写此博客目的仅仅用于帮助自己做笔记
吸顶效果在很多APP都可以看见，现在可以借助RecyclerView的ItemDecoration 来简单实现一个吸顶效果直接上效果图：
- 首先实现一个Model实体，该Model需要包含区分不同组的字段，例如下面这个实体用来区分的便是mTitle字段，当然这个字段是随便取什么的，只要定好就可以。
public class Model {
private String mTitle;
private String mContent;
private int mRsId;
public Model(String title, String content, int rsId) {
mTitle = title;
mContent = content;
mRsId = rsId;
}
public String getTitle() {
return mTitle;
}
public void setTitle(String title) {
mTitle = title;
}
public String getContent() {
return mContent;
}
public void setContent(String content) {
mContent = content;
}
public int getRsId() {
return mRsId;
}
public void setRsId(int rsId) {
mRsId = rsId;
}
}
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创建一个RecyclerView并且实现实现适配器，先实现如下效果：
适配器代码如下：
public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
private List<Model> mModelList;
private LayoutInflater mInflater;
public Adapter(Context context) {
mInflater = LayoutInflater.from(context);
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.item_l, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Model model = mModelList.get(position);
holder.mTextView.setText(model.getContent());
holder.mImageView.setImageResource(model.getRsId());
}
@Override
public int getItemCount() {
return mModelList.size();
}
static class ViewHolder extends RecyclerView.ViewHolder {
private TextView mTextView;
private ImageView mImageView;
public ViewHolder(View itemView) {
super(itemView);
mTextView = itemView.findViewById(R.id.txt);
mImageView = itemView.findViewById(R.id.img);
}
}
}
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编写一个接口用来对数据判断
public interface ISticky {
//判断是否为同类别的第一个位置
boolean isFirstPosition(int pos);
//获取标题
String getGroupTitle(int pos);
}
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- 最重要的一步来了 就是自定义ItemDecoration，代码如下，详细注释我已经写在里面了
public class StickyItemDecoration extends RecyclerView.ItemDecoration {
private ISticky mISticky;
//矩形高度
private int mRectHeight;
//文字TextSize
private int mTextPaintSize;
private Paint mTxtPaint;
private Paint mRectPaint;
//分割线画笔
private Paint mDividerPaint;
public StickyItemDecoration(Context context,ISticky iSticky) {
mISticky=iSticky;
mRectHeight= (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,30,
context.getResources().getDisplayMetrics());
mTextPaintSize=(int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,17,
context.getResources().getDisplayMetrics());
mTxtPaint=new Paint(Paint.ANTI_ALIAS_FLAG);
mTxtPaint.setColor(Color.BLACK);
mTxtPaint.setTextSize(mTextPaintSize);
mRectPaint=new Paint(Paint.ANTI_ALIAS_FLAG);
mRectPaint.setStyle(Paint.Style.FILL);
mRectPaint.setColor(Color.parseColor("#DDDDDD"));
mDividerPaint=new Paint(Paint.ANTI_ALIAS_FLAG);
mDividerPaint.setStyle(Paint.Style.FILL);
mDividerPaint.setColor(Color.WHITE);
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
super.onDraw(c, parent, state);
int childCount=parent.getChildCount();
for (int i = 0; i < childCount; i++) {
View view=parent.getChildAt(i);
int left=parent.getPaddingLeft();
int right=parent.getWidth()-parent.getPaddingRight();
int top=view.getTop()-1;
int bottom=view.getTop();
//Item分割线
c.drawRect(left,top,right,bottom,mDividerPaint);
}
}
@Override
public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
super.onDrawOver(c, parent, state);
int childCount=parent.getChildCount();
int itemCount=state.getItemCount();
int left=parent.getPaddingLeft();
int right=parent.getWidth()-parent.getPaddingRight();
String preGroupTitle;
String groupTitle="";
for (int i = 0; i < childCount; i++) {
View child=parent.getChildAt(i);
int pos=parent.getChildLayoutPosition(child);
preGroupTitle=groupTitle;
groupTitle=mISticky.getGroupTitle(pos);
