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ListView是有addHeaderView和 addFooterView两个方法的.
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但是作为官方推荐的ListView的升级版RecyclerView缺无法实现这两个方法。
那么如果使用RecyclerView实现这两个方法的效果该怎么做呢?
网上查询了很久,试过各种各样的实现方式,终于让我发现一个还不错的实现方法,那么就给大家推荐一下。
项目地址(别人写的,非博主的)
我看了下这个源码,很简单,即写了一个继承RecyclerView的控件,自己实现addHeaderView和addFooterView两个方法
?
code
package com.xqx.com.recyclerviewheaderdemo;
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
import java.util.List;
public class XCRecyclerView extends RecyclerView{
private ArrayListView mHeaderViews = new ArrayList();
private ArrayListView mFooterViews = new ArrayList();
private RecyclerView.Adapter mAdapter;
private RecyclerView.Adapter mWrapAdapter;
private static final int TYPE_HEADER = -101;
private static final int TYPE_FOOTER = -102;
private static final int TYPE_LIST_ITEM = - 103;
public XCRecyclerView(Context context) {
this(context, null);
}
public XCRecyclerView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public XCRecyclerView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
private void init(Context context){
}
@Override
public void setAdapter(Adapter adapter) {
mAdapter = adapter;
mWrapAdapter = new WrapAdapter(mHeaderViews, mFooterViews, adapter);
super.setAdapter(mWrapAdapter);
mAdapter.registerAdapterDataObserver(mDataObserver);
}
public void addHeaderView(View view){
mHeaderViews.clear();
mHeaderViews.add(view);
}
public void addFooterView(View view){
mFooterViews.clear();
mFooterViews.add(view);
}
public int getHeaderViewsCount(){
return mHeaderViews.size();
}
public int getFooterViewsCount(){
return mFooterViews.size();
}
private final RecyclerView.AdapterDataObserver mDataObserver = new RecyclerView.AdapterDataObserver() {
@Override
public void onChanged() {
mWrapAdapter.notifyDataSetChanged();
}
@Override
public void onItemRangeChanged(int positionStart, int itemCount) {
mWrapAdapter.notifyItemRangeChanged(positionStart, itemCount);
}
// @Override
// public void onItemRangeChanged(int positionStart, int itemCount, Object payload) {
// mWrapAdapter.notifyItemRangeChanged(positionStart, itemCount, payload);
// }
@Override
public void onItemRangeInserted(int positionStart, int itemCount) {
mWrapAdapter.notifyItemRangeInserted(positionStart, itemCount);
}
@Override
public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
mWrapAdapter.notifyItemMoved(fromPosition, toPosition);
}
@Override
public void onItemRangeRemoved(int positionStart, int itemCount) {
mWrapAdapter.notifyItemRangeRemoved(positionStart, itemCount);
}
};
private class WrapAdapter extends RecyclerView.AdapterViewHolder{
private Adapter mAdapter;
private ListView mHeaderViews;
private ListView mFooterViews;
public WrapAdapter(ListView headerViews,ListView footerViews,Adapter adapter){
this.mAdapter = adapter;
this.mHeaderViews = headerViews;
this.mFooterViews = footerViews;
}
public int getHeaderCount(){
return this.mHeaderViews.size();
}
public int getFooterCount(){
return this.mFooterViews.size();
}
public boolean isHeader(int position){
return position = 0 position this.mHeaderViews.size();
}
public boolean isFooter(int position){
return position getItemCount() position = getItemCount() - this.mFooterViews.size();
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if(viewType == TYPE_HEADER){
return new CustomViewHolder(this.mHeaderViews.get(0));
}else if(viewType == TYPE_FOOTER){
return new CustomViewHolder(this.mFooterViews.get(0));
}else{
return this.mAdapter.onCreateViewHolder(parent,viewType);
}
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
if(isHeader(position)) return;
if(isFooter(position)) return;
