为什么 CardView 导致滚动过程变慢？
why CardView causing slow down the scrolling process?
I was using listView without with the custom layout which is having
Linear layout as parent layout. Scrolling was fine, Then I need to
implement CardView for elevation and round corner, After implementation
list Scrolling become slow.Moreover it is also slowing down the
RecyclerView Process.
here is my xml.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/WhiteSmoke"
android:layout_margin="5dp"
android:orientation="vertical">
<android.support.v7.widget.CardView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
card_view:cardCornerRadius="12dp"
card_view:cardElevation="6dp">
<LinearLayout
android:id="@+id/layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@drawable/listviewback"
android:orientation="vertical"
android:padding="5dip">
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView
android:id="@+id/custom_listviewIV"
android:layout_width="40dip"
android:layout_height="40dip"
android:layout_marginLeft="5dip"
android:layout_marginRight="5dip"
android:src="@drawable/avatar2"
/>
<TextView
android:id="@+id/custom_listviewMainTv"
android:layout_width="180dip"
android:layout_height="45dip"
android:layout_marginLeft="2dip"
android:layout_toLeftOf="@+id/custom_listviewLinearLay"
android:layout_toRightOf="@+id/custom_listviewIV"
android:maxLines="2"
android:paddingTop="2dip"
android:text="Goverment "
android:textColor="@color/GreyDark"
android:textSize="15sp"
android:textStyle="bold"/>
<LinearLayout
android:id="@+id/custom_listviewLinearLay"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_margin="2dip"
android:orientation="vertical">
<TextView
android:id="@+id/custom_listviewRating"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_gravity="right"
android:layout_marginBottom="2dp"
android:background="@drawable/tv_round"
android:backgroundTint="@color/primary_dark"
android:gravity="center"
android:text="4.2/5"
android:textColor="@color/white"
android:textSize="13sp" />
</LinearLayout>
</RelativeLayout>
<View
android:layout_width="match_parent"
android:layout_height="1dip"
android:layout_marginLeft="5dip"
android:background="@color/GreyLight" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="2dip"
android:orientation="vertical"
android:paddingLeft="10dip"
android:paddingTop="1dip"
android:paddingRight="10dip"
>
<TextView
android:id="@+id/custom_listviewFirstTv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="3dip"
android:text="Fsc Pre Engineering1"
android:textColor="@color/greyligher"
android:textSize="13sp"
android:visibility="gone" />
<TextView
android:id="@+id/custom_listviewSecondTv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Fsc Pre Engineering2"
android:textColor="@color/greyligher"
android:textSize="13sp"
android:visibility="gone" />
<TextView
android:id="@+id/custom_listviewThirdTv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Fsc Pre Engineering3"
android:textColor="@color/greyligher"
android:textSize="13sp"
android:visibility="gone" />
<TextView
android:id="@+id/custom_listviewFourthTv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="more+"
android:textColor="@color/black"
android:textSize="13sp"
android:visibility="gone" />
</LinearLayout>
</LinearLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
here is my adapter code
public class CustomAdaptor extends BaseAdapter {
private ArrayList<Data> myDataList;
private Context context;
LinearLayout linearLayout;
public CustomAdaptor(ArrayList<Data> mylist, Context context) {
this.myDataList = mylist;
this.context = context;
}
public int getCount() {
return myDataList.size();
}
public Object getItem(int position) {
return myDataList.get(position);
}
public long getItemId(int position) {
return position;
}
public View getView(final int position, View convertView, ViewGroup parent) {
View view = View.inflate(context, R.layout.custom_listview, null);
linearLayout= view.findViewById(R.id.layout);
TextView collegeName = view.findViewById(R.id.custom_listviewMainTv);
TextView rating = view.findViewById(R.id.custom_listviewRating);
ImageView country = view.findViewById(R.id.custom_listviewIV);
LinearLayout ll= view.findViewById(R.id.custom_listviewLinearLay);
TextView firstTv= view.findViewById(R.id.custom_listviewFirstTv);
TextView secondTv= view.findViewById(R.id.custom_listviewSecondTv);
TextView thirdTv= view.findViewById(R.id.custom_listviewThirdTv);
TextView fourthTv= view.findViewById(R.id.custom_listviewFourthTv);
collegeName.setText(myDataList.get(position).getName());
rating.setText("" + myDataList.get(position).getRating());
Double n=0.0;
if (n==myDataList.get(position).getRating()) {
ll.setVisibility(View.GONE);
}
if(!myDataList.get(position).getCourseList().isEmpty()) {
if (!myDataList.get(position).getCourseList().get(0).lst.get(0).getCourseName().equals("")) {
firstTv.setVisibility(View.VISIBLE);
firstTv.setText(myDataList.get(position).getCourseList().get(0).lst.get(0).getCourseName());
}
if (myDataList.get(position).getCourseList().get(0).lst.size()>1) {
if (!myDataList.get(position).getCourseList().get(0).lst.get(1).getCourseName().equals("")) {
secondTv.setVisibility(View.VISIBLE);
secondTv.setText(myDataList.get(position).getCourseList().get(0).lst.get(1).getCourseName());
}
}
if (myDataList.get(position).getCourseList().get(0).lst.size()>2) {
if (!myDataList.get(position).getCourseList().get(0).lst.get(2).getCourseName().equals("")) {
thirdTv.setVisibility(View.VISIBLE);
thirdTv.setText(myDataList.get(position).getCourseList().get(0).lst.get(2).getCourseName());
}
}
if (myDataList.get(position).getCourseList().size()>1) {
fourthTv.setVisibility(View.VISIBLE);
fourthTv.setText("+More");
}else if(myDataList.get(position).getCourseList().get(0).lst.size()>3) {
fourthTv.setVisibility(View.VISIBLE);
fourthTv.setText("+More");
}
String img = "" + myDataList.get(position).getImage();
img = img.replaceAll(" ", "%20");
Glide.with(context).load(img).into(country);
view.setTag(myDataList.get(position).getId());
}
else {
linearLayout.setVisibility(View.GONE);
}
return view;
}
}
尽量减少视图层次结构并减少绑定的复杂操作。
Cardview 可能只是 "breaking point" 可以以未优化的方式使用多少图形内容而不会滞后。正如一些评论中提到的，您应该使用 ViewHolder，这是一个使用 viewholder 的简单示例：
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.list_entry, null);
holder = new ViewHolder();
holder.nameTextView = (TextView) convertView.findViewById(R.id.person_name);
holder.surnameTextView = (TextView) convertView.findViewById(R.id.person_surname);
holder.personImageView = (ImageView) convertView.findViewById(R.id.person_image);
convertView.setTag(holder);
}
else {
holder = (ViewHolder) convertView.getTag();
}
Person person = getItem(position);
holder.nameTextView.setText(person.getName());
holder.surnameTextView.setText(person.getSurname());
//holder.personImageView.setImageBitmap(person.getImage());
return convertView;
}
你可以阅读更多相关内容here
此外，您应该使用 RecyclerView 而不是 ListView 来优化性能。
I was using listView without with the custom layout which is having Linear layout as parent layout. Scrolling was fine, Then I need to implement CardView for elevation and round corner, After implementation list Scrolling become slow.Moreover it is also slowing down the RecyclerView Process. here is my xml.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/WhiteSmoke"
android:layout_margin="5dp"
android:orientation="vertical">
<android.support.v7.widget.CardView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
card_view:cardCornerRadius="12dp"
card_view:cardElevation="6dp">
<LinearLayout
android:id="@+id/layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@drawable/listviewback"
android:orientation="vertical"
android:padding="5dip">
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView
android:id="@+id/custom_listviewIV"
android:layout_width="40dip"
android:layout_height="40dip"
android:layout_marginLeft="5dip"
android:layout_marginRight="5dip"
android:src="@drawable/avatar2"
/>
<TextView
android:id="@+id/custom_listviewMainTv"
android:layout_width="180dip"
android:layout_height="45dip"
android:layout_marginLeft="2dip"
android:layout_toLeftOf="@+id/custom_listviewLinearLay"
android:layout_toRightOf="@+id/custom_listviewIV"
android:maxLines="2"
android:paddingTop="2dip"
android:text="Goverment "
android:textColor="@color/GreyDark"
android:textSize="15sp"
android:textStyle="bold"/>
<LinearLayout
android:id="@+id/custom_listviewLinearLay"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_margin="2dip"
android:orientation="vertical">
<TextView
android:id="@+id/custom_listviewRating"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_gravity="right"
android:layout_marginBottom="2dp"
android:background="@drawable/tv_round"
android:backgroundTint="@color/primary_dark"
android:gravity="center"
android:text="4.2/5"
android:textColor="@color/white"
android:textSize="13sp" />
</LinearLayout>
</RelativeLayout>
<View
android:layout_width="match_parent"
android:layout_height="1dip"
android:layout_marginLeft="5dip"
android:background="@color/GreyLight" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="2dip"
android:orientation="vertical"
android:paddingLeft="10dip"
android:paddingTop="1dip"
