Question

我的recyclerview非常适合滚动，但当它包含两个以上的项目并点击最后一个项目或之前的那个项目给我错误的位置时这是并抛出一个NullPointerException这是我从适配器到监听器的整个代码。 我的代码：

public class ListAdapter extends RecyclerView.Adapter<ViewHolder> {

private List<ItemView> items;
private Context context;

public ListAdapter(List<ItemView> items, Context context) {
    this.items = items;
    this.context = context;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.item_style, parent, false);
    return new ViewHolder(view);
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    ItemView i = items.get(position);

    ViewHolder.setHeadText(i.getHead());
    ViewHolder.setScoreText(i.getContent());
}
@Override
public int getItemCount() {
    return items.size();
}

}

class ViewHolder extends RecyclerView.ViewHolder {
private RecyclerViewOnTouchItemListener.ClickListener clickListener;
private static TextView headText, urlText;
private ConstraintLayout itemLayout;

public ViewHolder(View itemView) {
    super(itemView);

    headText = (TextView) itemView.findViewById(R.id.list_item_header);
    urlText = (TextView) itemView.findViewById(R.id.list_item_content);
    itemLayout = (ConstraintLayout) itemView.findViewById(R.id.item_list);
    // itemLayout.setOnClickListener(this);
}


public static void setHeadText(String headText) {
    ViewHolder.headText.setText(headText);
}

public static void setScoreText(String scoreText) {
    ViewHolder.urlText.setText(scoreText);
}

public static String getHeadText(){return headText.getText().toString();}

public static String getUrlText(){return urlText.getText().toString();}

}

class RecyclerViewOnTouchItemListener implements RecyclerView.OnItemTouchListener {

private GestureDetector gestureDetector;
private ClickListener clickListener;

public RecyclerViewOnTouchItemListener(Context context, final RecyclerView recyclerView, final ClickListener clickListener) {
    this.clickListener = clickListener;
    gestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
        @Override
        public boolean onSingleTapUp(MotionEvent e) {
            return true;
        }

        @Override
        public void onLongPress(MotionEvent e) {
            View child = recyclerView.findChildViewUnder(e.getX(), e.getY());
            if (child != null && clickListener != null) {
                clickListener.onLongClick(child, recyclerView.getChildAdapterPosition(child));
            }
        }
    });
}
@Override
public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
    View child = rv.findChildViewUnder(e.getX(), e.getY());
    if (child != null && clickListener != null && gestureDetector.onTouchEvent(e)) {
        clickListener.onClick(child, rv.getChildAdapterPosition(child));
    }
    return false;
}
@Override
public void onTouchEvent(RecyclerView rv, MotionEvent e) { }
@Override
public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) { }

interface ClickListener {
    void onClick(View view, int position);
    void onLongClick(View view, int position);
}

}

这是包含recyclerview的活动：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_url_list);

    context = getApplicationContext();
    database = new DatabaseHelper(context);
    listOfUrl = (RecyclerView) findViewById(R.id.url_list);
    find = (Button) findViewById(R.id.findBtn);
    cancel = (Button) findViewById(R.id.cancelBtn);

    makeItPopUp();

    listOfUrl.setLayoutManager(new LinearLayoutManager(this));
    listOfUrl.setHasFixedSize(true);
    listOfUrl.addItemDecoration(new DividerItemDecoration(this, LinearLayoutManager.VERTICAL));
    adapter = new ListAdapter(fillList(), context);
    listOfUrl.setAdapter(adapter);
    adapter.notifyDataSetChanged();

    selectedItems = new ArrayList<Boolean>(Arrays.asList(new Boolean[listOfUrl.getAdapter().getItemCount()]));
    Collections.fill(selectedItems, Boolean.FALSE);

    listOfUrl.addOnItemTouchListener(
            new RecyclerViewOnTouchItemListener(this, listOfUrl
                    , new RecyclerViewOnTouchItemListener.ClickListener() {
                @Override
                public void onClick(View view, int position) {
                    if (selectedItems.get(position))
                        setItemSelectedState(false, position, Color.WHITE);
                    else
                        setItemSelectedState(true, position, Color.LTGRAY);
                }
                @Override
                public void onLongClick(View view, int position) {}

                private void setItemSelectedState(boolean isSelected, int position, int color) {
                    try {
                        listOfUrl.getChildAt(position).setBackgroundColor(color);
                        selectedItems.add(position, isSelected);
                    } catch (NullPointerException e) {
                        e.printStackTrace();
                    }
                }
            })
    );
    find.setOnClickListener(this);
    cancel.setOnClickListener(this); }

任何可以告诉我我做错了什么。

Answer 1

简单的解决方案，创建接口类：

public interface ListListener {
    void onClick(int pos);
    void onLongClick(int pos);
}

调整RecyclerViewAdapter类的内容：

public class ListAdapter extends RecyclerView.Adapter<ViewHolder> {

private ListListener listener;
private List<ItemView> items;
private Context context;

public ListAdapter(List<ItemView> items, Context context) {
    this.items = items;
    this.context = context;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.item_style, parent, false);
    return new ViewHolder(view);
}

public ItemView getItem(int pos) {
    return items.get(pos);
}

public void setListener(ListListener listener) {
    this.listener = listener;
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    ItemView i = items.get(position);

    holder.setHeadText(i.getHead());
    holder.setScoreText(i.getContent());

    holder.itemLayout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int pos = holder.getAdapterPosition();
                if (listener != null && pos != RecyclerView.NO_POSITION) {
                    listener.onClick(pos);
                }
            }
    });

    holder.itemLayout.setOnLongClickListener(new View.OnLongClickListener() {
                    @Override
                    public boolean onLongClick(View view) {
                        int pos = holder.getAdapterPosition();
                        if (pos != -1) {
                            if (listener != null) {
                                listener.onLongClick(getItem(pos));
                            }
                        }
                        return true;
                    }
                });
}

在您的Activity类中，我编辑了一些部分：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_url_list);

    context = getApplicationContext();
    database = new DatabaseHelper(context);
    listOfUrl = (RecyclerView) findViewById(R.id.url_list);
    find = (Button) findViewById(R.id.findBtn);
    cancel = (Button) findViewById(R.id.cancelBtn);

    makeItPopUp();

    listOfUrl.setLayoutManager(new LinearLayoutManager(this));
    listOfUrl.setHasFixedSize(true);
    listOfUrl.addItemDecoration(new DividerItemDecoration(this, LinearLayoutManager.VERTICAL));
    adapter = new ListAdapter(fillList(), context);
    adapter.setListener(new SelectCountryDialogListener() {
            @Override
            public void onClick(int pos) {
                ItemView item = adapter.getItem(pos);
            }

            @Override
            public void onLongClick(int pos) {
                ItemView item = adapter.getItem(pos);
            }
        });
    listOfUrl.setAdapter(adapter);

    selectedItems = new ArrayList<Boolean>(Arrays.asList(new Boolean[listOfUrl.getAdapter().getItemCount()]));
    Collections.fill(selectedItems, Boolean.FALSE);

    find.setOnClickListener(this);
    cancel.setOnClickListener(this); 
}

我很确定，现在对你来说很容易。只是为了实现onClick和onLongClick方法的功能。

错误的recyclerview项目位置

1 个答案: