[android-developers] Re: Reusing Views in Custom Adapter
What exactly is the problem. Bonkers doesn't really tell us much.
On Nov 29, 8:12 pm, authorwjf wfran...@softlayer.com wrote:
Hi Android Framework Gurus!
I am hoping someone out there can answer a question for me about re-
using views in my adapters. My understanding, is that for performance
reasons this is something I should always always always do. Yet in my
experience, doing so always results in the view, whether a grid or
list, going wonky once I get very many children in the view. I
suspect, I'm just doing something flat out wrong. So I put together a
simple straight-forward project to demonstrate both how I attempt to
re-use the views in a grid view, and how it goes bonkers if you add a
few hundred entries and scroll the list. I've tested on both the
cupcake emulator as well as my gingerbread device with the same
results.
Thanks in advance to anyone who takes the time to respond!
==Layouts==
main.xml
?xml version=1.0 encoding=utf-8?
LinearLayout xmlns:android=http://schemas.android.com/apk/res/
android
android:layout_width=fill_parent
android:layout_height=fill_parent
android:orientation=vertical
TextView
android:layout_width=fill_parent
android:layout_height=wrap_content
android:text=Reuse Views Demo /
GridView
android:id=@+id/gridview
android:layout_width=fill_parent
android:layout_height=fill_parent
android:padding=5dp
android:verticalSpacing=5dp
android:horizontalSpacing=10dp
android:numColumns=auto_fit
android:columnWidth=60dp
android:stretchMode=columnWidth
android:gravity=center_horizontal/
/LinearLayout
grid_item.xml
LinearLayout xmlns:android=http://schemas.android.com/apk/res/
android
android:id=@+id/GridItem
android:layout_width=fill_parent
android:layout_height=wrap_content
android:orientation=vertical
android:gravity=center_horizontal
TextView android:id=@+id/grid_item_text
android:layout_width=wrap_content
android:layout_height=wrap_content
android:gravity=center_horizontal
android:layout_marginBottom=4dip/
/LinearLayout
==source==
Main.java
package com.authorwjf.reuseviews;
import java.util.ArrayList;
import android.app.Activity;
import android.os.Bundle;
import android.widget.GridView;
public class Main extends Activity {
private CustomAdapter mAdapter;
private ArrayListString mItems = new ArrayListString();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
for (int i = 0; i200; i++) {
mItems.add(Integer.toString(i));
}
mAdapter = new CustomAdapter(this, mItems);
GridView g = (GridView) findViewById(R.id.gridview);
g.setAdapter(mAdapter);
}
}
CustomAdapter.java
package com.authorwjf.reuseviews;
import java.util.ArrayList;
import com.authorwjf.reuseviews.R;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class CustomAdapter extends BaseAdapter {
private Context mContext;
private ArrayListString mItems;
public CustomAdapter(Context c, ArrayListString items) {
mContext = c;
mItems = items;
}
@Override
public int getCount() {
return mItems.size();
}
@Override
public Object getItem(int position) {
return mItems.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
View v = convertView;
if (v == null) {
LayoutInflater li = (LayoutInflater)
mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = li.inflate(R.layout.grid_item, null);
TextView tv = (TextView)v.findViewById(R.id.grid_item_text);
tv.setText(Item #+mItems.get(position));
}
return v;
}
}
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Re: [android-developers] Re: Reusing Views in Custom Adapter
You should always set the whole content of the layout in getView(). When
v is not null right now you are returning that view without setting your
text.
Something like this:
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater li = (LayoutInflater)
mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = li.inflate(R.layout.grid_item, null);
}
TextView tv = (TextView)v.findViewById(R.id.grid_item_text);
tv.setText(Item #+mItems.get(position));
return v;
}
On Tue, Nov 29, 2011 at 5:17 PM, Kumar Bibek coomar@gmail.com wrote:
What exactly is the problem. Bonkers doesn't really tell us much.
On Nov 29, 8:12 pm, authorwjf wfran...@softlayer.com wrote:
Hi Android Framework Gurus!
I am hoping someone out there can answer a question for me about re-
using views in my adapters. My understanding, is that for performance
reasons this is something I should always always always do. Yet in my
experience, doing so always results in the view, whether a grid or
list, going wonky once I get very many children in the view. I
suspect, I'm just doing something flat out wrong. So I put together a
simple straight-forward project to demonstrate both how I attempt to
re-use the views in a grid view, and how it goes bonkers if you add a
few hundred entries and scroll the list. I've tested on both the
cupcake emulator as well as my gingerbread device with the same
results.
Thanks in advance to anyone who takes the time to respond!
==Layouts==
main.xml
?xml version=1.0 encoding=utf-8?
