2019独角兽企业重金招聘Python工程师标准>>> 
今天来说说DataBinding在列表RecyclerView中的使用
列表绑定
App中经常用到列表展示，Data Binding在列表中一样可以扮演重要的作用，直接绑定数据和事件到每一个列表的item。
RecyclerView
过去我们往往会使用ListView、GridView、或者GitHub上一些自定义的View来做瀑布流。自从RecyclerView出现后，我们有了新选择，只需要使用LayoutManager就可以。
RecyclerView内置的垃圾回收，ViewHolder、ItemDecoration装饰器机制都让我们可以毫不犹豫地替换掉原来的ListView和GridView。
主布局：
item布局：
ViewHolder
public class RecyclerViewHolder extends RecyclerView.ViewHolder {
public Item8MvvmBinding getItem8MvvmBinding() {
return item8MvvmBinding;
}
public void setItem8MvvmBinding(Item8MvvmBinding item8MvvmBinding) {
this.item8MvvmBinding = item8MvvmBinding;
}
//这里只要给RecyclerView.ViewHolder返回一个view就可以，所以我们将构造方法中传入databinding
Item8MvvmBinding item8MvvmBinding;
public RecyclerViewHolder(Item8MvvmBinding item8MvvmBinding) {
super(item8MvvmBinding.getRoot());
this.item8MvvmBinding = item8MvvmBinding;
}
}adapter：
public class RecyclerViewAdapter extends RecyclerView.Adapter implements View.OnClickListener{
private List list;
private Random random = new Random(System.currentTimeMillis());
public RecyclerViewAdapter(List list) {
this.list = list;
}
public OnItemOnClickListener getOnItemOnClickListener() {
return onItemOnClickListener;
}
public void setOnItemOnClickListener(OnItemOnClickListener onItemOnClickListener) {
this.onItemOnClickListener = onItemOnClickListener;
}
private OnItemOnClickListener onItemOnClickListener;
public interface OnItemOnClickListener{
void onItemClick(View view, int position);
}
@Override
public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Item8MvvmBinding item8MvvmBinding = DataBindingUtil.inflate(LayoutInflater.from(parent.getContext()), R.layout.item8_mvvm,parent,false);
item8MvvmBinding.getRoot().setOnClickListener(this);
return new RecyclerViewHolder(item8MvvmBinding);
}
@Override
public void onBindViewHolder(RecyclerViewHolder holder, int position) {
Item8MvvmBinding item8MvvmBinding = holder.getItem8MvvmBinding();
UserObservableBean userObservableBean = list.get(position);
item8MvvmBinding.setVariable(com.zhangqie.databinding.BR.userObserBean,userObservableBean);
//将position保存在itemView的Tag中，以便点击时进行获取
item8MvvmBinding.getRoot().setTag(position);
item8MvvmBinding.btnUpdate.setOnClickListener(new OnBtnClickListener(1, userObservableBean));
item8MvvmBinding.btnDelete.setOnClickListener(new OnBtnClickListener(2, position));
// 立刻执行绑定
item8MvvmBinding.executePendingBindings();
}
@Override
public int getItemCount() {
return list.size();
}
public void addData(UserObservableBean userObservableBean){
int position = random.nextInt(list.size()+1);
list.add(position,userObservableBean);
notifyItemInserted(position);//添加操作的动画
}
public void deleteData(int positionn){
if (list.size() == 0){
return;
}
int position = random.nextInt(list.size());
list.remove(position);
notifyItemRemoved(position);//删除操作的动画
}
@Override
public void onClick(View view) {
if (onItemOnClickListener != null)
onItemOnClickListener.onItemClick(view, (int) view.getTag());
}
private class OnBtnClickListener implements View.OnClickListener{
private int stats;//1,修改；2，删除
private UserObservableBean userBean;
private int position;
OnBtnClickListener(int stats, UserObservableBean userBean) {
this.stats = stats;
this.userBean = userBean;
}
OnBtnClickListener(int stats, int position) {
this.stats = stats;
this.position = position;
}
@Override
public void onClick(View v) {
switch (stats) {
case 1:
userBean.userName.set("修改后的名字");
break;
case 2:
list.remove(position);
notifyDataSetChanged();
break;
}
}
}
} 主Activity：
public class Demo8 extends AppCompatActivity {
Demo8Binding demo8Binding;
RecyclerViewAdapter recyclerViewAdapter;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
demo8Binding = DataBindingUtil.setContentView(this, R.layout.demo8);
initView();
}
private void initView(){
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this);
demo8Binding.demo8Recyclerview.setLayoutManager(layoutManager);
recyclerViewAdapter = new RecyclerViewAdapter(initObservableData());
demo8Binding.demo8Recyclerview.setAdapter(recyclerViewAdapter);
//item的点击事件
recyclerViewAdapter.setOnItemOnClickListener(new RecyclerViewAdapter.OnItemOnClickListener() {
@Override
public void onItemClick(View view, int position) {
Toast.makeText(Demo8.this, "行数：" + position, Toast.LENGTH_LONG).show();
}
});
demo8Binding.btnDemo8Add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
UserObservableBean userBean = new UserObservableBean();
userBean.userId.set(8);
userBean.userName.set("切切心语"+8);
userBean.userAge.set(25);
userBean.userSex.set(8 % 2 == 0 ? 1 : 0);
recyclerViewAdapter.addData(userBean);
}
});
demo8Binding.btnDemo8Refresh.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
recyclerViewAdapter.notifyDataSetChanged();
}
});
demo8Binding.btnDemo8Delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
recyclerViewAdapter.deleteData(1);
}
});
}
//初始化测试数据
private List initObservableData() {
List list = new ArrayList<>();
for (int i = 1; i < 6; i++) {
UserObservableBean userBean = new UserObservableBean();
userBean.userId.set(i);
userBean.userName.set("切切心语"+i);
userBean.userAge.set(18 + i);
userBean.userSex.set(i % 2 == 0 ? 1 : 0);
list.add(userBean);
}
return list;
}
} 自己练习的一个RecyclerView + Databinding使用
效果如图：
