什么是 SortedList<T>使用 RecyclerView.Adapter? [英] What is the SortedList<T> working with RecyclerView.Adapter?
问题描述
Android 支持库 22.1 已于昨天发布.v4 支持库和 v7 中添加了许多新功能，其中 android.support.v7.util.SortedList 引起了我的注意.
Android Support Library 22.1 was released yesterday. Many new features were added into the v4 support library and v7, among which android.support.v7.util.SortedList<T> draws my attention.
据说，SortedList是一种新的数据结构，配合RecyclerView.Adapter，维护提供的item的添加/删除/移动/更改动画回收器视图.这听起来像是 ListView 中的 List 但似乎更高级和强大.
It's said that, SortedList is a new data structure, works with RecyclerView.Adapter, maintains the item added/deleted/moved/changed animations provided by RecyclerView. It sounds like a List<T> in a ListView but seems more advanced and powerful.
那么，SortedList 和 List 有什么区别?我怎样才能有效地使用它?如果是这样，SortedList 对 List 的执行是什么?有人可以发布一些样本吗?
So, what is the difference between SortedList<T> and List<T>? How could I use it efficiently? What's the enforcement of SortedList<T> over List<T> if it is so? Could somebody post some samples of it?
任何提示或代码将不胜感激.提前致谢.
Any tips or codes will be appreciated. Thanks in advance.
推荐答案
SortedList 在 v7 支持库 中.
一个 SortedList 实现，可以保持项目有序，也可以通知列表中的更改，以便它可以绑定到RecyclerView.Adapter.
A
SortedListimplementation that can keep items in order and also notify for changes in the list such that it can be bound to aRecyclerView.Adapter.
它使用 compare(Object, Object) 方法保持项目有序，并且使用二分搜索来检索项目.如果您的排序标准项目可能会更改，请确保在编辑时调用适当的方法避免数据不一致.
It keeps items ordered using the compare(Object, Object) method and
uses binary search to retrieve items. If the sorting criteria of your
items may change, make sure you call appropriate methods while editing
them to avoid data inconsistencies.
您可以通过SortedList.Callback 参数.
下面是SortedList的使用示例，我觉得是你想要的，看一看，享受吧！
Here below is a sample of use of SortedList, I think it is what you want, take a look at it and enjoy!
public class SortedListActivity extends ActionBarActivity {
private RecyclerView mRecyclerView;
private LinearLayoutManager mLinearLayoutManager;
private SortedListAdapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sorted_list_activity);
mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
mRecyclerView.setHasFixedSize(true);
mLinearLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLinearLayoutManager);
mAdapter = new SortedListAdapter(getLayoutInflater(),
new Item("buy milk"), new Item("wash the car"),
new Item("wash the dishes"));
mRecyclerView.setAdapter(mAdapter);
mRecyclerView.setHasFixedSize(true);
final EditText newItemTextView = (EditText) findViewById(R.id.new_item_text_view);
newItemTextView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView textView, int id, KeyEvent keyEvent) {
if (id == EditorInfo.IME_ACTION_DONE &&
(keyEvent == null || keyEvent.getAction() == KeyEvent.ACTION_DOWN)) {
final String text = textView.getText().toString().trim();
if (text.length() > 0) {
mAdapter.addItem(new Item(text));
}
textView.setText("");
return true;
}
return false;
}
});
}
private static class SortedListAdapter extends RecyclerView.Adapter<TodoViewHolder> {
SortedList<Item> mData;
final LayoutInflater mLayoutInflater;
public SortedListAdapter(LayoutInflater layoutInflater, Item... items) {
mLayoutInflater = layoutInflater;
mData = new SortedList<Item>(Item.class, new SortedListAdapterCallback<Item>(this) {
@Override
public int compare(Item t0, Item t1) {
if (t0.mIsDone != t1.mIsDone) {
return t0.mIsDone ? 1 : -1;
}
int txtComp = t0.mText.compareTo(t1.mText);
if (txtComp != 0) {
return txtComp;
}
if (t0.id < t1.id) {
return -1;
} else if (t0.id > t1.id) {
return 1;
}
return 0;
}
@Override
public boolean areContentsTheSame(Item oldItem,
Item newItem) {
return oldItem.mText.equals(newItem.mText);
}
@Override
public boolean areItemsTheSame(Item item1, Item item2) {
return item1.id == item2.id;
}
});
for (Item item : items) {
mData.add(item);
}
}
public void addItem(Item item) {
mData.add(item);
}
@Override
public TodoViewHolder onCreateViewHolder(final ViewGroup parent, int viewType) {
return new TodoViewHolder (
mLayoutInflater.inflate(R.layout.sorted_list_item_view, parent, false)) {
@Override
void onDoneChanged(boolean isDone) {
int adapterPosition = getAdapterPosition();
if (adapterPosition == RecyclerView.NO_POSITION) {
return;
}
mBoundItem.mIsDone = isDone;
mData.recalculatePositionOfItemAt(adapterPosition);
}
};
}
@Override
public void onBindViewHolder(TodoViewHolder holder, int position) {
holder.bindTo(mData.get(position));
}
@Override
public int getItemCount() {
return mData.size();
}
}
abstract private static class TodoViewHolder extends RecyclerView.ViewHolder {
final CheckBox mCheckBox;
Item mBoundItem;
public TodoViewHolder(View itemView) {
super(itemView);
mCheckBox = (CheckBox) itemView;
mCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (mBoundItem != null && isChecked != mBoundItem.mIsDone) {
onDoneChanged(isChecked);
}
}
});
}
public void bindTo(Item item) {
mBoundItem = item;
mCheckBox.setText(item.mText);
mCheckBox.setChecked(item.mIsDone);
}
abstract void onDoneChanged(boolean isChecked);
}
private static class Item {
String mText;
boolean mIsDone = false;
final public int id;
private static int idCounter = 0;
public Item(String text) {
id = idCounter ++;
this.mText = text;
}
}
}
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