由於在 RecyclerView 內，不像之前的 ListView 有 setOnItemClickListener 可以用，而需要 Item Click 功能的需求很高。
這邊我就放一下我目前在用的寫法，但是請注意這僅是適用在我大部分的情境，你情況不同的話可能會遇到一些限制。 例如：你想要在 RecyclerView 中間插個廣告。這時候就請自己變形了。
先輕鬆一點，看個 OnItemClickListener，會傳 View 過來就是為了利用 id 可以知道是點到哪一個元件。如果一個 Row 上有不同的動作就可以善加利用。
public abstract class OnItemClickListener<T> {
public abstract void onClick(int index, View source, T data);
public final static OnItemClickListener DUMMY = new OnItemClickListener<Object>() {
@Override
public void onClick(int index, View source, Object data) {
}
};
}
最關鍵的是 ClickableRecyclerViewAdapter 定義共用的功能，並且利用泛型規定好資料型別，方便在 OnItemViewClick 取出來使用。
public abstract class ClickableRecyclerViewAdapter<T, VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {
OnItemClickListener itemClickListener = OnItemClickListener.DUMMY;
//定義在 ids.xml 內，避免被人手殘弄到重複。
public final int DATA_INDEX = R.id.tag_row_data;
public final int POSITION_INDEX = R.id.tag_row_position;
final View.OnClickListener clickListener = new View.OnClickListener() {
@Override
public void onClick(View v) {
//利用泛型進行 cast，方便在接的時候直接取用不用再轉一次。
itemClickListener.onClick((Integer) v.getTag(POSITION_INDEX), v, (T) v.getTag(DATA_INDEX));
}
};
//預先準備好空的 List，讓 getItemCount 不會 NullPointer
protected List<T> data = Collections.emptyList();
//用範型限定傳入的型別，加上 @NonNull 警告不要傳 null 進來。
public ClickableRecyclerViewAdapter setData(@NonNull List<T> data) {
this.data = data;
notifyDataSetChanged();
return this;
}
//定義類似 ListView 的 Adapter 使用的 getItem，方便在 onBindViewHolder 使用。
public T getItem(int position) {
return data.get(position);
}
@Override
public int getItemCount() {
return data.size();
}
public ClickableRecyclerViewAdapter setOnItemClickListener(OnItemClickListener<T> listener) {
this.itemClickListener = null == listener ? OnItemClickListener.DUMMY : listener;
return this;
}
//在 Bind 時只要呼叫這個功能就可以在某個 View 加上 Click 的接收。
protected void enableClickOnView(int position, View view, T data) {
view.setTag(POSITION_INDEX, position);
view.setTag(DATA_INDEX, data);
view.setOnClickListener(clickListener);
}
}既然定義好了就只要單純的跟平常使用 RecyclerView 一樣，針對要啟用點擊的 View 去呼叫 enableClickOnView
public class UserRecyclerViewAdapter extends ClickableRecyclerViewAdapter<User, UserRecyclerViewAdapter.ViewHolder> {
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
final LayoutInflater inflater = LayoutInflater.from(parent.getContext());
final View row = inflater.inflate(ViewHolder.LAYOUT_ID, parent, false);
return new ViewHolder(row);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
final User user = getItem(position);
holder.rowNumber.setText("" + position);
holder.name.setText(user.name);
holder.age.setText("" + user.age);
holder.job.setText(user.jobTitle);
holder.gender.setText(user.gender.strResId);
//啟用點整列
enableClickOnView(position, holder.itemView, user);
//啟用點旁邊的編輯鈕
enableClickOnView(position, holder.editButton, user);
}
public static class ViewHolder extends RecyclerView.ViewHolder {
//此 ViewHolder 對應的 Layout
public final static int LAYOUT_ID = R.layout.row_user;
public final TextView rowNumber;
public final TextView name;
public final TextView age;
public final TextView gender;
public final TextView job;
public final View editButton;
public ViewHolder(View itemView) {
super(itemView);
rowNumber = (TextView) itemView.findViewById(R.id.row_number);
name = (TextView) itemView.findViewById(R.id.name);
age = (TextView) itemView.findViewById(R.id.age);
gender = (TextView) itemView.findViewById(R.id.gender);
job = (TextView) itemView.findViewById(R.id.job);
editButton = itemView.findViewById(R.id.edit);
}
}
}用起來就跟 ListView 很像，只是變成是在 Adapter 去做 setOnItemClickListener。利用 id 去分辨點到哪一個 View 就知道要做什麼處理。
public class MainActivity extends AppCompatActivity {
//DataSet
private final List<User> users = new ArrayList<>();
UserRecyclerViewAdapter adapter = new UserRecyclerViewAdapter();
RecyclerView list;
protected Toast toast;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
prepareData();
setupView();
}
private void prepareData() {
users.add(new User(1, "John", "CEO", 23, MALE));
users.add(new User(2, "Jack", "PM", 45, MALE));
users.add(new User(3, "Mary", "UI", 21, FEMALE));
users.add(new User(6, "Bob", "RD", 27, MALE));
users.add(new User(9, "Alice", "RD", 22, FEMALE));
users.add(new User(20, "Oak", "RD", 28, MALE));
users.add(new User(34, "Lora", "PM", 27, FEMALE));
users.add(new User(35, "Alec", "RD", 22, MALE));
users.add(new User(39, "Patricia", "RD", 26, FEMALE));
users.add(new User(41, "Valkry", "CTO", 40, FEMALE));
users.add(new User(43, "Mike", "RD", 36, MALE));
}
private void setupView() {
list = (RecyclerView) findViewById(R.id.list);
list.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));
list.setAdapter(adapter);
adapter.setData(users);
adapter.setOnItemClickListener(new OnItemClickListener<User>() {
@Override
public void onClick(int index, View source, User data) {
switch (source.getId()) {
case R.id.edit:
toast("Edit " + data.name);
break;
default:
toast("View " + data.name);
}
}
});
}
protected void toast(String text) {
if(null != toast) {
toast.cancel();
}
toast = Toast.makeText(this, text, Toast.LENGTH_SHORT);
toast.show();
}
}User 就…沒什麼好說的。
public class User {
//直接綁定 String Resource ID，作多國語言比較方便。
public enum Gender {
MALE(R.string.male),
FEMALE(R.string.female);
public final int strResId;
Gender(int strResId) {
this.strResId = strResId;
}
}
public final int id;
public final String name;
public final String jobTitle;
public final int age;
public final Gender gender;
public User(int id, String name, String jobTitle, int age, Gender gender) {
this.id = id;
this.name = name;
this.jobTitle = jobTitle;
this.age = age;
this.gender = gender;
}
}