I am trying to have an alert appear on a certain time. I was able to do that, but when I press the snooze button it works, I get another alert but I also get some errors. Find the errors below:
11-19 12:50:26.755: E/AndroidRuntime(452): FATAL EXCEPTION: main
11-19 12:50:26.755: E/AndroidRuntime(452): java.lang.NullPointerException
11-19 12:50:26.755: E/AndroidRuntime(452): at android.app.PendingIntent.getActivity(PendingIntent.java:191)
11-19 12:50:26.755: E/AndroidRuntime(452): at com.example.servicealarmdemo2.MainActivity.repeat(MainActivity.java:124)
11-19 12:50:26.755: E/AndroidRuntime(452): at com.example.servicealarmdemo2.AlertDemo$2.onClick(AlertDemo.java:58)
11-19 12:50:26.755: E/AndroidRuntime(452): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:159)
11-19 12:50:26.755: E/AndroidRuntime(452): at android.os.Handler.dispatchMessage(Handler.java:99)
11-19 12:50:26.755: E/AndroidRuntime(452): at android.os.Looper.loop(Looper.java:123)
11-19 12:50:26.755: E/AndroidRuntime(452): at android.app.ActivityThread.main(ActivityThread.java:3683)
11-19 12:50:26.755: E/AndroidRuntime(452): at java.lang.reflect.Method.invokeNative(Native Method)
11-19 12:50:26.755: E/AndroidRuntime(452): at java.lang.reflect.Method.invoke(Method.java:507)
11-19 12:50:26.755: E/AndroidRuntime(452): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-19 12:50:26.755: E/AndroidRuntime(452): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-19 12:50:26.755: E/AndroidRuntime(452): at dalvik.system.NativeStart.main(Native Method)
the function that repeats the alert is in MainActivity.java
public void repeat() {
Intent i = new Intent("com.example.servicealarmdemo2.demoactivity");
PendingIntent operation = PendingIntent.getActivity(getBaseContext(), 0, i, Intent.FLAG_ACTIVITY_NEW_TASK);
AlarmManager alarmManager = (AlarmManager) getBaseContext().getSystemService(ALARM_SERVICE);
long time= System.currentTimeMillis();
EditText text=(EditText)findViewById(R.id.editText1);
String str = text.getText().toString();
long t=Long.parseLong(str);
alarmManager.set(AlarmManager.RTC_WAKEUP, time+( t*60*1000), operation);
}
and the following two classes are for the alerts:
AlertDemo.java
package com.example.servicealarmdemo2;
import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.ComponentName;
import android.content.Intent;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.Bundle;
import android.support.v4.app.DialogFragment;
import android.view.WindowManager.LayoutParams;
import android.widget.EditText;
public class AlertDemo extends DialogFragment {
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
/** Turn Screen On and Unlock the keypad when this alert dialog is displayed */
getActivity().getWindow().addFlags(LayoutParams.FLAG_TURN_SCREEN_ON | LayoutParams.FLAG_DISMISS_KEYGUARD);
/** Creating a alert dialog builder */
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
/** Setting title for the alert dialog */
builder.setTitle("Alarm");
/** Setting the content for the alert dialog */
builder.setMessage("An Alarm by AlarmManager");
/** Defining an OK button event listener */
builder.setPositiveButton("Take", new OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
/** Exit application on click OK */
getActivity().finish();
}
});
builder.setNegativeButton("Snooze", new OnClickListener() {
// @Override
public void onClick(DialogInterface dialog, int which) {
/** Exit application on click OK */
//getActivity().finish();
// repeat();
System.out.println("REPEAT");
new MainActivity().repeat();
//System.out.println("Activities: "+m);
}
});
/** Creating the alert dialog window */
return builder.create();
}
/** The application should be exit, if the user presses the back button */
@Override
public void onDestroy() {
super.onDestroy();
getActivity().finish();
}
// public void repeat() {
// MainActivity.repeat();
// }
// public void repeat() {
// Intent i = new Intent("com.example.servicealarmdemo2.demoactivity");
//// PendingIntent operation = PendingIntent.getActivity(getBaseContext(), 0, i, Intent.FLAG_ACTIVITY_NEW_TASK);
// PendingIntent operation = PendingIntent.getActivity(getActivity().getBaseContext(), 0, i, Intent.FLAG_ACTIVITY_NEW_TASK);
// AlarmManager alarmManager = (AlarmManager) getActivity().getBaseContext().getSystemService(getActivity().ALARM_SERVICE);
// long time= System.currentTimeMillis();
// EditText text=(EditText)getActivity().findViewById(R.id.editText1);
// String str = text.getText().toString();
// long t=Long.parseLong(str);
// alarmManager.set(AlarmManager.RTC_WAKEUP, time+( t*60*1000), operation);
//
// }
}
and DemoActivity.java
package com.example.servicealarmdemo2;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.WindowManager.LayoutParams;
import android.widget.Toast;
public class DemoActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/** Creating an Alert Dialog Window */
AlertDemo alert = new AlertDemo();
/** Opening the Alert Dialog Window */
alert.show(getSupportFragmentManager(), "AlertDemo");
}
}
new MainActivity().repeat();
Never instantiate activities using new
, only via Intent
.
Reason for NPE is that the code is trying to use the activity as a Context
but it has not been properly initialized for such use.
Technically, getBaseContext()
returns null
and getActivity()
unconditionally calls a method on the passed-in context.
The way you did code its not look good, and Null-pointer is because of wrong Context
.
PendingIntent operation = PendingIntent.getActivity(getBaseContext(), 0, i, Intent.FLAG_ACTIVITY_NEW_TASK);
Try to pass activity context while calling repeat()
function.
new MainActivity().repeat(Activity context); //pass here activity context.
public void repeat(Activity ctx) {
Intent i = new Intent("com.example.servicealarmdemo2.demoactivity");
PendingIntent operation = PendingIntent.getActivity(ctx, 0, i, Intent.FLAG_ACTIVITY_NEW_TASK);
.
.
.
.
}
But not a good way to achieve!
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