小编kmi*_*ark的帖子

我刚刚设置了一个onClick方法,该方法写在activity类中,只要单击该按钮就会被调用.即使在它进入方法之前,应用程序崩溃了.

单击浮动操作按钮时出现的错误消息;

java.lang.IllegalArgumentException: Expected receiver of type com.example.bob.vexteamqueuing.AdminControl,
but got android.support.v7.view.ContextThemeWrapper java.lang.IllegalArgumentException:
Expected receiver of type com.example.bob.vexteamqueuing.AdminControl, but got android.support.v7.view.ContextThemeWrapper

at java.lang.reflect.Method.invoke(Native Method)
at android.view.View$DeclaredOnClickListener.onClick(View.java:4447)
at android.view.View.performClick(View.java:5198)
at android.view.View$PerformClick.run(View.java:21147)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)   
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

活动的XML代码:

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/NoActionBar">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:popupTheme="@style/AppTheme.PopupOverlay"
        />

</android.support.design.widget.AppBarLayout>

<include layout="@layout/content_admin_control" />

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="@dimen/fab_margin"
    android:src="@android:drawable/ic_input_add"
    android:onClick="createNewTournament"
    android:clickable="true" />

AdminControl活动Java代码:

  public class AdminControl extends AppCompatActivity { …

有没有办法访问firebase数据而无需使用addValueEventListener？这样,我可以在需要时访问数据,而不是仅在数据发生变化时才限制访问数据.

我在Java编码.谢谢 :)

是否可以使 onDataChange() 不只在设置监听器时触发，而仅在实际数据发生变化时触发？

我正在尝试在Android应用程序中实现Firebase主题消息,我​​正在尝试构建一个HTTP post请求,并且我收到的响应代码为400.我已经查看了各种解决方案,但它们似乎都没有救命.

这是我调用AsyncTask的子类的地方:

try{new FirebaseSendMessage().execute("Hello world");}
                catch (Exception e) {
                    Log.d("Exception", e.toString());
                }

这是我的Async Task类的子类.

class FirebaseSendMessage  extends AsyncTask<String, Integer, Double> {
private final static String USER_AGENT = "Mozilla/5.0";
private final static String AUTH_KEY = "<My firebase authorization key obtained from firebase>";

private Exception exception;

protected Double doInBackground(String... params) {
    try {
        sendRequest(params);
    } catch (Exception e) {
        this.exception = e;
    }
    return null;
}

protected void onPostExecute(Long l) {
    // TODO: check this.exception
    // TODO: do something with the …