最后我在对话框中添加了一个键监听器来监听Back键。虽然没有覆盖onBackPressed()那么优雅，但它还是可以工作的。代码如下：

dlgDetails = new AlertDialog.Builder(this)
    .setOnKeyListener(new DialogInterface.OnKeyListener() {
        @Override
        public boolean onKey (DialogInterface dialog, int keyCode, KeyEvent event) {
            if (keyCode == KeyEvent.KEYCODE_BACK && 
                event.getAction() == KeyEvent.ACTION_UP && 
                !event.isCanceled()) {
                dialog.cancel();
                showDialog(DIALOG_MENU);
                return true;
            }
            return false;
        }
    })
    //(Rest of the .stuff ...)

答案在Kotlin看到这里：Not working onbackpressed when setcancelable of alertdialog is false

找到了一个更短的解决方案：）试试这个：

accountDialog = builder.create();

        accountDialog.setOnCancelListener(new OnCancelListener() {

            @Override
            public void onCancel(DialogInterface dialog) {
                dialog.dismiss();
                activity.finish();

            }
        });

这将处理“后退”按钮和在对话框外部单击：

yourBuilder.setOnCancelListener(new OnCancelListener() {
    @Override
    public void onCancel(DialogInterface dialog) {
        dialog.cancel();
        // do your stuff...
    }
});

dialog.cancel()是密钥：对于dialog.dismiss()，这将仅处理对话框外部的点击，如上所述。

我在java类中创建了一个新函数，并从对话框生成器的onClick方法调用了该函数。

public class Filename extends Activity(){

@Override
onCreate(){
 //your stuff
 //some button click launches Alertdialog
}

public void myCustomDialog(){
 AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);
 //other details for builder
      alertDialogBuilder.setNegativeButton("BACK",
            new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
                         dialod.dismiss;
                         myCustomBack();
                    }
      });

 AlertDialog alertDialog = alertDialogBuilder.create();
 alertDialog.setCanceledOnTouchOutside(true);
 alertDialog.show();
}

public void myCustomBack(){
  if(condition1){
    super.onBackPressed();
  }
  if(condition 2){
    //do  stuff here
  }
}

@Override
public void onBackPressed(){
  //handle case here
  if (condition A)
    //Do this
  else 
    //Do that
}

}

下面是一个基于answer from Pooks的C#实际解决方案：
首先，我们必须创建一个新类来处理事件：

private sealed class KeyListener : Java.Lang.Object, IDialogInterfaceOnKeyListener
{
    private readonly Action _action;

    public KeyListener(Action action)
    {
        _action = action;
    }

    public bool OnKey(IDialogInterface dialog, [GeneratedEnum] Android.Views.Keycode keyCode, KeyEvent e)
    {
        var isBack = keyCode == Android.Views.Keycode.Back
            && e.Action == KeyEventActions.Up
            && !e.IsCanceled;

        if (isBack)
            _action.Invoke();

        return isBack;
    }
}

我们需要一个动作来接收事件：

private void OnBackPressed()
{
    // ... do the stuff
}

现在，我们可以设置此事件：

var dlgDetails = new AlertDialog.Builder(this)
    .SetOnKeyListener(new KeyListener(OnBackPressed))
    // add further set ups
    .Create();