Geliştirdiğim uygulamada bir fragment tan diğer bir fragment a nesne aktarırken NullPointerException hatası alıyorum. Fragment lar ActionBar içinde navigasyon modunda bulunuyorlar. Nerede hata yaptığımı gösterebilirseniz sevinirim. Yazdığım kod:

package com.restaurantexample.fragment;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;

import com.restaurantexample.adapter.MenuItemAdapter;
import com.restaurantexample.listener.OnMenuItemPressListener;
import com.restaurantexample.main.R;
import com.restaurantexample.menuitems.BaseOfMenuItems;

public class DrinksFragment extends Fragment implements OnItemClickListener {

    private List<BaseOfMenuItems> drinks;
    private BaseOfMenuItems cocaCola, fanta, pepsi, mirinda, sevenUp, juice,
            water, lemonade, mohito;
    private ListView lv;
    private MenuItemAdapter adapter;
    private int layoutId;
    private int productId;
    private int volumeId;
    private int priceId;
    private int imgId;
    private OnMenuItemPressListener menuItemListener;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        View drinksView = inflater.inflate(R.layout.drinks_fragment, container,
                false);
        drinks = new ArrayList<BaseOfMenuItems>();
        cocaCola = new BaseOfMenuItems("Кока кола", "330 мл", 50,
                R.drawable.ic_launcher);
        drinks.add(cocaCola);
        fanta = new BaseOfMenuItems("Фанта", "330 мл", 50,
                R.drawable.ic_launcher);
        drinks.add(fanta);
        pepsi = new BaseOfMenuItems("Пепси", "330 мл", 50,
                R.drawable.ic_launcher);
        drinks.add(pepsi);
        mirinda = new BaseOfMenuItems("Миринда", "330 мл", 50,
                R.drawable.ic_launcher);
        drinks.add(mirinda);
        sevenUp = new BaseOfMenuItems("7 уп", "330 мл", 50,
                R.drawable.ic_launcher);
        drinks.add(sevenUp);
        juice = new BaseOfMenuItems("Сок", "250 мл", 150,
                R.drawable.ic_launcher);
        drinks.add(juice);
        water = new BaseOfMenuItems("Негазированная вода", "500 мл", 40,
                R.drawable.ic_launcher);
        drinks.add(water);
        lemonade = new BaseOfMenuItems("Домашний лимонад", "300 мл", 150,
                R.drawable.ic_launcher);
        drinks.add(lemonade);
        mohito = new BaseOfMenuItems("Мохито безалкогольный", "300 мл", 200,
                R.drawable.ic_launcher);
        drinks.add(mohito);

        layoutId = R.layout.drinks_list;
        productId = R.id.product;
        volumeId = R.id.volume;
        priceId = R.id.price;
        imgId = R.id.imgDrinks;

        lv = (ListView) drinksView.findViewById(R.id.drinkslistview);
        adapter = new MenuItemAdapter(getActivity(), drinks, layoutId,
                productId, volumeId, priceId, 0, imgId);
        lv.setAdapter(adapter);

        return drinksView;
    }

    @Override
    public void onAttach(Activity activity) {
        // TODO Auto-generated method stub
        super.onAttach(activity);
        //menuItemListener = (OnMenuItemPressListener) getActivity();
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onActivityCreated(savedInstanceState);

        lv.setOnItemClickListener(this);
    }

    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
        // TODO Auto-generated method stub

        menuItemListener.onMenuItemPressed(drinks.get(arg2));
    }
}

Nesneyi aktarmak istediğim fragment;

package com.restaurantexample.fragment;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;

import com.restaurantexample.adapter.MenuItemAdapter;
import com.restaurantexample.main.R;
import com.restaurantexample.menuitems.BaseOfMenuItems;

public class BasketFragment extends Fragment {

    private List<BaseOfMenuItems> menuItem;
    private ListView lv;
    private MenuItemAdapter adapter;
    private int layoutId;
    private int productId;
    private int portionId;
    private int priceId;
    private int imgId;
    private View basketView;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        basketView = inflater.inflate(
                R.layout.basket_fragment, container, false);        
        
        return basketView;
    }
    
    @Override
    public void onAttach(Activity activity) {
        // TODO Auto-generated method stub
        super.onAttach(activity);
        setRetainInstance(true);
        layoutId = R.layout.basket_list;
        productId = R.id.basketProduct;
        portionId = R.id.portion;
        priceId = R.id.basketPrice;
        imgId = R.id.imgBasket;
        menuItem = new ArrayList<BaseOfMenuItems>();
        lv = (ListView) activity.findViewById(R.id.basketlistview);
        
        adapter = new MenuItemAdapter(getActivity(), menuItem, layoutId,
                productId, 0, priceId, portionId, imgId);
        lv.setAdapter(adapter);
    }

    public void setMenuItem(BaseOfMenuItems mi) {

        menuItem.add(mi);

    }
}

Activity sınıfı;

package com.restaurantexample.main;

import com.restaurantexample.main.R;
import com.restaurantexample.menuitems.BaseOfMenuItems;
import com.restaurantexample.fragment.BasketFragment;
import com.restaurantexample.fragment.DiscountFragment;
import com.restaurantexample.fragment.MenuFragment;
import com.restaurantexample.listener.OnMenuItemPressListener;
import com.restaurantexample.listener.RestaurantTabListener;

import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar.Tab;
import android.view.Menu;
import android.view.MenuInflater;

public class RestaurantMainPage extends ActionBarActivity implements OnMenuItemPressListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        ActionBar actBar = getSupportActionBar();
        actBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        actBar.setDisplayShowTitleEnabled(true);
        
