我想为列表视图创建一个自定义适配器。有没有任何文章可以告诉我如何创建一个,并解释它是如何工作的?
当前回答
这很简单。
import android.content.Context;
import android.content.DialogInterface;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.app.AlertDialog;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.List;
/**
* Created by Belal on 9/14/2017.
*/
//we need to extend the ArrayAdapter class as we are building an adapter
public class MyListAdapter extends ArrayAdapter<Hero> {
//the list values in the List of type hero
List<Hero> heroList;
//activity context
Context context;
//the layout resource file for the list items
int resource;
//constructor initializing the values
public MyListAdapter(Context context, int resource, List<Hero> heroList) {
super(context, resource, heroList);
this.context = context;
this.resource = resource;
this.heroList = heroList;
}
//this will return the ListView Item as a View
@NonNull
@Override
public View getView(final int position, @Nullable View convertView, @NonNull ViewGroup parent) {
//we need to get the view of the xml for our list item
//And for this we need a layoutinflater
LayoutInflater layoutInflater = LayoutInflater.from(context);
//getting the view
View view = layoutInflater.inflate(resource, null, false);
//getting the view elements of the list from the view
ImageView imageView = view.findViewById(R.id.imageView);
TextView textViewName = view.findViewById(R.id.textViewName);
TextView textViewTeam = view.findViewById(R.id.textViewTeam);
Button buttonDelete = view.findViewById(R.id.buttonDelete);
//getting the hero of the specified position
Hero hero = heroList.get(position);
//adding values to the list item
imageView.setImageDrawable(context.getResources().getDrawable(hero.getImage()));
textViewName.setText(hero.getName());
textViewTeam.setText(hero.getTeam());
//adding a click listener to the button to remove item from the list
buttonDelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//we will call this method to remove the selected value from the list
//we are passing the position which is to be removed in the method
removeHero(position);
}
});
//finally returning the view
return view;
}
//this method will remove the item from the list
private void removeHero(final int position) {
//Creating an alert dialog to confirm the deletion
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setTitle("Are you sure you want to delete this?");
//if the response is positive in the alert
builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
//removing the item
heroList.remove(position);
//reloading the list
notifyDataSetChanged();
}
});
//if response is negative nothing is being done
builder.setNegativeButton("No", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
}
});
//creating and displaying the alert dialog
AlertDialog alertDialog = builder.create();
alertDialog.show();
}
}
来源:自定义ListView Android教程
其他回答
检查这个链接,在非常简单的通过convertView,我们可以得到一行的布局,这将显示在listview(这是parentView)。
View v = convertView;
if (v == null) {
LayoutInflater vi;
vi = LayoutInflater.from(getContext());
v = vi.inflate(R.layout.itemlistrow, null);
}
使用position,你可以得到List<Item>的对象。
Item p = items.get(position);
在此之后,我们必须将对象的所需细节设置为标识的表单小部件。
if (p != null) {
TextView tt = (TextView) v.findViewById(R.id.id);
TextView tt1 = (TextView) v.findViewById(R.id.categoryId);
TextView tt3 = (TextView) v.findViewById(R.id.description);
if (tt != null) {
tt.setText(p.getId());
}
if (tt1 != null) {
tt1.setText(p.getCategory().getId());
}
if (tt3 != null) {
tt3.setText(p.getDescription());
}
}
然后它将返回构造的视图,该视图将附加到parentView(这是一个ListView/GridView)。
BaseAdapter是listview最好的自定义适配器。
Class MyAdapter extends BaseAdapter{}
它有许多函数,如getCount(), getView()等。
下面是逐步为列表视图创建自定义适配器的完整步骤
https://www.caveofprogramming.com/guest-posts/custom-listview-with-imageview-and-textview-in-android.html
public class CustomAdapter extends BaseAdapter{
String [] result;
Context context;
int [] imageId;
private static LayoutInflater inflater=null;
public CustomAdapter(MainActivity mainActivity, String[] prgmNameList, int[] prgmImages) {
// TODO Auto-generated constructor stub
result=prgmNameList;
context=mainActivity;
imageId=prgmImages;
inflater = ( LayoutInflater )context.
getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return result.length;
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
public class Holder
{
TextView tv;
ImageView img;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
Holder holder=new Holder();
View rowView;
rowView = inflater.inflate(R.layout.program_list, null);
holder.tv=(TextView) rowView.findViewById(R.id.textView1);
holder.img=(ImageView) rowView.findViewById(R.id.imageView1);
holder.tv.setText(result[position]);
holder.img.setImageResource(imageId[position]);
rowView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(context, "You Clicked "+result[position], Toast.LENGTH_LONG).show();
}
});
return rowView;
}
}
public class ListAdapter extends ArrayAdapter<Item> {
private int resourceLayout;
private Context mContext;
public ListAdapter(Context context, int resource, List<Item> items) {
super(context, resource, items);
this.resourceLayout = resource;
this.mContext = context;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater vi;
vi = LayoutInflater.from(mContext);
v = vi.inflate(resourceLayout, null);
}
Item p = getItem(position);
if (p != null) {
TextView tt1 = (TextView) v.findViewById(R.id.id);
TextView tt2 = (TextView) v.findViewById(R.id.categoryId);
TextView tt3 = (TextView) v.findViewById(R.id.description);
if (tt1 != null) {
tt1.setText(p.getId());
}
if (tt2 != null) {
tt2.setText(p.getCategory().getId());
}
if (tt3 != null) {
tt3.setText(p.getDescription());
}
}
return v;
}
}
这是我在项目中使用的一个类。你需要有一个你想要显示的项目的集合,在我的例子中是<Item>。你需要重写View getView(int position, View convertView, ViewGroup parent)方法。
itemlistrow定义了ListView的行。
<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="wrap_content" android:orientation="vertical"
android:layout_width="fill_parent">
<TableRow android:layout_width="fill_parent"
android:id="@+id/TableRow01"
android:layout_height="wrap_content">
<TextView android:textColor="#FFFFFF"
android:id="@+id/id"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="id" android:textStyle="bold"
android:gravity="left"
android:layout_weight="1"
android:typeface="monospace"
android:height="40sp" />
</TableRow>
<TableRow android:layout_height="wrap_content"
android:layout_width="fill_parent">
<TextView android:textColor="#FFFFFF"
android:id="@+id/categoryId"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="categoryId"
android:layout_weight="1"
android:height="20sp" />
<TextView android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_weight="1"
android:textColor="#FFFFFF"
android:gravity="right"
android:id="@+id/description"
android:text="description"
android:height="20sp" />
</TableRow>
</TableLayout>
在MainActivity中定义listview,
ListView yourListView = (ListView) findViewById(R.id.itemListView);
// get data from the table by the ListAdapter
ListAdapter customAdapter = new ListAdapter(this, R.layout.itemlistrow, List<yourItem>);
yourListView .setAdapter(customAdapter);
谷歌有一个名为EfficientAdapter的示例,在我看来,它是如何实现自定义适配器的最佳简单示例。http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/view/List14.html @CommonsWare很好地解释了上面例子中使用的模式 http://commonsware.com/Android/excerpt.pdf
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