LinearLayout xmlns:android=http://schemas.android.com/apk/res/
android
android:layout_width=fill_parent
android:layout_height=fill_parent
android:orientation=vertical
TextView
android:layout_width=fill_parent
android:layout_height=wrap_content
android:text=Reuse Views Demo /
GridView
android:id=@+id/gridview
android:layout_width=fill_parent
android:layout_height=fill_parent
android:padding=5dp
android:verticalSpacing=5dp
android:horizontalSpacing=10dp
android:numColumns=auto_fit
android:columnWidth=60dp
android:stretchMode=columnWidth
android:gravity=center_horizontal/
/LinearLayout
grid_item.xml
LinearLayout xmlns:android=http://schemas.android.com/apk/res/
android
android:id=@+id/GridItem
android:layout_width=fill_parent
android:layout_height=wrap_content
android:orientation=vertical
android:gravity=center_horizontal
TextView android:id=@+id/grid_item_text
android:layout_width=wrap_content
android:layout_height=wrap_content
android:gravity=center_horizontal
android:layout_marginBottom=4dip/
/LinearLayout
==source==
Main.java
package com.authorwjf.reuseviews;
import java.util.ArrayList;
import android.app.Activity;
import android.os.Bundle;
import android.widget.GridView;
public class Main extends Activity {
private CustomAdapter mAdapter;
private ArrayListString mItems = new ArrayListString();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
for (int i = 0; i200; i++) {
mItems.add(Integer.toString(i));
}
mAdapter = new CustomAdapter(this, mItems);
GridView g = (GridView) findViewById(R.id.gridview);
g.setAdapter(mAdapter);
}
}
CustomAdapter.java
package com.authorwjf.reuseviews;
import java.util.ArrayList;
import com.authorwjf.reuseviews.R;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class CustomAdapter extends BaseAdapter {
private Context mContext;
private ArrayListString mItems;
public CustomAdapter(Context c, ArrayListString items) {
mContext = c;
mItems = items;
}
@Override
public int getCount() {
return mItems.size();
}
@Override
public Object getItem(int position) {
return mItems.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup
parent)
{
View v = convertView;
if (v == null) {
LayoutInflater li =
[android-developers] Re: Reusing Views in Custom Adapter
You've hit the problem exactly YuvieDroid. Boy do I feel dumb. I
thought if the view was being re-used then the layout items on that
view were preserved as well. Moving the bracket on the if statement
fixed the issue immediately. Thanks!
On Nov 29, 1:44 pm, YuviDroid yuvidr...@gmail.com wrote:
You should always set the whole content of the layout in getView(). When
v is not null right now you are returning that view without setting your
text.
Something like this:
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater li = (LayoutInflater)
mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = li.inflate(R.layout.grid_item, null);
}
TextView tv = (TextView)v.findViewById(R.id.grid_item_text);
tv.setText(Item #+mItems.get(position));
return v;
}
On Tue, Nov 29, 2011 at 5:17 PM, Kumar Bibek coomar@gmail.com wrote:
What exactly is the problem. Bonkers doesn't really tell us much.
On Nov 29, 8:12 pm, authorwjf wfran...@softlayer.com wrote:
Hi Android Framework Gurus!
I am hoping someone out there can answer a question for me about re-
using views in my adapters. My understanding, is that for performance
reasons this is something I should always always always do. Yet in my
experience, doing so always results in the view, whether a grid or
list, going wonky once I get very many children in the view. I
suspect, I'm just doing something flat out wrong. So I put together a
simple straight-forward project to demonstrate both how I attempt to
re-use the views in a grid view, and how it goes bonkers if you add a
few hundred entries and scroll the list. I've tested on both the
cupcake emulator as well as my gingerbread device with the same
results.
Thanks in advance to anyone who takes the time to respond!
==Layouts==
main.xml
?xml version=1.0 encoding=utf-8?
LinearLayout xmlns:android=http://schemas.android.com/apk/res/
android
android:layout_width=fill_parent
android:layout_height=fill_parent
android:orientation=vertical
TextView
android:layout_width=fill_parent
android:layout_height=wrap_content
android:text=Reuse Views Demo /
GridView
android:id=@+id/gridview
android:layout_width=fill_parent
android:layout_height=fill_parent
android:padding=5dp
android:verticalSpacing=5dp
android:horizontalSpacing=10dp
android:numColumns=auto_fit
android:columnWidth=60dp
android:stretchMode=columnWidth
android:gravity=center_horizontal/
/LinearLayout
grid_item.xml
LinearLayout xmlns:android=http://schemas.android.com/apk/res/
android
android:id=@+id/GridItem
android:layout_width=fill_parent
android:layout_height=wrap_content
android:orientation=vertical
android:gravity=center_horizontal
TextView android:id=@+id/grid_item_text
android:layout_width=wrap_content
android:layout_height=wrap_content
android:gravity=center_horizontal
android:layout_marginBottom=4dip/
/LinearLayout
==source==
Main.java
package com.authorwjf.reuseviews;
import java.util.ArrayList;
import android.app.Activity;
import android.os.Bundle;
import android.widget.GridView;
public class Main extends Activity {
private CustomAdapter mAdapter;
private ArrayListString mItems = new ArrayListString();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
for (int i = 0; i200; i++) {
mItems.add(Integer.toString(i));
}
mAdapter = new CustomAdapter(this, mItems);
GridView g = (GridView) findViewById(R.id.gridview);
g.setAdapter(mAdapter);
}
}
CustomAdapter.java
package com.authorwjf.reuseviews;
import java.util.ArrayList;
import com.authorwjf.reuseviews.R;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class CustomAdapter extends BaseAdapter {
private Context mContext;
private ArrayListString mItems;
public CustomAdapter(Context c, ArrayListString items) {
mContext = c;
mItems = items;
}
@Override
public int getCount() {
return mItems.size();
}
@Override
public Object getItem(int position) {