        Tab restMenuTab = actBar.newTab();
        restMenuTab.setText("Меню");
        restMenuTab.setTabListener(new RestaurantTabListener<MenuFragment>(this, "menu", MenuFragment.class));
        actBar.addTab(restMenuTab);
        
        Tab discountTab = actBar.newTab();
        discountTab.setText("%");
        discountTab.setTabListener(new RestaurantTabListener<DiscountFragment>(this, "discount", DiscountFragment.class));
        actBar.addTab(discountTab);
        
        Tab basketTab = actBar.newTab();
        basketTab.setText("Корзина");
        basketTab.setTabListener(new RestaurantTabListener<BasketFragment>(this, "basket", BasketFragment.class));
        actBar.addTab(basketTab);
        
        if (savedInstanceState != null) {
            int savedIndex = savedInstanceState.getInt("index", 0);
            getSupportActionBar().setSelectedNavigationItem(savedIndex);
        }
    }
    
    @Override
    protected void onSaveInstanceState(Bundle outState) {
        // TODO Auto-generated method stub
        super.onSaveInstanceState(outState);
        outState.putInt("index", getSupportActionBar().getSelectedNavigationIndex());        
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.restaurant_main_page, menu);
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public void onMenuItemPressed(BaseOfMenuItems mi) {
        // TODO Auto-generated method stub
        BasketFragment bf = (BasketFragment) getSupportFragmentManager().findFragmentById(R.id.basketlistview);
        bf.setMenuItem(mi);
    }
    
}

Adapter sınıfı;

package com.restaurantexample.adapter;

import java.util.List;

import com.restaurantexample.menuitems.BaseOfMenuItems;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class MenuItemAdapter extends BaseAdapter{
    
    private Context context;
    private List<BaseOfMenuItems> list;
    private LayoutInflater inflater;
    private int layoutId;
    private int productId;
    private int amountId;
    private int priceId;
    private int portionId;
    private int imgId;

    public MenuItemAdapter(Context context, List<BaseOfMenuItems> list,
            int layoutId, int productId, int amountId, int priceId, int portionId, int imgId) {
        this.context = context;
        this.list = list;
        this.layoutId = layoutId;
        this.productId = productId;
        this.amountId = amountId;
        this.priceId = priceId;
        this.portionId = portionId;
        this.imgId = imgId;
        
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return list.size();
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return list.get(position);
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        TextView product, volume, price, portion;
        ImageView img;
        
        View itemView = convertView;
        inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        
        if(convertView == null) {
            itemView = inflater.inflate(layoutId, parent, false);
        }
        
        if (portionId == 0) {
            volume = (TextView) itemView.findViewById(amountId);
            volume.setText(list.get(position).getAmount());
        } else if (amountId == 0){
            portion = (TextView) itemView.findViewById(portionId);
            portion.setText(list.get(position).getPortion());
        }
        
        product = (TextView) itemView.findViewById(productId);
        product.setText(list.get(position).getProduct());
        
        price = (TextView) itemView.findViewById(priceId);
        price.setText("" + list.get(position).getPrice());
        
        img= (ImageView) itemView.findViewById(imgId);
        img.setImageResource(list.get(position).getImage());

        return itemView;
    }
    
}

Ve aldığım hata çıktısı;

10-05 10:11:17.674: E/AndroidRuntime(275): FATAL EXCEPTION: main
10-05 10:11:17.674: E/AndroidRuntime(275): java.lang.NullPointerException
10-05 10:11:17.674: E/AndroidRuntime(275):   at com.restaurantexample.fragment.DrinksFragment.onItemClick(DrinksFragment.java:103)
10-05 10:11:17.674: E/AndroidRuntime(275):     at android.widget.AdapterView.performItemClick(AdapterView.java:284)
10-05 10:11:17.674: E/AndroidRuntime(275):     at android.widget.ListView.performItemClick(ListView.java:3382)
10-05 10:11:17.674: E/AndroidRuntime(275):     at android.widget.AbsListView$PerformClick.run(AbsListView.java:1696)
10-05 10:11:17.674: E/AndroidRuntime(275):     at android.os.Handler.handleCallback(Handler.java:587)
10-05 10:11:17.674: E/AndroidRuntime(275):     at android.os.Handler.dispatchMessage(Handler.java:92)
10-05 10:11:17.674: E/AndroidRuntime(275):     at android.os.Looper.loop(Looper.java:123)
10-05 10:11:17.674: E/AndroidRuntime(275):     at android.app.ActivityThread.main(ActivityThread.java:4627)
10-05 10:11:17.674: E/AndroidRuntime(275):     at java.lang.reflect.Method.invokeNative(Native Method)
10-05 10:11:17.674: E/AndroidRuntime(275):     at java.lang.reflect.Method.invoke(Method.java:521)
10-05 10:11:17.674: E/AndroidRuntime(275):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
10-05 10:11:17.674: E/AndroidRuntime(275):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
10-05 10:11:17.674: E/AndroidRuntime(275):     at dalvik.system.NativeStart.main(Native Method)

Bir haftadır bu sorunu çözmeye çalışıyorum. Yardımlarınız için şimdiden teşekkürler.