java.lang.NullPointerException: Attempt to invoke virtual method 'void java.util.Calendar.setTimeInMillis(long)' on a null object reference

Question

I am new to Android and I'm currently working on a alarm clock app. But when i run it, i get a NullPointerException. Can anyone help me with that? Here is my code:

public class MainActivity extends ActionBarActivity {
    private Calendar c;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final TextView textView=(TextView)findViewById(R.id.textview1);
        final Button setbtn=(Button)findViewById(R.id.setclock);
        final Button unsetbtn=(Button)findViewById(R.id.unsetclock);
        setbtn.setOnClickListener(new OnClickListener(){
            @Override
            public void onClick(View v){
                long current=System.currentTimeMillis();
                c.setTimeInMillis(current);
                int mHour=c.get(Calendar.HOUR_OF_DAY);
                int mMinute=c.get(Calendar.MINUTE);
                new TimePickerDialog(MainActivity.this, new TimePickerDialog.OnTimeSetListener() {

                    @Override
                    public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
                        c.setTimeInMillis(System.currentTimeMillis());
                        c.set(Calendar.HOUR_OF_DAY,hourOfDay);
                        c.set(Calendar.MINUTE, minute);
                        c.set(Calendar.SECOND,0);
                        c.set(Calendar.MILLISECOND,0);
                        Intent intent=new Intent(MainActivity.this, CallAlarm.class);
                        PendingIntent sender= PendingIntent.getBroadcast(MainActivity.this,
                                1, intent, PendingIntent.FLAG_UPDATE_CURRENT);
                        AlarmManager am=(AlarmManager)getSystemService(ALARM_SERVICE);
                        am.set(AlarmManager.RTC_WAKEUP,c.getTimeInMillis(),sender);
                        String tmpS= format(hourOfDay)+""+format(minute);
                        textView.setText(tmpS);
                        Toast.makeText(MainActivity.this, "The alarm seted: "+tmpS,
                                Toast.LENGTH_LONG).show();
                    }
                },mHour,mMinute,true).show();
                }
        });
            unsetbtn.setOnClickListener(new OnClickListener(){
                public void onClick(View v){
                    Intent intent= new Intent(MainActivity.this, CallAlarm.class);
                    PendingIntent sender=PendingIntent.getBroadcast(MainActivity.this,0, intent, 0);
                    AlarmManager am=(AlarmManager)getSystemService(ALARM_SERVICE);
                    am.cancel(sender);
                    textView.setText("Current No Alarm!");
                    Toast.makeText(MainActivity.this, "Alarm Canceled", Toast.LENGTH_LONG).show();
                }
            });

        }
    private String format(int x)
    {
        String s=""+x;
        if(s.length()==1)
            s="0"+s;
        return s;
    }
}

And i get these in my logcat:

01-12 14:18:16.620: D/AndroidRuntime(2092): Shutting down VM
01-12 14:18:16.628: E/AndroidRuntime(2092): FATAL EXCEPTION: main
01-12 14:18:16.628: E/AndroidRuntime(2092): Process: com.example.alarm1, PID: 2092
**01-12 14:18:16.628: E/AndroidRuntime(2092): java.lang.NullPointerException: Attempt to invoke virtual method 'void java.util.Calendar.setTimeInMillis(long)' on a null object reference**
01-12 14:18:16.628: E/AndroidRuntime(2092):     at com.example.alarm1.MainActivity$1.onClick(MainActivity.java:32)
01-12 14:18:16.628: E/AndroidRuntime(2092):     at android.view.View.performClick(View.java:4756)
01-12 14:18:16.628: E/AndroidRuntime(2092):     at android.view.View$PerformClick.run(View.java:19749)
01-12 14:18:16.628: E/AndroidRuntime(2092):     at android.os.Handler.handleCallback(Handler.java:739)
01-12 14:18:16.628: E/AndroidRuntime(2092):     at android.os.Handler.dispatchMessage(Handler.java:95)
01-12 14:18:16.628: E/AndroidRuntime(2092):     at android.os.Looper.loop(Looper.java:135)
01-12 14:18:16.628: E/AndroidRuntime(2092):     at android.app.ActivityThread.main(ActivityThread.java:5221)
01-12 14:18:16.628: E/AndroidRuntime(2092):     at java.lang.reflect.Method.invoke(Native Method)
01-12 14:18:16.628: E/AndroidRuntime(2092):     at java.lang.reflect.Method.invoke(Method.java:372)
01-12 14:18:16.628: E/AndroidRuntime(2092):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
01-12 14:18:16.628: E/AndroidRuntime(2092):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

I have no idea why I get a null pointer exception. Can anyone help me with that?? Thank you so much !!!

What other debugging steps have you taken? Have you tried inspecting the calendar object that you're running the setTimeInMillis method on? — dethtron5000, Jan 12 '15 at 20:49
Please read [How to debug small programs](http://ericlippert.com/2014/03/05/how-to-debug-small-programs/). — honk, Jan 12 '15 at 20:54
possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — Simon, Jan 12 '15 at 21:56

score 11 · Answer 1 · answered Jan 12 '15 at 20:46

11

You're not initializing the calendar variable c. Try:

private Calendar c = Calendar.getInstance();

One word of advice: don't use one-character variable names, unless it's an iteration variable.

answered Jan 12 '15 at 20:46

Rudi Angela

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java.lang.NullPointerException: Attempt to invoke virtual method 'void java.util.Calendar.setTimeInMillis(long)' on a null object reference

1 Answers1