//如果当前分组名和之前分组名一样，忽略此次循环
if (groupTitle.equals(preGroupTitle)) {
continue;
}
//文字的基线，保证显示完全
int textBaseLine=Math.max(mRectHeight,child.getTop());
//分组标题
String title=mISticky.getGroupTitle(pos);
int viewBottom=child.getBottom();
//加入限定 防止数组越界
if (pos + 1 < itemCount) {
String nextGroupTitle=mISticky.getGroupTitle(pos+1);
//当分组不一样 并且改组要向上移动时候
if (!nextGroupTitle.equals(groupTitle) && viewBottom < textBaseLine) {
//将上一个往上移动
textBaseLine = viewBottom;
}
}
//绘制边框
c.drawRect(left, textBaseLine - mRectHeight, right, textBaseLine, mRectPaint);
//绘制文字并且实现文字居中
int value= (int) Math.abs(mTxtPaint.getFontMetrics().descent
+mTxtPaint.getFontMetrics().ascent);
c.drawText(title, left,
textBaseLine-(mRectHeight+value)/2,
mTxtPaint);
}
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
int pos=parent.getChildLayoutPosition(view);
if (mISticky.isFirstPosition(pos)) {
outRect.top=mRectHeight;
outRect.bottom=1;
}else {
outRect.bottom=1;
}
}
}
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5.最后只要设置一下即可
final List<Model> modelList=new ArrayList<>();
for (int i = 0; i < 10; i++) {
modelList.add(new Model("标题1","Content:1_"+i,R.mipmap.ic_launcher_round));
}
for (int i = 0; i < 10; i++) {
modelList.add(new Model("标题2","Content:2_"+i,R.mipmap.ic_launcher_round));
}
for (int i = 0; i < 10; i++) {
modelList.add(new Model("标题3","Content:3_"+i,R.mipmap.ic_launcher_round));
}
mRecyclerView.addItemDecoration(new StickyItemDecoration(this, new ISticky() {
@Override
public boolean isFirstPosition(int pos) {
return pos==0||
!modelList.get(pos).getTitle().equals(modelList.get(pos-1).getTitle());
}
@Override
public String getGroupTitle(int pos) {
return modelList.get(pos).getTitle();
}
}));
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备注：第一次写博客 如有不好之处 还望大家见谅
转自:https://blog.csdn.net/qq_34240569/article/details/78283447
写此博客目的仅仅用于帮助自己做笔记
吸顶效果在很多APP都可以看见，现在可以借助RecyclerView的ItemDecoration 来简单实现一个吸顶效果直接上效果图：
- 首先实现一个Model实体，该Model需要包含区分不同组的字段，例如下面这个实体用来区分的便是mTitle字段，当然这个字段是随便取什么的，只要定好就可以。
public class Model {
private String mTitle;
private String mContent;
private int mRsId;
public Model(String title, String content, int rsId) {
mTitle = title;
mContent = content;
mRsId = rsId;
}
public String getTitle() {
return mTitle;
}
public void setTitle(String title) {
mTitle = title;
}
public String getContent() {
return mContent;
}
public void setContent(String content) {
mContent = content;
}
public int getRsId() {
return mRsId;
}
public void setRsId(int rsId) {
mRsId = rsId;
}
}
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- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
创建一个RecyclerView并且实现实现适配器，先实现如下效果：
适配器代码如下：
public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
private List<Model> mModelList;
private LayoutInflater mInflater;
public Adapter(Context context) {
mInflater = LayoutInflater.from(context);
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.item_l, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Model model = mModelList.get(position);
holder.mTextView.setText(model.getContent());
holder.mImageView.setImageResource(model.getRsId());
}
@Override
public int getItemCount() {
return mModelList.size();
}
static class ViewHolder extends RecyclerView.ViewHolder {
private TextView mTextView;
private ImageView mImageView;
public ViewHolder(View itemView) {
super(itemView);
mTextView = itemView.findViewById(R.id.txt);
mImageView = itemView.findViewById(R.id.img);
}
}
}
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- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
编写一个接口用来对数据判断
public interface ISticky {
//判断是否为同类别的第一个位置
boolean isFirstPosition(int pos);
//获取标题
String getGroupTitle(int pos);
}
