事件的警报对话框错误

Question

编辑:向我所做的代码添加了一个额外的错误和修改。

我对java/android很陌生。当在我的AlertDialog类中触发一个事件时，我试图在SmartApp类中创建一个DataRobot。我在做这件事时遇到了一个错误。该事件正在SmartApp中触发并成功调用该函数，但当它到达AlertDialog alert = new AlertDialog.Builder(this).create();时，下面的错误将打印到logcat中。有没有人知道我做错了什么，或者有更好的方法来实现我想要的？

Logcat error:
02-05 22:39:27.081: VERBOSE/SmartApp(281): data alert event caught
02-05 22:39:27.081: VERBOSE/SmartApp(281): inside sendalert
02-05 22:39:27.090: WARN/System.err(281): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
02-05 22:39:27.122: WARN/System.err(281):     at android.os.Handler.<init>(Handler.java:121)
02-05 22:39:27.122: WARN/System.err(281):     at android.app.Dialog.<init>(Dialog.java:101)
02-05 22:39:27.141: WARN/System.err(281):     at android.app.AlertDialog.<init>(AlertDialog.java:63)
02-05 22:39:27.141: WARN/System.err(281):     at android.app.AlertDialog.<init>(AlertDialog.java:59)
02-05 22:39:27.161: WARN/System.err(281):     at android.app.AlertDialog$Builder.create(AlertDialog.java:786)
02-05 22:39:27.161: WARN/System.err(281):     at cpe495.smartapp.SmartApp.sendAlert(SmartApp.java:169)
02-05 22:39:27.171: WARN/System.err(281):     at cpe495.smartapp.SmartApp$3.dataAlertReceived(SmartApp.java:59)
02-05 22:39:27.201: WARN/System.err(281):     at cpe495.smartapp.DataRobot.fireDataAlertEvent(DataRobot.java:96)
02-05 22:39:27.201: WARN/System.err(281):     at cpe495.smartapp.DataRobot.analyzeData(DataRobot.java:32)
02-05 22:39:27.211: WARN/System.err(281):     at cpe495.smartapp.SmartApp$1.dataReceivedReceived(SmartApp.java:45)
02-05 22:39:27.222: WARN/System.err(281):     at cpe495.smartapp.ConnectDevice.fireDataReceivedEvent(ConnectDevice.java:71)
02-05 22:39:27.222: WARN/System.err(281):     at cpe495.smartapp.ConnectDevice.run(ConnectDevice.java:42)
02-05 22:39:27.242: WARN/System.err(281):     at java.lang.Thread.run(Thread.java:1096)   

//my smartapp class main ui
public class SmartApp extends Activity implements OnSharedPreferenceChangeListener {
    TextView smartConnectionStatus;
    TextView testOutputView;
    Thread cThread;
    private ConnectDevice cD = new ConnectDevice();
    private DataRobot dR = new DataRobot();
    private DataBuilder dB = new DataBuilder();
    private DataSender dS = new DataSender();


    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.intro);



        cD.addDataReceivedListener(new DataReceivedListener() {
            @Override
            public void dataReceivedReceived(DataReceivedEvent event) {
                // TODO Auto-generated method stub
                dR.analyzeData(event.getData());
            }
        });
        dR.addDataAlertListener(new DataAlertListener() {
            @Override
            public void dataAlertReceived(DataAlertEvent event) {
                Log.v("SmartApp", "data alert event caught");
                sendAlert();
            }
        });
    }
    /* Function for sending alerts that the user has exceeded a stress index */
    public void sendAlert() {
        Log.v("SmartApp", "inside sendalert");
        AlertDialog alert = new AlertDialog.Builder(this).create();
        Log.v("SmartApp", "after builder1");
        //Vibrator vibrator;
        //vibrator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
        //vibrator.vibrate(500);
        alert.setMessage("Testing alert dialog...");
        alert.setCancelable(false);
        alert.setButton("Ok", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                // TODO Auto-generated method stub
                dialog.cancel();
            }
        });
        Log.v("SmartApp", "after builder2");
        //AlertDialog alert = builder.create();
        alert.setTitle("Title");
        Log.v("SmartApp", "after builder3");
        alert.show();
        Log.v("SmartApp", "after builder4");
    }

}   

// datarobot class
public class DataRobot extends Activity {
/* This class is for analyzing the data */
private List _listeners = new ArrayList();
private List<DataAlertListener> _listeners2 = new ArrayList<DataAlertListener>();
private SmartDataObject data;
private int sI1;
private int sI2;
private float w1;
private float w2;
private float w3;
private int hRB;
private int hRVMin;
private int hRVMax;

public boolean analyzeData(SmartDataObject temp) {
    /* Analyze the data
     * Returns true if data was successfully analyzed
     * Returns false if an error occurred
     */
    data = temp;
    if(data.getHeartRate()>290) {
        fireDataAlertEvent();
    }
    fireDataAnalyzedEvent(data);
    return true; //for now this will always return true
}