int rePosition = position - getHeaderCount();
int itemCount = this.mAdapter.getItemCount();
if(this.mAdapter != null){
if(rePosition itemCount){
Log.v("czm","rePosition/itemCount="+rePosition+"/"+itemCount);
this.mAdapter.onBindViewHolder(holder,rePosition);
return;
}
}
}
@Override
public long getItemId(int position) {
if (this.mAdapter != null position = getHeaderCount()) {
int rePosition = position - getHeaderCount();
int itemCount = this.mAdapter.getItemCount();
if (rePosition itemCount) {
return this.mAdapter.getItemId(rePosition);
}
}
return -1;
}
@Override
public int getItemViewType(int position) {
if(isHeader(position)){
return TYPE_HEADER;
}
if(isFooter(position)){
return TYPE_FOOTER;
}
int rePosition = position - getHeaderCount();
int itemCount = this.mAdapter.getItemCount();
if(rePosition itemCount){
return this.mAdapter.getItemViewType(position);
}
return TYPE_LIST_ITEM;
}
@Override
public int getItemCount() {
if(this.mAdapter != null){
return getHeaderCount() + getFooterCount() + this.mAdapter.getItemCount();
}else{
return getHeaderCount() + getFooterCount();
}
}
@Override
public void registerAdapterDataObserver(AdapterDataObserver observer) {
if(this.mAdapter != null){
this.mAdapter.registerAdapterDataObserver(observer);
}
}
@Override
public void unregisterAdapterDataObserver(AdapterDataObserver observer) {
if(this.mAdapter != null){
this.mAdapter.unregisterAdapterDataObserver(observer);
}
}
private class CustomViewHolder extends ViewHolder{
public CustomViewHolder(View itemView) {
super(itemView);
}
}
}
}
XCRecyclerView
使用方法github里也写的清清楚楚的
?
code
private MyAdapter mAdapter;
private XCRecyclerView mRecyclerView;
private ListString mData;
private View mHeaderView;
private View mFooterView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mData = new ArrayListString();
for(int i = 0; i 10 ;i++){
mData.add("item_" + i);
}
mAdapter = new MyAdapter(mData);
mRecyclerView = (XCRecyclerView) findViewById(R.id.recycler_view);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
mHeaderView = LayoutInflater.from(this).inflate(R.layout.layout_header,mRecyclerView,false);
mFooterView = LayoutInflater.from(this).inflate(R.layout.layout_footer,mRecyclerView,false);
mRecyclerView.addHeaderView(mHeaderView);
mRecyclerView.addFooterView(mFooterView);
mRecyclerView.setAdapter(mAdapter);
}
注意点:
addHeaderView之后 列表的数据坐标即相应发生变化!即addHeadView一次,列表第一个数据的下坐标+1(0--1)
1.目标组件(button)有两套,放在顶部和内容中间;
2.当内容中间的组件滑动至顶部栏位置时控制显示/隐藏顶部和中间的组件(涉及到组件获取在屏幕的位置知识点);
activity代码:
public class MainActivity extends AppCompatActivity implements ObservableScrollView.ScrollViewListener {
private ObservableScrollView scrollView;
private Button topBtn1, topBtn2, middleBtn1, middleBtn2;
private View topPanel, middlePanel;
private int topHeight;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initViews();
initListeners();
第一种:点击File - Settings - Editor - File and Code Templates
第二种:点击File - Settings - Editor - Live Template
这样当新建一个类或者方法后,在类或方法名上面输入缩写(cc或cm),就会有提示是否添加类注释。
Shift+Alt+G 添加注释 Shift+Alt+Z 取消注释
方法一:在AndroidManifest.xml中
application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@android:style/Theme.NoTitleBar"
添加theme属性为NoTitleBar就可以了。
方法二:在MainActivity.java中
@Override
public void onCreate (Bundle savedInstanceState) {
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
把requestWindowFeature()方法添加在setContentView()方法之前,这个方法只是把标题隐藏了。
一头叫USB一头叫TYPEC。普通安卓接口就叫做安卓接口也叫做USB连接线,安卓头指的是手机安卓系统的充电插头的意思。手机充电器大致可以分为旅行充电器、座式充电器和维护型充电器,一般用户接触的主要是前面两种。而市场上卖得最多的是旅行充电器。
安卓充电功率
手机常用锂离子电池的充电器采用的是恒流限压充电制,充电电流一般采用C2左右即采用两小时充电率,比如500mAh电池采用250mA充电大约两小时达到42V后再恒压充电。
lion电池并不适合采用NIMH电池高级快速充电器所用的-DV/DT检测快速充电方式,因为lion电池对充电电流有严格的限制.锂离子非常活泼,大电流充电很容易产生危险。