Java Android BroadcastReceiver：无法实例化接收器 - 没有空的构造函数
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Android BroadcastReceiver: Unable to instantiate receiver - no empty constructor
提问by Luca S.
I have a problem with a BroadcastReceiver. If I declare the action in the manifest in this way:
我有一个 BroadcastReceiver 的问题。如果我以这种方式在清单中声明操作：
<receiver android:name="com.app.activity.observer.DataEntryObserver" >
<intent-filter>
<action android:name= "@string/action_db_updated" />
</intent-filter>
</receiver>
where in the strings.xml I have:
在strings.xml中我有：
<string name="action_db_updated">com.app.DB_UPDATED</string>
everything works well. But if I change it to:
一切正常。但是如果我把它改成：
<receiver android:name="com.app.activity.observer.DataEntryObserver" >
<intent-filter>
<action android:name= "com.app.DB_UPDATED" />
</intent-filter>
</receiver>
I have this exception as the receiver is called:
我有这个例外，因为接收器被称为：
java.lang.RuntimeException: Unable to instantiate receiver com.app.activity.observer.DataEntryObserver: java.lang.InstantiationException: can't instantiate class com.app.activity.observer.DataEntryObserver; no empty constructor
java.lang.RuntimeException：无法实例化接收器 com.app.activity.observer.DataEntryObserver：java.lang.InstantiationException：无法实例化类 com.app.activity.observer.DataEntryObserver；没有空的构造函数
I would keep the working version but the Play store doesn't allow me to publish the app because it expects a string value and not a variable @string/..
我会保留工作版本，但 Play 商店不允许我发布应用程序，因为它需要一个字符串值而不是变量 @string/..
my receiver is an outerclass and is defined as:
我的接收器是一个外部类，定义为：
public class DataEntryObserver extends BroadcastReceiver{
private AppUsageLoader dLoader;
public DataEntryObserver(AppUsageLoader dLoader) {
this.dLoader = dLoader;
IntentFilter filter = new IntentFilter(
ReaLifeApplication.ACTION_DB_UPDATED);
dLoader.getContext().registerReceiver(this, filter);
}
@Override
public void onReceive(Context arg0, Intent arg1) {
// Tell the loader about the change.
dLoader.onContentChanged();
}
}
}
采纳答案by 130nk3r5
Make the class a static class, otherwise it's "seen" as part of the original containing class instance.
使类成为静态类，否则它会被“视为”原始包含类实例的一部分。
thus:
因此：
public static class DataEntryObserver extends BroadcastReceiver{
public DeviceAdminSampleReceiver() {
super();
}
...
回答by ROXI
need to empty constructor
需要清空构造函数
public DataEntryObserver() {
this.dLoader = null;
}
回答by Roberto
You need an empty constructor like this:
你需要一个像这样的空构造函数：
public class DataEntryObserver extends BroadcastReceiver{
private AppUsageLoader dLoader;
// Empty constructor
public DataEntryObserver() { }
public DataEntryObserver(AppUsageLoader dLoader) {
this.dLoader = dLoader;
IntentFilter filter = new IntentFilter(
ReaLifeApplication.ACTION_DB_UPDATED);
dLoader.getContext().registerReceiver(this, filter);
}
@Override
public void onReceive(Context arg0, Intent arg1) {
// Tell the loader about the change.
dLoader.onContentChanged();
}
}
Although I'm not sure if keeping the non-empty constructor will generate the same error. If it does, you will have to remove it.
虽然我不确定保留非空构造函数是否会产生相同的错误。如果是这样，您将不得不将其删除。