android:paddingRight="10dip"
>
<TextView
android:id="@+id/custom_listviewFirstTv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="3dip"
android:text="Fsc Pre Engineering1"
android:textColor="@color/greyligher"
android:textSize="13sp"
android:visibility="gone" />
<TextView
android:id="@+id/custom_listviewSecondTv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Fsc Pre Engineering2"
android:textColor="@color/greyligher"
android:textSize="13sp"
android:visibility="gone" />
<TextView
android:id="@+id/custom_listviewThirdTv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Fsc Pre Engineering3"
android:textColor="@color/greyligher"
android:textSize="13sp"
android:visibility="gone" />
<TextView
android:id="@+id/custom_listviewFourthTv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="more+"
android:textColor="@color/black"
android:textSize="13sp"
android:visibility="gone" />
</LinearLayout>
</LinearLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
here is my adapter code
public class CustomAdaptor extends BaseAdapter {
private ArrayList<Data> myDataList;
private Context context;
LinearLayout linearLayout;
public CustomAdaptor(ArrayList<Data> mylist, Context context) {
this.myDataList = mylist;
this.context = context;
}
public int getCount() {
return myDataList.size();
}
public Object getItem(int position) {
return myDataList.get(position);
}
public long getItemId(int position) {
return position;
}
public View getView(final int position, View convertView, ViewGroup parent) {
View view = View.inflate(context, R.layout.custom_listview, null);
linearLayout= view.findViewById(R.id.layout);
TextView collegeName = view.findViewById(R.id.custom_listviewMainTv);
TextView rating = view.findViewById(R.id.custom_listviewRating);
ImageView country = view.findViewById(R.id.custom_listviewIV);
LinearLayout ll= view.findViewById(R.id.custom_listviewLinearLay);
TextView firstTv= view.findViewById(R.id.custom_listviewFirstTv);
TextView secondTv= view.findViewById(R.id.custom_listviewSecondTv);
TextView thirdTv= view.findViewById(R.id.custom_listviewThirdTv);
TextView fourthTv= view.findViewById(R.id.custom_listviewFourthTv);
collegeName.setText(myDataList.get(position).getName());
rating.setText("" + myDataList.get(position).getRating());
Double n=0.0;
if (n==myDataList.get(position).getRating()) {
ll.setVisibility(View.GONE);
}
if(!myDataList.get(position).getCourseList().isEmpty()) {
if (!myDataList.get(position).getCourseList().get(0).lst.get(0).getCourseName().equals("")) {
firstTv.setVisibility(View.VISIBLE);
firstTv.setText(myDataList.get(position).getCourseList().get(0).lst.get(0).getCourseName());
}
if (myDataList.get(position).getCourseList().get(0).lst.size()>1) {
if (!myDataList.get(position).getCourseList().get(0).lst.get(1).getCourseName().equals("")) {
secondTv.setVisibility(View.VISIBLE);
secondTv.setText(myDataList.get(position).getCourseList().get(0).lst.get(1).getCourseName());
}
}
if (myDataList.get(position).getCourseList().get(0).lst.size()>2) {
if (!myDataList.get(position).getCourseList().get(0).lst.get(2).getCourseName().equals("")) {
thirdTv.setVisibility(View.VISIBLE);
thirdTv.setText(myDataList.get(position).getCourseList().get(0).lst.get(2).getCourseName());
}
}
if (myDataList.get(position).getCourseList().size()>1) {
fourthTv.setVisibility(View.VISIBLE);
fourthTv.setText("+More");
}else if(myDataList.get(position).getCourseList().get(0).lst.size()>3) {
fourthTv.setVisibility(View.VISIBLE);
fourthTv.setText("+More");
}
String img = "" + myDataList.get(position).getImage();
img = img.replaceAll(" ", "%20");
Glide.with(context).load(img).into(country);
view.setTag(myDataList.get(position).getId());
}
else {
linearLayout.setVisibility(View.GONE);
}
return view;
}
}
尽量减少视图层次结构并减少绑定的复杂操作。
Cardview 可能只是 "breaking point" 可以以未优化的方式使用多少图形内容而不会滞后。正如一些评论中提到的，您应该使用 ViewHolder，这是一个使用 viewholder 的简单示例：
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.list_entry, null);
holder = new ViewHolder();
holder.nameTextView = (TextView) convertView.findViewById(R.id.person_name);
holder.surnameTextView = (TextView) convertView.findViewById(R.id.person_surname);
holder.personImageView = (ImageView) convertView.findViewById(R.id.person_image);
convertView.setTag(holder);
}
else {
holder = (ViewHolder) convertView.getTag();
}
Person person = getItem(position);
holder.nameTextView.setText(person.getName());
holder.surnameTextView.setText(person.getSurname());
//holder.personImageView.setImageBitmap(person.getImage());
return convertView;
}
你可以阅读更多相关内容here
此外，您应该使用 RecyclerView 而不是 ListView 来优化性能。