如何正确地强调选择项目RecyclerView？ [英] How to properly highlight selected item on RecyclerView?

问题描述

我想使用RecyclerView卧式列表视图。我试图找出如何突出选择的项目。当我点击的项目之一，它被选中并正确highlited但是当我点击另一个第二个被用，哥哥突出。

下面是我的onClick功能：

  @覆盖
    公共无效的onClick（视图查看）{

        如果（selectedListItem！= NULL）{
             Log.d（TAG，selectedListItem+为getPosition（）++项目）;
            selectedListItem.setBackgroundColor（Color.RED）;
        }
        Log.d（TAG的onClick+为getPosition（）++项目）;
        viewHolderListener.onIndexChanged（为getPosition（））;
        selectedPosition =为getPosition（）;
        view.setBackgroundColor（Color.CYAN）;
        selectedListItem =图。
    }
 

下面是onBindViewHolder：

  @覆盖
公共无效onBindViewHolder（ViewHolder viewHolder，INT位置）{
    viewHolder.setItem（fruitsData [位置]）;
    如果（selectedPosition ==位置）
        viewHolder.itemView.setBackgroundColor（Color.CYAN）;
    其他
        viewHolder.itemView.setBackgroundColor（Color.RED）;

}
 

解决方案

我写了一个基本适配器类来自动处理项目选择了RecyclerView。只是从中获得您的适配器，并使用可绘制状态列表与state_selected，就像你要做一个列表视图做。

我有一个博客张贴在这里有关，但这里是code：

 公共抽象类TrackSelectionAdapter＆LT; VH延伸TrackSelectionAdapter.ViewHolder＆GT;扩展RecyclerView.Adapter＆LT; VH＆GT; {
    //开始与选定的第一个项目
    私人诠释focusedItem = 0;

    @覆盖
    公共无效onAttachedToRecyclerView（最终RecyclerView recyclerView）{
        super.onAttachedToRecyclerView（recyclerView）;

        //手柄键和键并试图移动选择
        recyclerView.setOnKeyListener（新View.OnKeyListener（）{
            @覆盖
            公共布尔onKey（视图V，INT关键code，KeyEvent的事件）{
                RecyclerView.LayoutManager LM = recyclerView.getLayoutManager（）;

                //返回false，如果滚动到的范围，让焦点移出列表
                如果（event.getAction（）== KeyEvent.ACTION_DOWN）{
                    如果（键code == KeyEvent.KEY code_DPAD_DOWN）{
                        返回tryMoveSelection（流明，1）;
                    }否则，如果（键code == KeyEvent.KEY code_DPAD_UP）{
                        返回tryMoveSelection（流明，-1）;
                    }
                }

                返回false;
            }
        }）;
    }

    私人布尔tryMoveSelection（RecyclerView.LayoutManager流明，INT方向）{
        INT tryFocusItem = focusedItem +方向;

        //如果仍然有效的范围内，移动选择，通知重绘，和滚动
        如果（tryFocusItem＆GT; = 0＆安培;＆安培; tryFocusItem＆其中; getItemCount（））{
            notifyItemChanged（focusedItem）;
            focusedItem = tryFocusItem;
            notifyItemChanged（focusedItem）;
            lm.scrollToPosition（focusedItem）;
            返回true;
        }

        返回false;
    }

    @覆盖
    公共无效onBindViewHolder（VH viewHolder，int i）以{
        //设置选中状态;使用状态列表绘制样式视图
        viewHolder.itemView.setSelected（focusedItem == I）;
    }

    公共类ViewHolder扩展RecyclerView.ViewHolder {
        公共ViewHolder（查看ItemView控件）{
            超（ItemView控件）;

            //处理项目的点击和设置选择
            itemView.setOnClickListener（新View.OnClickListener（）{
                @覆盖
                公共无效的onClick（视图v）{
                    //重绘旧的选择和新的
                    notifyItemChanged（focusedItem）;
                    focusedItem = getLayoutPosition（）;
                    notifyItemChanged（focusedItem）;
                }
            }）;
        }
    }
}
 

I am trying to use RecyclerView as horizontal listview. I am trying to figure out how to highlight selected item. When i click one of the item, it gets selected and it is highlited properly but when i click another one second one gets highlighted with the older one.

Here is my onClick function:

    @Override
    public void onClick(View view) {

        if(selectedListItem!=null){
             Log.d(TAG, "selectedListItem " + getPosition() + " " + item);
            selectedListItem.setBackgroundColor(Color.RED);
        }
        Log.d(TAG, "onClick " + getPosition() + " " + item);
        viewHolderListener.onIndexChanged(getPosition());
        selectedPosition = getPosition();
        view.setBackgroundColor(Color.CYAN); 
        selectedListItem = view;
    }

Here is onBindViewHolder:

@Override
public void onBindViewHolder(ViewHolder viewHolder, int position) {   
    viewHolder.setItem(fruitsData[position]);
    if(selectedPosition == position)
        viewHolder.itemView.setBackgroundColor(Color.CYAN);    
    else
        viewHolder.itemView.setBackgroundColor(Color.RED);

}

解决方案

I wrote a base adapter class to automatically handle item selection with a RecyclerView. Just derive your adapter from it and use drawable state lists with state_selected, like you would do with a list view.

I have a Blog Post Here about it, but here is the code:

public abstract class TrackSelectionAdapter<VH extends TrackSelectionAdapter.ViewHolder> extends RecyclerView.Adapter<VH> {
    // Start with first item selected
    private int focusedItem = 0;

    @Override
    public void onAttachedToRecyclerView(final RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);

        // Handle key up and key down and attempt to move selection
        recyclerView.setOnKeyListener(new View.OnKeyListener() {
            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                RecyclerView.LayoutManager lm = recyclerView.getLayoutManager();

                // Return false if scrolled to the bounds and allow focus to move off the list
                if (event.getAction() == KeyEvent.ACTION_DOWN) {
                    if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN) {
                        return tryMoveSelection(lm, 1);
                    } else if (keyCode == KeyEvent.KEYCODE_DPAD_UP) {
                        return tryMoveSelection(lm, -1);
                    }
                }

                return false;
            }
        });
    }

    private boolean tryMoveSelection(RecyclerView.LayoutManager lm, int direction) {
        int tryFocusItem = focusedItem + direction;

        // If still within valid bounds, move the selection, notify to redraw, and scroll
        if (tryFocusItem >= 0 && tryFocusItem < getItemCount()) {
            notifyItemChanged(focusedItem);
            focusedItem = tryFocusItem;
            notifyItemChanged(focusedItem);
            lm.scrollToPosition(focusedItem);
            return true;
        }

        return false;
    }

    @Override
    public void onBindViewHolder(VH viewHolder, int i) {
        // Set selected state; use a state list drawable to style the view
        viewHolder.itemView.setSelected(focusedItem == i);
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        public ViewHolder(View itemView) {
            super(itemView);

            // Handle item click and set the selection
            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    // Redraw the old selection and the new
                    notifyItemChanged(focusedItem);
                    focusedItem = getLayoutPosition();
                    notifyItemChanged(focusedItem);
                }
            });
        }
    }
} 

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