Question

I am trying to run this but It crashes when It gets to getDefaultSharedPreferences(). Why?

这里是优惠活动。当销毁时,发射<条码>Intentservice。

import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
import android.os.Bundle;
import android.preference.EditTextPreference;
import android.preference.PreferenceActivity;
import android.preference.PreferenceManager;

public class CCTDetectorActivity extends PreferenceActivity implements
        OnSharedPreferenceChangeListener {

    private SharedPreferences settings;
    static public String nameOfFile = "name_of_file";
    static public String nameOfFileDefaultValue = "detected_f.xml";
    static public String portNumber = "port_number";
    static public String portNumberDefaultValue = "25015";
    static public String keepAlive = "keep_alive";
    static public String keepAliveDefaultValue = "3";
    static public String nameOfSettings = "settings";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.layout.cct_detector_preferences_ui);
        settings = PreferenceManager.getDefaultSharedPreferences(this);
        settings.registerOnSharedPreferenceChangeListener(this);
        updateViews();
    }

    @Override
    protected void onDestroy() {
        Intent intent = new Intent(getBaseContext(), CCTDetectorService.class);
        startService(intent);
        super.onDestroy();
    }

    private void updateViews() {
        setSummeryfromPreferencesView(nameOfFile, nameOfFileDefaultValue);
        setSummeryfromPreferencesView(portNumber, portNumberDefaultValue);
        setSummeryfromPreferencesView(keepAlive, keepAliveDefaultValue);
    }

    private void setSummeryfromPreferencesView(String viewName, String DefValue) {
        String value = settings.getString(viewName, DefValue);
        EditTextPreference editTextView = (EditTextPreference) findPreference(viewName);
        editTextView.setText(value);
        editTextView.setSummary(value);
    }

    public void onSharedPreferenceChanged(SharedPreferences arg0, String arg1) {
        updateViews();
    }
}

Here is the IntentService that crashes. The line of the crash is marked with: "here it crashes!"

import android.app.IntentService;
import android.content.Intent;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;
import android.util.Log;

public class CCTDetectorService extends IntentService {

    private File serializedXmlFile;
    private DatagramSocket udpSocket;
    private boolean m_Listening = true;
    private ActiveCCTs activeCCTs = new ActiveCCTs();
    private SharedPreferences preferences;
    private Serializer serializer = new Persister();

    public CCTDetectorService() throws SocketException {
        super("CCTDetectorServiceThread");
        int port;
        String FILENAME;
        // here it crashes!
        preferences = PreferenceManager.getDefaultSharedPreferences(this);
        port = getIntFromSettingsEditText(CCTDetectorActivity.portNumber,
                CCTDetectorActivity.portNumberDefaultValue);
        activeCCTs.keepAlive = getIntFromSettingsEditText(
                CCTDetectorActivity.keepAlive,
                CCTDetectorActivity.keepAliveDefaultValue);
        FILENAME = preferences.getString(CCTDetectorActivity.nameOfFile,
                CCTDetectorActivity.nameOfFileDefaultValue);
        serializedXmlFile = new File(FILENAME);
        udpSocket = new DatagramSocket(port);
        udpSocket.setBroadcast(true);
    }
}

Answer 1

你在一个服务局的建筑中做了大量的工作。

http://www.un.org/Depts/DGACM/index_russian.htm Override #onCreate() and do You set up in which. 请打电话super.onCreate()。

Answer 2

In case of IntentService, it is better to do initialization in OnHandleIntent . Also In your Case the Context may not have been initialized. So move the code in constructor to OnHandleIntent

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