回收器视图在适配器外部更改项目颜色

Question

目前我正在尝试弄清楚如何在适配器外部更改RecyclerView项目颜色。我只是在操纵位置，工作正常！但是我必须滑动页面进行颜色更新，我不知道我应该怎么做才能解决这个问题。

检查我的代码：

主活动.java

...
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
...

adapter = new viewPagerAdapter(getSupportFragmentManager());
//Add fragments here
adapter.addFragment(new fragmentList(), ""); //Lista de música
adapter.addFragment(new fragmentFrequent(), ""); //Frequentes
adapter.addFragment(new fragmentPlayList(), ""); //Playlist
viewPager.setAdapter(adapter);
tabLayout.setupWithViewPager(viewPager);
player_prev = findViewById(R.id.prev);
player_prev.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if ((currentPos-1) > 0) {
killMediaPlayer();
initAudio(getApplicationContext(), 
RecyclerViewAdapter.mData.get(currentPos - 1).getURL());
currentPos -= 1;

RecyclerViewAdapter.OldselectedPos = RecyclerViewAdapter.selectedPos;
RecyclerViewAdapter.selectedPos = currentPos;
adapter.notifyDataSetChanged();
}
});
...
}

回收器视图适配器.java

package etes.xdda.music;
import android.app.Dialog;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.support.v4.content.ContextCompat;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import java.util.List;

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder> implements View.OnClickListener{

MainActivity activity;
static List<mList> mData;
Dialog myDialog;
public static int selectedPos = RecyclerView.NO_POSITION;
public static int OldselectedPos = RecyclerView.NO_POSITION;
private LinearLayout menu_dialog, menu_dialog2;
public static TextView song_detail;
public RecyclerViewAdapter(MainActivity activity, List<mList> mData) {
this.activity = activity;
this.mData = mData;
}
@Override
public void onClick(View view) { }
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v;
v = LayoutInflater.from(activity).inflate(R.layout.item_list, parent, false);
final MyViewHolder vHolder = new MyViewHolder(v);
// Dialog ini
myDialog = new Dialog(activity);
myDialog.setContentView(R.layout.dialog);
myDialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
vHolder.item_play.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
TextView dialog_name_tv = myDialog.findViewById(R.id.dialog_name_id);
TextView dialog_phone_tv = myDialog.findViewById(R.id.dialog_author_id);
ImageView dialog_contact_img = myDialog.findViewById(R.id.dialog_img);
dialog_name_tv.setText(mData.get(vHolder.getAdapterPosition()).getName());
dialog_phone_tv.setText(mData.get(vHolder.getAdapterPosition()).getPhone());
dialog_contact_img.setImageResource(mData.get(vHolder.getAdapterPosition()).getPhoto());
//Toast.makeText(mContext, "Test click "+String.valueOf(vHolder.getAdapterPosition()), Toast.LENGTH_SHORT).show();
myDialog.show();
}
});
vHolder.menu_play.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
OldselectedPos = selectedPos;
selectedPos = vHolder.getAdapterPosition();
notifyItemChanged(selectedPos);
notifyItemChanged(OldselectedPos);

menu_dialog = v.getRootView().findViewById(R.id.menu_dialog);
menu_dialog.setVisibility(v.VISIBLE);
menu_dialog2 = v.getRootView().findViewById(R.id.menu_dialog2);
menu_dialog2.setVisibility(v.VISIBLE);
song_detail = v.getRootView().findViewById(R.id.song_detail);
song_detail.setVisibility(v.VISIBLE);

String newName;
newName = mData.get(vHolder.getAdapterPosition()).getName();
if (newName.length() > 42) {
newName = newName.substring(0, 38) + "...";
}
song_detail.setText(newName);
activity.killMediaPlayer();
activity.initAudio(v.getContext(), mData.get(vHolder.getAdapterPosition()).getURL());
activity.setMargins(v.getRootView().findViewById(R.id.viewpager_id), 0,0,0,205);
activity.updateNotificationBar("mzPlay", mData.get(vHolder.getAdapterPosition()).getName());
MainActivity.currentPos =  vHolder.getAdapterPosition();
}
});
return vHolder;
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
holder.tv_name.setText(mData.get(position).getName());
holder.tv_author.setText(mData.get(position).getPhone());
holder.img.setImageResource(mData.get(position).getPhoto());
//Toast.makeText(activity, String.valueOf(holder), Toast.LENGTH_LONG).show();
if(selectedPos == position){
holder.itemView.setBackgroundColor(Color.parseColor("#373737"));
}
else
{
holder.itemView.setBackgroundColor(Color.parseColor("#212121"));
}
}

@Override
public int getItemCount() {
return mData.size();
}

public static class MyViewHolder extends RecyclerView.ViewHolder {
private ImageButton item_play;
private LinearLayout menu_play;
private TextView tv_name;
private TextView tv_author;
private ImageView img;
public MyViewHolder(View itemView) {
super(itemView);
item_play = itemView.findViewById(R.id.info_id);
menu_play = itemView.findViewById(R.id.list_item_id);
tv_name = itemView.findViewById(R.id.name_list);
tv_author = itemView.findViewById(R.id.author_list);
img = itemView.findViewById(R.id.img_music);
}
}
}

视频：https://ntcdn.stream/20181009_2342010.mp4

问题是：我必须滑动页面才能更新项目颜色，如何在不滑动页面的情况下更新颜色？

Answer 1

将andoid 类存储在静态变量中确实是一个非常糟糕的做法。您应该使用非静态字段以常规方式与适配器交互，例如：

//This will go in your onCreate() for example
MyAdapter adapter = new MyAdapter(parameters);
...
adapter.highligtedItemPosition = 10;
adapter.notifyItemChanged(10);

稍后在你的 onBindViewHolder(( 根据你想要设置的背景做出反应：

if(position == highligtedItemPosition ){
holder.itemView.setBackgroundColor(Color.parseColor("#373737"));
}
else{
holder.itemView.setBackgroundColor(Color.parseColor("#212121"));
}

在此示例中，您必须添加一个整数字段：

int highligtedItemPosition;

到您的适配器以存储要更改其颜色的项目的位置。

更新：您没有从您的活动中调用 notifyItemChange(( 或 notifyDataSetChanged((，因此适配器需要"等待"滚动操作来"查看"更改。您应该从player_prev的 OnClickListener 调用 notifyItemChange(( 或 notifyDataSetChanged((。因此，适配器将立即反映更改。