Question

我需要从外部Thread更新我的用户界面。我不能使用runOnUiThread，因为它是使用StandOut库的应用程序。

所以我在包含更新UI的方法的类中创建了我的Handler：

private final class UIHandler extends Handler {
    public static final int DISPLAY_UI_TOAST = 0;
    private static final int LOAD_PROFILE = 1;

    public UIHandler(Looper looper) {
        super(looper);
    }

    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
        case UIHandler.DISPLAY_UI_TOAST: {
            Context context = mw.getApplicationContext();
            Toast t = Toast.makeText(context, (String) msg.obj,
                    Toast.LENGTH_SHORT);
            t.show();
        }
        case UIHandler.LOAD_PROFILE:{
            loadProfile((String) msg.obj);
        }
        default:
            break;
        }
    }
}

然后我创建了一种向Handler

发送消息的方法

public void loadP(String prof){
    Message msg = uiHandler.obtainMessage(UIHandler.LOAD_PROFILE);
    msg.obj = prof;
    uiHandler.sendMessage(msg);
}

但是当我调用loadP（myProfile）时，应用程序崩溃时出现此错误：

08-25 19:55:08.428: E/AndroidRuntime(8602): FATAL EXCEPTION: UIHandler
08-25 19:55:08.428: E/AndroidRuntime(8602): android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4607)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:835)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.view.View.requestLayout(View.java:15129)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.view.View.requestLayout(View.java:15129)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.view.View.requestLayout(View.java:15129)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.view.ViewGroup.addView(ViewGroup.java:3249)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.view.ViewGroup.addView(ViewGroup.java:3196)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.view.ViewGroup.addView(ViewGroup.java:3172)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at com.vektor.amapper.elements.KeyElement.createButton(KeyElement.java:261)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at com.vektor.amapper.elements.KeyElement.setButton(KeyElement.java:159)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at com.vektor.amapper.elements.KeyElement.<init>(KeyElement.java:81)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at com.vektor.amapper.util.KeyElementManager.add(KeyElementManager.java:32)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at com.vektor.amapper.util.KeyElementManager.loadProfileUI(KeyElementManager.java:91)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at com.vektor.amapper.util.MapperController.loadProfileUI(MapperController.java:106)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at com.vektor.amapper.windows.ui.ProfilesPanel.loadProfile(ProfilesPanel.java:423)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at com.vektor.amapper.windows.ui.ProfilesPanel.access$1(ProfilesPanel.java:414)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at com.vektor.amapper.windows.ui.ProfilesPanel$UIHandler.handleMessage(ProfilesPanel.java:464)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.os.Looper.loop(Looper.java:137)
08-25 19:55:08.428: E/AndroidRuntime(8602):     at android.os.HandlerThread.run(HandlerThread.java:60)

我想补充说DISPLAY_UI_TOAST消息正在运行。

Answer 1

如果您只想处理某些消息，则无需扩展所有Handler类，只需实施Handler.Callback：

private final class UICallback implements Handler.Callback{
    public static final int DISPLAY_UI_TOAST = 0;
    private static final int LOAD_PROFILE = 1;

    @Override
    public boolean handleMessage(Message msg) {
        switch (msg.what) {
            case UICallback.DISPLAY_UI_TOAST: {
                Context context = mw.getApplicationContext();
                Toast t = Toast.makeText(context, (String) msg.obj,
                        Toast.LENGTH_SHORT);
                t.show();
                return true;
            }
            case UICallback.LOAD_PROFILE:{
                loadProfile((String) msg.obj);
                return true;
            }
            default:
                return false;
        }
    }
}

注意，在上面的代码中，处理消息时返回true，当消息不适合我们时返回false。

现在，使用主循环创建一个处理程序（以便在UI线程上运行所有消息），以及我们创建的回调：

Handler handler = new Handler(Looper.getMainLooper(),new UICallback());

Answer 2

请参阅以下链接，您可以获得一些想法......

Android: got CalledFromWrongThreadException in onPostExecute() - How could it be?

Android CalledFromWrongThreadException

Can't resolve CalledFromWrongThreadException with Handler

CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch views

Handler changing UI causes CalledFromWrongThreadException

通过Handler更新UI

2 个答案: