将值从 recyclerview cardview 传递到 deautilactivity onitemclick

Question

我是 android 开发新手，我一直在尝试将值从 recyclerview cardview 传递到 detailActivity，在搜索了几个小时后我想出了这段代码，在实现这段代码之前我能够查看MainActivity上的所有cardview，现在当我实现这个代码时，应用程序在启动应用程序时崩溃，事件日志。

这是我的 Fragment，其中包含 Firebaserecycler Adapter 和 viewholder 类：

public class MakingFragment extends Fragment {
    private FloatingActionButton fab;

    ScaleAnimation shrinkAnim;
    private RecyclerView mRecyclerView;
    private LinearLayoutManager mLayoutManager;
    private TextView tvNoMovies;

    Context c;
    ArrayList<Food> spacecrafts;

    //Getting reference to Firebase Database
    FirebaseDatabase database = FirebaseDatabase.getInstance();
    DatabaseReference mDatabaseReference = database.getReference();

    private static final String userId = "53";

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.making,container,false);

        //Initializing our Recyclerview
        mRecyclerView = (RecyclerView) v.findViewById(R.id.my_recycler_view);
        tvNoMovies = (TextView) v.findViewById(R.id.tv_no_movies);

        //scale animation to shrink floating actionbar
        shrinkAnim = new ScaleAnimation(1.15f, 0f, 1.15f, 0f, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);

        if (mRecyclerView != null) {
            //to enable optimization of recyclerview
            mRecyclerView.setHasFixedSize(true);
        }
        //using staggered grid pattern in recyclerview
        mLayoutManager = new LinearLayoutManager(getActivity());
        mRecyclerView.setLayoutManager(mLayoutManager);

        mLayoutManager.setReverseLayout(true); // to reverse the items updating on recycleview
        mLayoutManager.setStackFromEnd(true);  // to scroll from top when layout is reversed

        //Say Hello to our new FirebaseUI android Element, i.e., FirebaseRecyclerAdapter
        FirebaseRecyclerAdapter<Food,FoodViewHolder> adapter = new FirebaseRecyclerAdapter<Food, FoodViewHolder>(
                Food.class,
                R.layout.food_item,
                FoodViewHolder.class,

                //referencing the node where we want the database to store the data from our Object
                mDatabaseReference.child("users").child(userId).child("food").getRef()
        ) {
            @Override
            protected void populateViewHolder(FoodViewHolder viewHolder, final Food model, int position) {
                if(tvNoMovies.getVisibility()== View.VISIBLE){
                    tvNoMovies.setVisibility(View.GONE);
                }
                viewHolder.tvFoodName.setText(model.getFoodName());
                viewHolder.ratingBar.setRating(model.getFoodRating());
                viewHolder.tvFoodCategory.setText(model.getFoodCategory());
                viewHolder.tvFoodAvailableUpto.setText(model.getFoodAvailableUpto());
                viewHolder.tvFoodPrice.setText(model.getFoodPrice());
                Picasso.with(getActivity().getApplicationContext()).load(model.getFoodPoster()).into(viewHolder.ivFoodPoster);

                viewHolder.setItemClickListener(new ItemClickListener() {
                    @Override
                    public void onItemClick(int pos) {
                        //OPEN DETAI ACTIVITY
                        openDetailActivity(model.getFoodName(),model.getFoodCategory(),model.getFoodAvailableUpto(),model.getFoodPrice());
                    }
                });
            }
            @Override
            public int getItemCount() {
                return spacecrafts.size();
            }
            //OPEN DETAIL ACTIVITY
            private void openDetailActivity(String...details)
            {
                Intent i=new Intent(c,DetailActivity.class);
                i.putExtra("TITLE_KEY",details[0]);
                i.putExtra("CAT_KEY",details[1]);
                i.putExtra("AVAIL_KEY",details[2]);
                i.putExtra("PRI_KEY",details[3]);
                c.startActivity(i);
            }
        };
        mRecyclerView.setAdapter(adapter);

        fab = (FloatingActionButton) v.findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Intent launchactivity=new Intent(getActivity().getApplicationContext(),AddFoodDetailsActivity.class);
                startActivity(launchactivity);
                //animation being used to make floating actionbar disappear
                shrinkAnim.setDuration(400);
                fab.setAnimation(shrinkAnim);
                shrinkAnim.start();
                shrinkAnim.setAnimationListener(new Animation.AnimationListener() {
                    @Override
                    public void onAnimationStart(Animation animation) {

                    }

                    @Override
                    public void onAnimationEnd(Animation animation) {
                        //changing floating actionbar visibility to gone on animation end
                        fab.setVisibility(View.GONE);
                    }

                    @Override
                    public void onAnimationRepeat(Animation animation) {

                    }
                });
            }
        });
       return v;

    }

    public void onBackPressed() {
        getActivity().onBackPressed();
        if (fab.getVisibility() == View.GONE)
            fab.setVisibility(View.VISIBLE);
    }

    //ViewHolder for our Firebase UI
    public static class FoodViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        TextView tvFoodName;
        RatingBar ratingBar;
        ImageView ivFoodPoster;
        TextView tvFoodCategory;
        TextView tvFoodAvailableUpto;
        TextView tvFoodPrice;
        ImageView ivNextArrow;
        ItemClickListener itemClickListener;

        public FoodViewHolder(View v) {
            super(v);
            tvFoodName = (TextView) v.findViewById(R.id.tvName);
            ratingBar = (RatingBar) v.findViewById(R.id.rating_bar);
            ivFoodPoster = (ImageView) v.findViewById(R.id.imgThumb);
            tvFoodCategory = (TextView) v.findViewById(R.id.tvCategory);
            tvFoodAvailableUpto= (TextView) v.findViewById(R.id.tvavailable);
            tvFoodPrice = (TextView) v.findViewById(R.id.tvprice);
            ivNextArrow = (ImageView) v.findViewById(R.id.NextArrow);

            v.setOnClickListener(this);
        }
        public void setItemClickListener(ItemClickListener itemClickListener)
        {
            this.itemClickListener=itemClickListener;
        }
        @Override
        public void onClick(View view) {
            this.itemClickListener.onItemClick(this.getLayoutPosition());
        }
    }
}

这是我的 DetailActivity

public class DetailActivity extends AppCompatActivity {
    TextView nameTxt,catTxt,availTxt,priceTxt;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        nameTxt = (TextView) findViewById(R.id.titleTxt);
        catTxt= (TextView) findViewById(R.id.catTxt);
        availTxt = (TextView) findViewById(R.id.availTxt);
        priceTxt = (TextView) findViewById(R.id.pricesTxt);
        //GET INTENT
        Intent i=this.getIntent();
        //RECEIVE DATA
        String title=i.getExtras().getString("TITLE_KEY");
        String cat=i.getExtras().getString("CAT_KEY");
        String avail=i.getExtras().getString("AVAIL_KEY");
        String price=i.getExtras().getString("PRI_KEY");
        //BIND DATA
        nameTxt.setText(title);
        catTxt.setText(cat);
        availTxt.setText(avail);
        priceTxt.setText(price);
    }
}

请帮帮我，谢谢。

Answer 1

初始化oncreate()中的arraylist

spacecrafts= new ArrayList<>();

这些也在oncreate()

 database = FirebaseDatabase.getInstance();
 mDatabaseReference = database.getReference();

并检查航天器是否为空