I am scheduling few functions by using timer handler.This is what happens.
When i press the button the timer starts sending sms and it opens another activity. Then in the another activity i have put the stop button to terminate the timer and return back to main activity. The timer terminates but it crashes the app and return back to main activity.
Here is the code
MainActivity.java
public class MainActivity extends FragmentActivity{
protected static final int CONTACT_PICKER_RESULT = 0;
int count=0;
private RadioButton radioBtnten;
private RadioButton radioBtnone;
Button sendBtn,contact;
EditText txtphoneNo;
EditText txtMessage;
GPSTracker gps;
Timer timer;
TimerTask timerTask;
final Handler handler = new Handler();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LocationManager service = (LocationManager) getSystemService(LOCATION_SERVICE);
boolean enabled = service.isProviderEnabled(LocationManager.GPS_PROVIDER);
if (!enabled)
{
Toast.makeText(getApplicationContext(), "Your GPS IS NOT ON SWITCH IT ON HERE",Toast.LENGTH_LONG).show();
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivity(intent);
}
radioBtnten=(RadioButton)findViewById(R.id.ten);
radioBtnone=(RadioButton)findViewById(R.id.one);
sendBtn = (Button) findViewById(R.id.btnSendSMS);
txtphoneNo= (EditText) findViewById(R.id.editTextPhoneNo);
contact = (Button)findViewById(R.id.contact);
//txtMessage //= (EditText) findViewById(R.id.editTextSMS);
gps = new GPSTracker(MainActivity.this);
contact.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent intent = new Intent(Intent.ACTION_PICK,ContactsContract.Contacts.CONTENT_URI);
intent.setType(ContactsContract.CommonDataKinds.Phone.CONTENT_TYPE);
startActivityForResult(intent, CONTACT_PICKER_RESULT);
}
});
sendBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
startTimer();
sendSMSMessage();
Intent toAnotherActivity = new Intent(MainActivity.this, maps.class);
startActivityForResult(toAnotherActivity, 0);
}
});
}
public void startTimer() {
//set a new Timer
timer = new Timer();
//initialize the TimerTask's job
initializeTimerTask();
//schedule the timer, after the first 5000ms the TimerTask will run every 10000ms//
if(radioBtnten.isChecked()==true)
timer.schedule(timerTask, 5000, 10000);
// if(radioBtn2.isSelected()==true)
else if(radioBtnone.isChecked()==true)
timer.schedule(timerTask, 5000, 1000);
}
public void initializeTimerTask() {
timerTask = new TimerTask() {
public void run() {
//use a handler to run a toast that shows the current timestamp
handler.post(new Runnable() {
public void run() {
//get the current timeStamp
Toast.makeText(getApplicationContext(), "your message has been sent, the message(s) sent are:-"+count++,Toast.LENGTH_LONG).show();
sendSMSMessage();
//show the toast
}
});
}
};
}
public void stoptimertask(View v)
{
//stop the timer, if it's not already null
Toast.makeText(getApplicationContext(), "Stop button pressed",Toast.LENGTH_LONG).show();
if (timer != null)
{
timer.cancel();
timer = null;
}
}
protected void sendSMSMessage() {
Log.i("Send SMS", "");
double latitude = gps.getLatitude();
double longitude = gps.getLongitude();
String phoneNo = txtphoneNo.getText().toString();
String message = "These are my co-ordinates:-"+ latitude + ", " + longitude;
try {
SmsManager smsManager = SmsManager.getDefault();
smsManager.sendTextMessage(phoneNo, null, message, null, null);
Toast.makeText(getApplicationContext(), "SMS sent.",
Toast.LENGTH_LONG).show();
} catch (Exception e) {
Toast.makeText(getApplicationContext(),
"SMS faild, please try again.",
Toast.LENGTH_LONG).show();
e.printStackTrace();
}
}
The next activity is this
maps.java
public class maps extends FragmentActivity implements LocationListener {
MainActivity maine= new MainActivity();
GoogleMap googleMap;
Button stop;
Timer timer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//show error dialog if GoolglePlayServices not available
if (!isGooglePlayServicesAvailable()) {
finish();
}
setContentView(R.layout.maps);
stop = (Button)findViewById(R.id.stop);
stop.setOnClickListener(new View.OnClickListener()
{
public void onClick(View aView)
{
maine.stoptimertask(aView);
Intent toAnotherActivity = new Intent(aView.getContext(), MainActivity.class);
startActivityForResult(toAnotherActivity, 0);
//stop the timer, if it's not already null
Toast.makeText(getApplicationContext(), "Stop button pressed",Toast.LENGTH_LONG).show();
}
});
i created an object of mainactivity and called the stoptimertask method. The app crashes with this log cat :-
FATAL EXCEPTION: main
Process: com.example.textmessage, PID: 27301
java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:105)
at com.example.textmessage.MainActivity.stoptimertask(MainActivity.java:129)
at com.example.textmessage.maps$1.onClick(maps.java:42)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
What i want is when the button stop is pressed in maps.java, the sending sms function should stop and it should return back to MainActivity.java
