Question

我正在编写一个应用程序，其中一个活动是：按下按钮后，它会向数据库中保存的联系人发送电子邮件和短信。我在我的短信部分遇到了一些麻烦，因为应用程序一直在用空指针崩溃，我不知道我哪里出错...任何帮助都值得赞赏：按下按钮时调用的方法：

public void onFinish() {
                final String[] personalInfo = db.getPersonalDetails();
                final Cursor contacts = db.getContacts();

                if (match == false) {
                    sendSms();

                    if (db.hasGmail()) {
                        Thread s = new Thread(new Runnable() {

                            public void run() {
                                String args[] = db.getGmail();
                                GmailSender sender = new GmailSender(args[0],
                                        args[1]);

                                Cursor c = db.getEmailContacts();
                                while (c.moveToNext()) {
                                    try {

                                        Log.e(args[0], args[1]);
                                        sender.sendMail(
                                                args[0],
                                                c.getString(c
                                                        .getColumnIndex("emailAddress")));
                                    } catch (Exception e) {
                                        Log.e("SendMail", e.getMessage(), e);
                                    }
                                }
                            }

                        });
                        s.start();
private void sendSms() {
        sms = new Intent(this, SMS.class);
        //sms.putExtra("message", message);
        this.startService(sms);
    }

SMS class:

public class SMS extends Service {
    Context context;
    SharedPreferences prefs = PreferenceManager
            .getDefaultSharedPreferences(context);;
    String BankAccount, BankNameAddress, SortCode;
    String message;

    @Override
    public IBinder onBind(Intent arg0) {
        return null;
    }

    public void initilizePrefs() {

        BankAccount = prefs.getString("BankAccount", null);
        BankNameAddress = prefs.getString("BankNameAddress", null);
        SortCode = prefs.getString("SortCode", null);

    }

    @Override
    public void onStart(Intent intent, int startid) {
        super.onStart(intent, startid);
        initilizePrefs();
        Bundle getvars = intent.getExtras();
        if (getvars != null) {
            message = getvars.getString("message");
        }
        char[] array = message.toCharArray();
        message = message.replaceAll(" ", "");

        String mes = "my account info is: " + BankNameAddress + " "
                + " account number: " + BankAccount + " Sort Code is: "
                + SortCode + " " + "Thank you so much!!";
        Log.e("message", message);
        try {
            // if (BankNameAddress != null && BankAccount != null && SortCode !=
            // null) {
            sendSMS("Help!! I've completely run out of money and need you to send some via bank transfer please. "
                    + mes);
        }

        /*
         * } else Toast.makeText( getBaseContext(),
         * "Please ensure all sections of preferences are filled",
         * Toast.LENGTH_SHORT).show();}
         */

        catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    private void sendSMS(String message) {
        Database db = new Database(this);

        Cursor cursor = db.getNumbers();
        db.onStop();
        Log.e("message", message);
        if (cursor != null) {
            while (cursor.moveToNext()) {
                String phoneNumber = cursor.getString(cursor
                        .getColumnIndex("number"));
                Log.e("number", phoneNumber);
                SmsManager sms = SmsManager.getDefault();
                sms.sendTextMessage(phoneNumber, null, message, null, null);
            }
        }
    }

}

logcat的：

03-08 15:32:25.784: E/AndroidRuntime(25227): FATAL EXCEPTION: main
03-08 15:32:25.784: E/AndroidRuntime(25227): java.lang.RuntimeException: Unable to instantiate service com.attack.android.SMS: java.lang.NullPointerException
03-08 15:32:25.784: E/AndroidRuntime(25227):    at android.app.ActivityThread.handleCreateService(ActivityThread.java:2380)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at android.app.ActivityThread.access$1700(ActivityThread.java:134)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1306)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at android.os.Handler.dispatchMessage(Handler.java:99)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at android.os.Looper.loop(Looper.java:137)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at android.app.ActivityThread.main(ActivityThread.java:4867)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at java.lang.reflect.Method.invokeNative(Native Method)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at java.lang.reflect.Method.invoke(Method.java:511)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1007)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:774)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at dalvik.system.NativeStart.main(Native Method)
03-08 15:32:25.784: E/AndroidRuntime(25227): Caused by: java.lang.NullPointerException
03-08 15:32:25.784: E/AndroidRuntime(25227):    at android.preference.PreferenceManager.getDefaultSharedPreferencesName(PreferenceManager.java:371)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at android.preference.PreferenceManager.getDefaultSharedPreferences(PreferenceManager.java:366)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at com.attack.android.SMS.<init>(SMS.java:25)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at java.lang.Class.newInstanceImpl(Native Method)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at java.lang.Class.newInstance(Class.java:1319)
03-08 15:32:25.784: E/AndroidRuntime(25227):    at android.app.ActivityThread.handleCreateService(ActivityThread.java:2377)
03-08 15:32:25.784: E/AndroidRuntime(25227):    ... 10 more

Answer 1

在将i传递给context之前，您忘记初始化getDefaultSharedPreferences。这样做：

  context=SMS.this;
  SharedPreferences prefs = PreferenceManager
                                       .getDefaultSharedPreferences(context);

还在方法内而不是在类级别初始化prefs。将initilizePrefs方法更改为：

Context context;
SharedPreferences prefs;
public void initilizePrefs() {
    context=SMS.this;
   prefs = PreferenceManager
        .getDefaultSharedPreferences(context);

 //your code here....

}

Answer 2

在SharedPreferences中使用它之前初始化context。

context = getApplicationContext();

将此行移至onStart（）

prefs = context.getSharedPreferences("NameOfSharedPreferences", <Mode>);

注意：在存储数据时，SharedPreferences的名称应与SharedPreferences的名称匹配。

在旁注中，最好在不同的java文件中编写Service。

短信活动协助

2 个答案: