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我想编写我自己的recyclerview slector算法。到目前为止，除了处理第一个选择之外，我成功地部分编写了代码。基本上我想设置背景为蓝色选择的项目，白色在别处（与ListView的setSelection相同）。RecyclerView抽屉 - 设置选择
所以，这个想法是：
- 设置在适配器的onCreateViewHolder方法的第一个元素蓝色背景。
- 在ActivityMain，定义一个intance查看变量navMenuSelection存储当前选择
- 在recyclerView的onclick监听器，设置点击视图蓝，背景navMenuSelection，为白色的背景，并更新navMenuSelection到点击视图
所有工作除外： 1.无法用第一个视图初始化navMenuSelection。试图用mDrawerLayout.getChildAt（0）在onPostCreate方法，但返回null
任何想法将不胜感激。
public class ActivityMain extends AppCompatActivity {
private View navMenuSelection = null; // Select current view
protected void onCreate(Bundle savedInstanceState) {
// ALL THE CODES TO DEFINE RECYCLERVIEW
mRecyclerView.addOnItemTouchListener(new RecycleTouchListener(this, new ClickListner() {
@Override
public void onClick(View view, int position) {
if(view != navMenuSelection){
setNavItemSelected(view);
removeNavItemSelected(navMenuSelection);
navMenuSelection = view;
mDrawerLayout.closeDrawers();
}
}
}));
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
mDrawerToggle.syncState();
navMenuSelection = mDrawerLayout.getChildAt(0);
}
@Override
public void onSaveInstanceState(Bundle savedInstanceState){
//savedInstanceState.put???("currselection", navMenuSelection); // HOW TO DO THAT
super.onSaveInstanceState(savedInstanceState);
}
public void setNavItemSelected(View v){
if(v!= null) {
v.setBackgroundColor(R.color.BLUE));
}
}
public void removeNavItemSelected(View v){
if(v!= null) {
v.setBackgroundColor(R.color.WHITE));
}
}
}
适配器类别（移动onClick事件后，适配器）
public class NavDrawerAdapter extends RecyclerView.Adapter<NavDrawerAdapter.ViewHolder> {
private String[] mNavTitles; // stores title
private int[] mIcons; // stores icon
private Context context;
private int oldpostion = 0;
public NavDrawerAdapter(Context context, String Titles[], int[] Icons){
this.context = context;
mNavTitles = Titles;
mIcons = Icons;
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView textView;
ImageView imageView;
public ViewHolder (View itemView) {
super(itemView);
textView = (TextView) itemView.findViewById(R.id.title);
imageView = (ImageView) itemView.findViewById(R.id.icon);
}
}
@Override
public NavDrawerAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.navdrawer_item,parent,false);
return new ViewHolder(v,viewType);
}
@Override
public void onBindViewHolder(NavDrawerAdapter.ViewHolder holder, final int position) {
holder.textView.setText(mNavTitles[position]);
holder.imageView.setImageResource(mIcons[position]);
if(position == 0) {
setNavItemSelected(holder.itemView);
}
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(position != oldpostion){
setNavItemSelected(v);
//removeNavItemSelected(OLD VIEW);
oldpostion = position;
}
}
});
}
@Override
public int getItemCount() {
return mNavTitles.length;
}
@Override
public int getItemViewType(int position) {
return 1;
}
public void setNavItemSelected(View v){
if(v!= null) {
v.setBackgroundColor(context.getResources().getColor(R.color.navdrawer_item_selected_bg));
TextView tview = (TextView) v.findViewById(R.id.title);
tview.setTextColor(context.getResources().getColor(R.color.navdrawer_item_selected_text));
}
}
public void removeNavItemSelected(View v){
if(v!= null) {
v.setBackgroundResource(R.drawable.list_selector_nav_drawer);
TextView tview = (TextView) v.findViewById(R.id.title);
tview.setTextColor(context.getResources().getColorStateList(R.color.list_selector_nav_drawer_text));
}
}
}
更好地把它放在recyclerview的适配器上。显示适配器代码 – Genevieve
right ur ..已将代码移至适配器..但是，无法从位置获取oldviewholder。 – abdfahim
显示适配器的代码 – Genevieve