How to display a list of images in a ListView in Android?
How do I display a list of images using the ListView? I am dowloading the images at run time. The total number of images is not fixed.
I'd start with something like this (and if there is something wrong with my code, I'd of course appreciate any comment):
public class ItemsList extends ListActivity {
private ItemsAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.items_list);
this.adapter = new ItemsAdapter(this, R.layout.items_list_item, ItemManager.getLoadedItems());
setListAdapter(this.adapter);
}
private class ItemsAdapter extends ArrayAdapter<Item> {
private Item[] items;
public ItemsAdapter(Context context, int textViewResourceId, Item[] items) {
super(context, textViewResourceId, items);
this.items = items;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.items_list_item, null);
}
Item it = items[position];
if (it != null) {
ImageView iv = (ImageView) v.findViewById(R.id.list_item_image);
if (iv != null) {
iv.setImageDrawable(it.getImage());
}
}
return v;
}
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
this.adapter.getItem(position).click(this.getApplicationContext());
}
}
Eg extending ArrayAdapter with own type of Items (holding information about your pictures) and overriden getView() method, that prepares view for items within list. There is also method add() on ArrayAdapter to add items to the end of the list.
R.layout.items_list is simple layout with ListView
R.layout.items_list_item is layout representing one item in list
package studRecords.one;
import java.util.List;
import java.util.Vector;
import android.app.Activity;
import android.app.ListActivity;
import android.content.Context;
import android.content.Intent;
import android.net.ParseException;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
public class studRecords extends ListActivity
{
static String listName = "";
static String listUsn = "";
static Integer images;
private LayoutInflater layoutx;
private Vector<RowData> listValue;
RowData rd;
static final String[] names = new String[]
{
"Name (Stud1)", "Name (Stud2)",
"Name (Stud3)","Name (Stud4)"
};
static final String[] usn = new String[]
{
"1PI08CS016","1PI08CS007","1PI08CS017","1PI08CS047"
};
private Integer[] imgid =
{
R.drawable.stud1,R.drawable.stud2,R.drawable.stud3,
R.drawable.stud4
};
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.mainlist);
layoutx = (LayoutInflater) getSystemService(
Activity.LAYOUT_INFLATER_SERVICE);
listValue = new Vector<RowData>();
for(int i=0;i<names.length;i++)
{
try
{
rd = new RowData(names[i],usn[i],i);
}
catch (ParseException e)
{
e.printStackTrace();
}
listValue.add(rd);
}
CustomAdapter adapter = new CustomAdapter(this, R.layout.list,
R.id.detail, listValue);
setListAdapter(adapter);
getListView().setTextFilterEnabled(true);
}
public void onListItemClick(ListView parent, View v, int position,long id)
{
listName = names[position];
listUsn = usn[position];
images = imgid[position];
Intent myIntent = new Intent();
Intent setClassName = myIntent.setClassName("studRecords.one","studRecords.one.nextList");
startActivity(myIntent);
}
private class RowData
{
protected String mNames;
protected String mUsn;
protected int mId;
RowData(String title,String detail,int id){
mId=id;
mNames = title;
mUsn = detail;
}
@Override
public String toString()
{
return mNames+" "+mUsn+" "+mId;
}
}
private class CustomAdapter extends ArrayAdapter<RowData>
{
public CustomAdapter(Context context, int resource,
int textViewResourceId, List<RowData> objects)
{
super(context, resource, textViewResourceId, objects);
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
ViewHolder holder = null;
TextView title = null;
TextView detail = null;
ImageView i11=null;
RowData rowData= getItem(position);
if(null == convertView)
{
convertView = layoutx.inflate(R.layout.list, null);
holder = new ViewHolder(convertView);
convertView.setTag(holder);
}
holder = (ViewHolder) convertView.getTag();
i11=holder.getImage();
i11.setImageResource(imgid[rowData.mId]);
title = holder.gettitle();
title.setText(rowData.mNames);
detail = holder.getdetail();
detail.setText(rowData.mUsn);
return convertView;
}
private class ViewHolder
{
private View mRow;
private TextView title = null;
private TextView detail = null;
private ImageView i11=null;
public ViewHolder(View row)
{
mRow = row;
}
public TextView gettitle()
{
if(null == title)
{
title = (TextView) mRow.findViewById(R.id.title);
}
return title;
}
public TextView getdetail()
{
if(null == detail)
{
detail = (TextView) mRow.findViewById(R.id.detail);
}
return detail;
}
public ImageView getImage()
{
if(null == i11)
{
i11 = (ImageView) mRow.findViewById(R.id.img);
}
return i11;
}
}
}
}
//mainlist.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
Six years on, this is still at the top for some searches. Things have changed a lot since then. Now the defacto standard is more or less to use Volley and the NetworkImageView which takes care of the heavy lifting for you.
Assuming that you already have your Apaters, Loaders and ListFragments setup properly, this official google tutorial explains how to use NetworkImageView to load the images. Images are automatically loaded in a background thread and the view updated on the UI thread. It even supports caching.
链接地址: http://www.djcxy.com/p/93114.html上一篇: 发布延迟加载图像到ListView中