我正在使用回收站视图实施导航栏，参考网站上提供的代码：http://www.android4devs.com/2015/01/how-to-make-material-design-sliding-tabs.html
在MainActivity.java中，调用以下行。
mAdapter = new MyAdapter(TITLES,ICONS,NAME,EMAIL,PROFILE);
mRecyclerView.setAdapter(mAdapter);
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);
我想知道在MyAdapter.java中以什么顺序调用哪些函数？ 这是MyAdapter.java的代码
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private static final int TYPE_HEADER = 0; // Declaring Variable to Understand which View is being worked on
// IF the view under inflation and population is header or Item
private static final int TYPE_ITEM = 1;
private String mNavTitles[]; // String Array to store the passed titles Value from MainActivity.java
private int mIcons[]; // Int Array to store the passed icons resource value from MainActivity.java
private String name; //String Resource for header View Name
private int profile; //int Resource for header view profile picture
private String email; //String Resource for header view email
MyAdapter(String Titles[], int Icons[], String Name, String Email, int Profile) { // MyAdapter Constructor with titles and icons parameter
// titles, icons, name, email, profile pic are passed from the main activity as we
mNavTitles = Titles; //have seen earlier
mIcons = Icons;
name = Name;
email = Email;
profile = Profile; //here we assign those passed values to the values we declared here
//in adapter
}
// Creating a ViewHolder which extends the RecyclerView View Holder
// ViewHolder are used to to store the inflated views in order to recycle them
public static class ViewHolder extends RecyclerView.ViewHolder {
int Holderid;
TextView textView;
ImageView imageView;
ImageView profile;
TextView Name;
TextView email;
public ViewHolder(View itemView, int ViewType) { // Creating ViewHolder Constructor with View and viewType As a parameter
super(itemView);
// Here we set the appropriate view in accordance with the the view type as passed when the holder object is created
if (ViewType == TYPE_ITEM) {
textView = (TextView) itemView.findViewById(R.id.rowText); // Creating TextView object with the id of textView from item_row.xml
imageView = (ImageView) itemView.findViewById(R.id.rowIcon);// Creating ImageView object with the id of ImageView from item_row.xml
Holderid = 1; // setting holder id as 1 as the object being populated are of type item row
} else {
Name = (TextView) itemView.findViewById(R.id.name); // Creating Text View object from header.xml for name
email = (TextView) itemView.findViewById(R.id.email); // Creating Text View object from header.xml for email
profile = (ImageView) itemView.findViewById(R.id.circleView);// Creating Image view object from header.xml for profile pic
Holderid = 0; // Setting holder id = 0 as the object being populated are of type header view
}
}
}
//Below first we ovverride the method onCreateViewHolder which is called when the ViewHolder is
//Created, In this method we inflate the item_row.xml layout if the viewType is Type_ITEM or else we inflate header.xml
// if the viewType is TYPE_HEADER
// and pass it to the view holder
@Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_ITEM) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_item, parent, false); //Inflating the layout
ViewHolder vhItem = new ViewHolder(v, viewType); //Creating ViewHolder and passing the object of type view
return vhItem; // Returning the created object
//inflate your layout and pass it to view holder
} else if (viewType == TYPE_HEADER) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.header, parent, false); //Inflating the layout
ViewHolder vhHeader = new ViewHolder(v, viewType); //Creating ViewHolder and passing the object of type view
return vhHeader; //returning the object created
}
return null;
}
//Next we override a method which is called when the item in a row is needed to be displayed, here the int position
// Tells us item at which position is being constructed to be displayed and the holder id of the holder object tell us
// which view type is being created 1 for item row
@Override
public void onBindViewHolder(MyAdapter.ViewHolder holder, int position) {
if (holder.Holderid == 1) { // as the list view is going to be called after the header view so we decrement the
// position by 1 and pass it to the holder while setting the text and image
holder.textView.setText(mNavTitles[position - 1]); // Setting the Text with the array of our Titles
holder.imageView.setImageResource(mIcons[position - 1]);// Settimg the image with array of our icons
} else {
holder.profile.setImageResource(profile); // Similarly we set the resources for header view
holder.Name.setText(name);
holder.email.setText(email);
}
}
// This method returns the number of items present in the list
@Override
public int getItemCount() {
return mNavTitles.length + 1; // the number of items in the list will be +1 the titles including the header view.
}
// With the following method we check what type of view is being passed
@Override
public int getItemViewType(int position) {
if (isPositionHeader(position))
return TYPE_HEADER;
return TYPE_ITEM;
}
private boolean isPositionHeader(int position) {
return position == 0;
}
}
我通过阅读评论了解了特定功能的作用，我想知道它们被调用的顺序是什么？ 有人能帮助我理解这个吗？ 感谢。
答案 0 :(得分：6)
调用适配器内部方法的顺序如下：
RecyclerView尝试从其回收（或报废）视图持有者池中抓取某个位置的视图持有者。getItemViewType表示要填写的位置RecyclerView视图没有此项目类型的可用视图持有者，则会调用onCreateViewHolder以便为此项目类型创建新的视图持有者。onBindViewHolder来为视图持有者设置正确的数据。getItemCount将用于确保RecyclerView不会尝试填充超出数据源限制的视图持有者。