我已经阅读了其他存在的线程，但是它们都无法解决我的问题。
我正在构建一个应用程序，该应用程序在没有互联网的情况下缓存消息并将其存储到数据库中。这个想法是，当有网络连接时，它会从数据库中提取数据并在后台发送消息-为此，我制作了一个广播接收器，并使其接收“ android.net.conn.CONNECTIVITY_CHANGE”广播-然后制作了该应用将消息发布到服务器
网络更改时出现的错误：
java.lang.RuntimeException: Unable to instantiate receiver com.tanvirsingh.fragmentsdemo.NetworkChangeReceiver: java.lang.InstantiationException: java.lang.Class<com.tanvirsingh.fragmentsdemo.NetworkChangeReceiver> has no zero argument constructor
广播接收器类（NetworkChangeReceiver.java）：
public class NetworkChangeReceiver extends BroadcastReceiver{
private static final String TAGNCR = "JSON";
private final Handler handler; // Handler used to execute code on the UI thread
public NetworkChangeReceiver(Handler handler) {
this.handler = handler;
}
DataBaseHelper myDB;
final String MESSAGES_ENDPOINT = "";
@Override
public void onReceive(Context context, Intent intent) {
int[] type = {ConnectivityManager.TYPE_MOBILE, ConnectivityManager.TYPE_WIFI};
if (isNetworkAvailable(context) == true){
//check for messages to be sent
myDB = new DataBaseHelper(context);
Cursor res = myDB.getAllData();
if (res.getCount() == 0)
{
Log.d(TAG,"No data found");
return;
}
StringBuffer buffer = new StringBuffer();
while( res.moveToNext()){
buffer.append("Params: " + res.getString(0)+ "\n");
}
Log.d(TAGNCR,buffer.toString());
return;
} else {
}
}
public void SendMessageFromDB(RequestParams param){
AsyncHttpClient client = new AsyncHttpClient();
//pusher
PusherOptions options = new PusherOptions();
options.setCluster("");
Pusher pusher = new Pusher("", options);
Channel channel = pusher.subscribe("my-channel");
channel.bind("my-event", new SubscriptionEventListener() {
@Override
public void onEvent(String channelName, String eventName, final String data) {
System.out.println(data);
}
});
pusher.connect();
final RequestParams params = param;
client.post(MESSAGES_ENDPOINT + "/messages", params, new JsonHttpResponseHandler() {
@Override
public void onSuccess(int statusCode, Header[] headers, JSONObject response) {
handler.post(new Runnable() {
@Override
public void run() {
Log.d(TAG, params.toString());
}
});
}
@Override
public void onFailure(int statusCode, Header[] headers, String responseString, Throwable throwable) {
//Toast.makeText(, "Something went wrong :(", Toast.LENGTH_LONG).show();
}
});
return;
}
//function to check if internet is available
private static boolean isNetworkAvailable(Context context){
try{
ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
if (activeNetwork != null) { // connected to the internet and not in Airplane mode
if (activeNetwork.getType() == ConnectivityManager.TYPE_WIFI) {
// connected to wifi
Toast.makeText(context, activeNetwork.getTypeName() + " Connected", Toast.LENGTH_SHORT).show();
return true;
} else if (activeNetwork.getType() == ConnectivityManager.TYPE_MOBILE) {
// connected to the mobile data
Toast.makeText(context, activeNetwork.getTypeName() + " Connected", Toast.LENGTH_SHORT).show();
return true;
}
} else {
// not connected to the internet
Toast.makeText(context, "No internet connection available!", Toast.LENGTH_SHORT).show();
}
} catch (Exception e){
return false;
}
return false;
}
}
根据要求进行堆栈跟踪：
04-05 16:36:29.828 3420-3420/com.tanvirsingh.fragmentsdemo E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.tanvirsingh.fragmentsdemo, PID: 3420
Theme: themes:{default=overlay:system, iconPack:com.baranovgroup.nstyle, fontPkg:com.baranovgroup.nstyle, com.android.systemui=overlay:com.baranovgroup.nstyle, com.android.systemui.navbar=overlay:system}
java.lang.RuntimeException: Unable to instantiate receiver com.tanvirsingh.fragmentsdemo.NetworkChangeReceiver: java.lang.InstantiationException: java.lang.Class<com.tanvirsingh.fragmentsdemo.NetworkChangeReceiver> has no zero argument constructor
at android.app.ActivityThread.handleReceiver(ActivityThread.java:2752)
at android.app.ActivityThread.-wrap14(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1440)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5471)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:102)
Caused by: java.lang.InstantiationException: java.lang.Class<com.tanvirsingh.fragmentsdemo.NetworkChangeReceiver> has no zero argument constructor
at java.lang.Class.newInstance(Native Method)
at android.app.ActivityThread.handleReceiver(ActivityThread.java:2747)
at android.app.ActivityThread.-wrap14(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1440)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5471)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:102)
Broadcast Receiver与Fragment许多其他类相同且与之相同的其他类应该具有不带参数的默认构造函数。
只需添加默认构造函数：
public NetworkChangeReceiver() {
}
之所以这样，是因为Android系统知道类及其包的名称，但对它的参数一无所知。它使用反射，像
Class c = Class.forName(className);
YourBroadcastReceiver broadcastReceiver = (YourBroadcastReceiver)c.newInstance();
没有默认构造函数，newInstance（）将生成错误。
UPD：
在您的情况下，应从SendMessageFromDBBroadcastReceiver中删除方法以分离类。
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