public synchronized void addDataAnalyzedListener(DataAnalyzedListener listener) {
    _listeners.add(listener);
}
public synchronized void removeDataAnalyzedListener(DataAnalyzedListener listener) {
    _listeners.remove(listener);
}
private synchronized void fireDataAnalyzedEvent(SmartDataObject temp) {
    DataAnalyzedEvent dRE = new DataAnalyzedEvent(this, temp);
    Iterator listeners = _listeners.iterator();
    while(listeners.hasNext()) {
        ((DataAnalyzedListener)listeners.next()).dataAnalyzedReceived(dRE);
    }
}
public interface DataAnalyzedListener {
    public void dataAnalyzedReceived(DataAnalyzedEvent event);
}



public synchronized void addDataAlertListener(DataAlertListener listener) {
    _listeners2.add(listener);
}
public synchronized void removeDataAlertListener(DataAlertListener listener) {
    _listeners2.remove(listener);
}
private synchronized void fireDataAlertEvent() {
    DataAlertEvent dAE = new DataAlertEvent(this);
    Iterator listeners = _listeners2.iterator();
    while(listeners.hasNext()) {
        ((DataAlertListener)listeners.next()).dataAlertReceived(dAE);
    }
}
public interface DataAlertListener {
    public void dataAlertReceived(DataAlertEvent event);
}
}  

public class DataAlertEvent extends EventObject {
    public DataAlertEvent(Object source) {
        super(source);
        // TODO Auto-generated constructor stub
    }
}   

下面的是在试图修复之后添加的代码

02-06 10:27:30.673: VERBOSE/SmartApp(276): data alert event caught
02-06 10:27:31.013: WARN/System.err(276): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
02-06 10:27:31.042: WARN/System.err(276):     at android.os.Handler.<init>(Handler.java:121)
02-06 10:27:31.052: WARN/System.err(276):     at android.view.ViewRoot.<init>(ViewRoot.java:231)
02-06 10:27:31.052: WARN/System.err(276):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)
02-06 10:27:31.062: WARN/System.err(276):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
02-06 10:27:31.082: WARN/System.err(276):     at android.view.Window$LocalWindowManager.addView(Window.java:424)
02-06 10:27:31.082: WARN/System.err(276):     at android.app.Dialog.show(Dialog.java:241)
02-06 10:27:31.102: WARN/System.err(276):     at cpe495.smartapp.SmartApp$4.dataAlertReceived(SmartApp.java:80)
02-06 10:27:31.102: WARN/System.err(276):     at cpe495.smartapp.DataRobot.fireDataAlertEvent(DataRobot.java:96)
02-06 10:27:31.122: WARN/System.err(276):     at cpe495.smartapp.DataRobot.analyzeData(DataRobot.java:32)
02-06 10:27:31.122: WARN/System.err(276):     at cpe495.smartapp.SmartApp$2.dataReceivedReceived(SmartApp.java:66)
02-06 10:27:31.133: WARN/System.err(276):     at cpe495.smartapp.ConnectDevice.fireDataReceivedEvent(ConnectDevice.java:71)
02-06 10:27:31.133: WARN/System.err(276):     at cpe495.smartapp.ConnectDevice.run(ConnectDevice.java:42)
02-06 10:27:31.153: WARN/System.err(276):     at java.lang.Thread.run(Thread.java:1096)   

public class SmartApp extends Activity implements OnSharedPreferenceChangeListener {
    TextView smartConnectionStatus;
    TextView testOutputView;
    Thread cThread;
    private ConnectDevice cD = new ConnectDevice();
    private DataRobot dR = new DataRobot();
    private DataBuilder dB = new DataBuilder();
    private DataSender dS = new DataSender();


    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.intro);

    final AlertDialog alert = new AlertDialog.Builder(this).create();
    Log.v("SmartApp", "inside sendalert");
    //AlertDialog alert = new AlertDialog.Builder(this).create();
    Log.v("SmartApp", "after builder1");
    //Vibrator vibrator;
    //vibrator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
    //vibrator.vibrate(500);
    alert.setMessage("Testing alert dialog...");
    alert.setCancelable(false);
    alert.setButton("Ok", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            // TODO Auto-generated method stub
            dialog.cancel();
        }
    });
    Log.v("SmartApp", "after builder2");
    //AlertDialog alert = builder.create();
    alert.setTitle("Title");

        cD.addDataReceivedListener(new DataReceivedListener() {
            @Override
            public void dataReceivedReceived(DataReceivedEvent event) {
                // TODO Auto-generated method stub
                dR.analyzeData(event.getData());
            }
        });
        dR.addDataAlertListener(new DataAlertListener() {
            @Override
            public void dataAlertReceived(DataAlertEvent event) {
                Log.v("SmartApp", "data alert event caught");
                sendAlert();
                            alert.show();
            }
        });
    }

}   

Answer 1

必须在UI线程中创建和显示警报对话框，或者：

1. 在UI线程中创建一个处理程序。

处理程序mHandler =新的线程mHandler

类A实现Runnable { public void (){ // create并在这里显示警报}}

• ，当事件被触发时，调用：

A=新A()；mHandler.post(a);

Answer 2

AlertDialog.Builder(this).create()；应该从UI Thread.Try调用，将create()方法移动到Thread.Try。

Answer 3

这就是我得到的同样的错误，谢谢你建议把它放在UI线程上。不过，我在Xamarin工作，解决方案实际上是把它放在主线程上，如下所示：

        Xamarin.Forms.Device.BeginInvokeOnMainThread(() =>
        {
            page.DisplayAlert("Alert", message, null, "Cancel");
        });