calling new intent from imageButton Created on listView

Question

I have a listView with an imageButton. When i click on the imageButton, I am trying to call a method in the main class that will display a toast message. However, when i click on the button, i get an error saying:

04-17 18:25:16.293: E/AndroidRuntime(9236): FATAL EXCEPTION: main
04-17 18:25:16.293: E/AndroidRuntime(9236): java.lang.NullPointerException
04-17 18:25:16.293: E/AndroidRuntime(9236):     at android.content.ContextWrapper.getResources(ContextWrapper.java:81)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at android.widget.Toast.<init>(Toast.java:94)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at android.widget.Toast.makeText(Toast.java:240)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at com.flamesavor.reme.ReMe.setAlarm(ReMe.java:69)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at com.flamesavor.reme.resources.ListViewAdapter.setAlarm(ListViewAdapter.java:62)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at com.flamesavor.reme.resources.ListViewAdapter$1.onClick(ListViewAdapter.java:49)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at android.view.View.performClick(View.java:4222)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at android.view.View$PerformClick.run(View.java:17343)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at android.os.Handler.handleCallback(Handler.java:615)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at android.os.Handler.dispatchMessage(Handler.java:92)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at android.os.Looper.loop(Looper.java:137)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at android.app.ActivityThread.main(ActivityThread.java:4895)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at java.lang.reflect.Method.invokeNative(Native Method)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at java.lang.reflect.Method.invoke(Method.java:511)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
04-17 18:25:16.293: E/AndroidRuntime(9236):     at dalvik.system.NativeStart.main(Native Method)

Below is my Arrayadapter where I have created the onClickListener. The listener calls a method in the adapter which then calls the setAlarm method in the Main Class (called 'ReMe').

public class ListViewAdapter extends android.widget.ArrayAdapter<String> {

    private Context context;
    private List<String> reminders;
    private View reminder;

    public ListViewAdapter(Context context, int resource, List<String> objects) {
        super(context, resource, objects);
        this.context = context;
        this.reminders = objects;
    }


    //Change textcolor to black. Everything else remains same
    @Override
    public View getView(int position, View convertView, ViewGroup parent){

        //Set view to convertView if the there are already rows created
        reminder = convertView;

        if(reminder == null){
            LayoutInflater inflator = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            reminder = inflator.inflate(R.layout.reminder_list_layout, parent, false);
        }

        //Set imageButton actionListener
        ImageButton alarmButton = (ImageButton) reminder.findViewById(R.id.reminder_alarmnavigation);
        alarmButton.setTag(reminder);
        alarmButton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {

                setAlarm((View) v.getTag());
            }
        });

        //Initialize and assign reminder title
        TextView reminder_title = (TextView) reminder.findViewById(R.id.reminder_title);
        reminder_title.setText(reminders.get(position));

        return reminder;
    }

    public void setAlarm(View view){
        ReMe reminder = new ReMe();
        reminder.setAlarm(view);

    }

}

Below is the method in the ReMe class:

public void setAlarm(View view){
    Intent intent = new Intent(this, SetReminder.class);
    TextView reminder_title  = (TextView) view.findViewById(R.id.reminder_title);

    Toast.makeText(ReMe.this, "testing", Toast.LENGTH_LONG).show();
    //intent.putExtra("com.flamesavor.reme.reminderTitle", reminder_title.getText());
    //startActivity(intent);
}

Not sure where I am making a mistake. Any help will be greatly appreciated.

Below is the modified code that tries to trigger an activity instead if creating a toast:

public void setAlarm(View view){
        Intent intent = new Intent(view.getContext(), SetReminder.class);
        TextView reminder_title  = (TextView) view.findViewById(R.id.reminder_title);       
        intent.putExtra("com.flamesavor.reme.reminderTitle", reminder_title.getText());
        startActivity(intent);
    }

Below is the error log that i get. Not sure why this is happening:

04-18 22:53:06.381: E/AndroidRuntime(8706): FATAL EXCEPTION: main
04-18 22:53:06.381: E/AndroidRuntime(8706): java.lang.NullPointerException
04-18 22:53:06.381: E/AndroidRuntime(8706):     at android.app.Activity.startActivityForResult(Activity.java:3423)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at android.app.Activity.startActivityForResult(Activity.java:3384)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at android.app.Activity.startActivity(Activity.java:3594)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at android.app.Activity.startActivity(Activity.java:3562)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at com.flamesavor.reme.ReMe.setAlarm(ReMe.java:67)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at com.flamesavor.reme.resources.ListViewAdapter.setAlarm(ListViewAdapter.java:62)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at com.flamesavor.reme.resources.ListViewAdapter$1.onClick(ListViewAdapter.java:49)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at android.view.View.performClick(View.java:4222)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at android.view.View$PerformClick.run(View.java:17343)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at android.os.Handler.handleCallback(Handler.java:615)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at android.os.Handler.dispatchMessage(Handler.java:92)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at android.os.Looper.loop(Looper.java:137)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at android.app.ActivityThread.main(ActivityThread.java:4895)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at java.lang.reflect.Method.invokeNative(Native Method)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at java.lang.reflect.Method.invoke(Method.java:511)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
04-18 22:53:06.381: E/AndroidRuntime(8706):     at dalvik.system.NativeStart.main(Native Method)

===================================================================================== Resolution (Edited): Set the FLAG_ACTIVITY_NEW_TASK and called the new activity in the context of the view.

TextView reminder_title  = (TextView) view.findViewById(R.id.reminder_title);   
        Intent intent = new Intent(view.getContext(), com.flamesavor.reme.SetReminder.class);
        intent.putExtra("com.flamesavor.reme.reminderTitle", reminder_title.getText());
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        view.getContext().startActivity(intent);

Answer 1

java.lang.NullPointerException 04-17 18:25:16.293: E/AndroidRuntime(9236): at android.content.ContextWrapper.getResources(ContextWrapper.java:81) 04-17 18:25:16.293: E/AndroidRuntime(9236): at android.widget.Toast.(Toast.java:94)

ReMe.java is not a Activity class. ReMe.this does not refer to a valid context.

So change to

Toast.makeText(view.getContext(), "testing", Toast.LENGTH_LONG).show();

http://developer.android.com/reference/android/view/View.html#getContext()

public final Context getContext ()

Added in API level 1
Returns the context the view is running in, through which it can access the current theme, resources, etc.

Returns
The view's Context.

Also change this

Intent intent = new Intent(this, SetReminder.class);

to

Intent intent = new Intent(view.getContext(), SetReminder.class);

Answer 2

You use "this" as the first parameter of the Intent constructor, which indicate that the current class is your context, so use the same "this" as the first parameter of Toast.makeText

Answer 3

If ReMe class does not belongs to context then there is a problem, because you must have to specify context or Activity to show Toast in the app