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- 最重要的一步来了 就是自定义ItemDecoration，代码如下，详细注释我已经写在里面了
public class StickyItemDecoration extends RecyclerView.ItemDecoration {
private ISticky mISticky;
//矩形高度
private int mRectHeight;
//文字TextSize
private int mTextPaintSize;
private Paint mTxtPaint;
private Paint mRectPaint;
//分割线画笔
private Paint mDividerPaint;
public StickyItemDecoration(Context context,ISticky iSticky) {
mISticky=iSticky;
mRectHeight= (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,30,
context.getResources().getDisplayMetrics());
mTextPaintSize=(int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,17,
context.getResources().getDisplayMetrics());
mTxtPaint=new Paint(Paint.ANTI_ALIAS_FLAG);
mTxtPaint.setColor(Color.BLACK);
mTxtPaint.setTextSize(mTextPaintSize);
mRectPaint=new Paint(Paint.ANTI_ALIAS_FLAG);
mRectPaint.setStyle(Paint.Style.FILL);
mRectPaint.setColor(Color.parseColor("#DDDDDD"));
mDividerPaint=new Paint(Paint.ANTI_ALIAS_FLAG);
mDividerPaint.setStyle(Paint.Style.FILL);
mDividerPaint.setColor(Color.WHITE);
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
super.onDraw(c, parent, state);
int childCount=parent.getChildCount();
for (int i = 0; i < childCount; i++) {
View view=parent.getChildAt(i);
int left=parent.getPaddingLeft();
int right=parent.getWidth()-parent.getPaddingRight();
int top=view.getTop()-1;
int bottom=view.getTop();
//Item分割线
c.drawRect(left,top,right,bottom,mDividerPaint);
}
}
@Override
public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
super.onDrawOver(c, parent, state);
int childCount=parent.getChildCount();
int itemCount=state.getItemCount();
int left=parent.getPaddingLeft();
int right=parent.getWidth()-parent.getPaddingRight();
String preGroupTitle;
String groupTitle="";
for (int i = 0; i < childCount; i++) {
View child=parent.getChildAt(i);
int pos=parent.getChildLayoutPosition(child);
preGroupTitle=groupTitle;
groupTitle=mISticky.getGroupTitle(pos);
//如果当前分组名和之前分组名一样，忽略此次循环
if (groupTitle.equals(preGroupTitle)) {
continue;
}
//文字的基线，保证显示完全
int textBaseLine=Math.max(mRectHeight,child.getTop());
//分组标题
String title=mISticky.getGroupTitle(pos);
int viewBottom=child.getBottom();
//加入限定 防止数组越界
if (pos + 1 < itemCount) {
String nextGroupTitle=mISticky.getGroupTitle(pos+1);
//当分组不一样 并且改组要向上移动时候
if (!nextGroupTitle.equals(groupTitle) && viewBottom < textBaseLine) {
//将上一个往上移动
textBaseLine = viewBottom;
}
}
//绘制边框
c.drawRect(left, textBaseLine - mRectHeight, right, textBaseLine, mRectPaint);
//绘制文字并且实现文字居中
int value= (int) Math.abs(mTxtPaint.getFontMetrics().descent
+mTxtPaint.getFontMetrics().ascent);
c.drawText(title, left,
textBaseLine-(mRectHeight+value)/2,
mTxtPaint);
}
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
int pos=parent.getChildLayoutPosition(view);
if (mISticky.isFirstPosition(pos)) {
outRect.top=mRectHeight;
outRect.bottom=1;
}else {
outRect.bottom=1;
}
}
}
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5.最后只要设置一下即可
final List<Model> modelList=new ArrayList<>();
for (int i = 0; i < 10; i++) {
modelList.add(new Model("标题1","Content:1_"+i,R.mipmap.ic_launcher_round));
}
for (int i = 0; i < 10; i++) {
modelList.add(new Model("标题2","Content:2_"+i,R.mipmap.ic_launcher_round));
}
for (int i = 0; i < 10; i++) {
modelList.add(new Model("标题3","Content:3_"+i,R.mipmap.ic_launcher_round));
}
mRecyclerView.addItemDecoration(new StickyItemDecoration(this, new ISticky() {
@Override
public boolean isFirstPosition(int pos) {
return pos==0||
!modelList.get(pos).getTitle().equals(modelList.get(pos-1).getTitle());
}
@Override
public String getGroupTitle(int pos) {
return modelList.get(pos).getTitle();
}
}));
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备注：第一次写博客 如有不好之处 还望大家见谅