    3. 尽量少用对话框,它对用户是一种干扰,除非需要用户做操作,或者做出选择。通常的一般性的通知用Toast或者Notification就足够了。

    4. 不要使用对话框风格的Activity,也即把Activity变成一个对话框。因为这样是自已定义的布局,与系统Dialog的风格可能会不一致。最严重的是当系统风格发生变化,Dialog的子类会变化,但Activity式的对话框就不会变化。可以在ICS中找一找Activity对话框,你会发现其OK是在左边,而ICS中系统Dialog的OK都是在右边的。

    5. 尽量保证Dialog对象活在Activity的生命周期之内,也即至多是在onCreate()和onDestroy()之间。

    6. 要想到和测试到Activity在其Dialog.dismiss()之前死掉的情况。因为Activity必须依附于某个正在显示的Activity实例,当显示和取消的时候其Activity实例必须存在,否则就会有"IllegalArgumentException: View not attached to window manager"。

    [plain] view plaincopyprint?
    05-15 02:45:26.320: E/AndroidRuntime(1161): java.lang.IllegalArgumentException: View not attached to window manager
    05-15 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()必须在主线程里调用,但Dialog.dismiss()却可以在任何线程中调用。
    三种使用方式比较

    1. 直接创建一个局部的Dialog对象

    优点是变量是局部的容易理解和维护。缺点是Dialog对象难以控制,容易引发RuntimeException。

    2. 把Dialog对象变成Activity的域

    优点是Dialog对象可以重复利用,且Activity可以控制以保证Dialog不会在Activity生命周期外显示。是推荐的使用方式。

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

    优点是Frameworks会帮忙照看Dialog,在大多数情况下这是推荐的做法。但是对于Activity提前死掉的情况,此方法必有RuntimeException,且无法回避。
    实例

    [java] view plaincopyprint?
    public class DialogDemo extends Activity {
    private static final int DISMISS_DIALOG = 1;

    private ProgressDialog mBetterDialog;

    private Handler mMainHandler = new Handler() {
    @Override
    public 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 anyway
    dialog.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 anyway
    mBetterDialog.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.
    }
    }

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  • 原文地址:https://www.cnblogs.com/wanqieddy/p/2574952.html
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