Button backButton;
Button customButton1;
private TextView mTextMessage;
private static final String TAG = "CardioActivity";

ExerciseDatabaseHelper mDatabaseHelper;

ArrayList<String> selectedItems = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_cardio);
    mDatabaseHelper = new ExerciseDatabaseHelper(this);

    ListView checked = (ListView) findViewById(R.id.checkable_list);
    checked.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);


    final ArrayList<String> items = new ArrayList<String>();
    items.add("Walking (40 Minutes)");
    items.add("Cycling (40 Minutes)");
    items.add("Step Aerobics (40 Minutes)");
    items.add("Elliptical Machine (50 Minutes)");
    items.add("Kayaking (1 Hour)");
    items.add("Tai Chi (1 Hour)");
    items.add("Yoga (50 Minutes)");
    items.add("Pilates (50 Minutes)");
    items.add("Ballroom Dancing (50 minutes)");


    final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.activity_cardio_list, R.id.text_workout,items);
    customButton1 = (Button) findViewById(R.id.customButton1);
    customButton1.setOnClickListener(new View.OnClickListener()
    {
        public void onClick(View v) {
            final EditText exerciseEditText = new EditText(CardioActivity.this);
            AlertDialog.Builder builder = new AlertDialog.Builder(CardioActivity.this);
            builder.setTitle("Customize Your Workout!");
            builder.setMessage("Enter your own custom workout!");
            builder.setView(exerciseEditText);
            DialogInterface.OnClickListener dialogClickListener = new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    switch(which){
                        case DialogInterface.BUTTON_POSITIVE:
                            // User clicked the Add button
                            String addedItem = (exerciseEditText.getText().toString());
                            items.add(addedItem);
                            adapter.notifyDataSetChanged();

                            break;

                        case DialogInterface.BUTTON_NEGATIVE:
                            // User clicked the Cancel button
                            break;
                    }
                }
            };

            // Set the alert dialog add button click listener
            builder.setPositiveButton("Add", dialogClickListener);

            // Set the alert dialog cancel button click listener
            builder.setNegativeButton("Cancel",dialogClickListener);

            AlertDialog dialog = builder.create();
            builder.setView(v);
            dialog.show();
        }
    });



    checked.setAdapter(adapter);
    checked.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id)
        {
            String selectedItem = ((TextView)view).getText().toString();

            if(selectedItems.contains(selectedItem))
            {
                selectedItems.remove(selectedItem);
            }
            else
            {
                selectedItems.add(selectedItem);
                AddData(selectedItem);

            }
        }
    });