turn off airplane mode in Android

I would like to turn off the airplane mode if num>50, I implemented this code (from Toggle airplane mode in Android) but when executed I get a force close, can any one help here?

                if(num>50){
                    // read the airplane mode setting
                    boolean isEnabled = Settings.System.getInt(
                          getContentResolver(), 
                          Settings.System.AIRPLANE_MODE_ON, 0) == 1;

                    // toggle airplane mode
                    Settings.System.putInt(
                          getContentResolver(),
                          Settings.System.AIRPLANE_MODE_ON, isEnabled ? 0 : 1);

                    // Post an intent to reload
                    Intent intent = new Intent(Intent.ACTION_AIRPLANE_MODE_CHANGED);
                    intent.putExtra("state", !isEnabled);
                    sendBroadcast(intent);



                }

o.k. I implemented the premonitions but i would like to change the if statement:

if num>=50 and airplane mode=on toggle it off 
if  airplane mode=off and num<50 toggle it on

Can some one help me writing the new code? (I'm a newbie)

You most likely did not add WRITE_SETTING permissions to your AndroidManifest.xml:

<uses-permission android:name="android.permission.WRITE_SETTINGS" />

Also note that code:

 Intent intent = new Intent(Intent.ACTION_AIRPLANE_MODE_CHANGED);
 intent.putExtra("state", !isEnabled);
 sendBroadcast(intent);

Is not supposed to work, because according to documentation on ACTION_AIRPLANE_MODE_CHANGED:

This is a protected intent that can only be sent by the system.

And even though you can currently send this broadcast without System permissions, it may change in future releases of Android.