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

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

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);
import android.app.Activity;

import android.content.Context;

import android.text.Html;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseAdapter;

import android.widget.ImageView;

import android.widget.TextView;

import org.json.JSONObject;

import java.util.ArrayList;

public class OurteamAdapter extends BaseAdapter {

    Context cont;
    ArrayList<OurteamModel> llist;
    OurteamAdapter madap;
    LayoutInflater inflater;
    JsonHelper Jobj;
    String Id;
    JSONObject obj = null;
    int position = 0;
    public OurteamAdapter(Context c,ArrayList<OurteamModel> Mi)
    {
        this.cont = c;
        this.llist = Mi;
    }
    @Override
    public int getCount()
    {
        // TODO Auto-generated method stub
        return llist.size();
    }
    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return llist.get(position);
    }
    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }
    @Override
    public View getView(final int position, View convertView, ViewGroup parent)
    {
        // TODO Auto-generated method stub
        if(convertView == null)
        {
            LayoutInflater in = (LayoutInflater) cont.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
            convertView = in.inflate(R.layout.doctorlist, null);
        }
        TextView category = (TextView) convertView.findViewById(R.id.button1);
        TextView title = (TextView) convertView.findViewById(R.id.button2);
        ImageView i1=(ImageView) convertView.findViewById(R.id.imageView1);
        category.setText(Html.fromHtml(llist.get(position).getGalleryName()));
        title.setText(Html.fromHtml(llist.get(position).getGalleryDetail()));
        if(llist.get(position).getImagesrc()!=null)
        {
            i1.setImageBitmap(llist.get(position).getImagesrc());
        }
        else
        {
            i1.setImageResource(R.drawable.anandlogo);
        }
        return convertView;
    }

}

我知道这个问题已经有人回答了……但我想给出一个更完整的例子。

在我的例子中,ListActivity将显示我们的自定义ListView被称为OptionsActivity,因为在我的项目中,这个活动将显示我的用户可以设置来控制我的应用程序的不同选项。有两种列表项类型,一种列表项类型只是有一个TextView和第二个列表项类型只是有一个按钮。您可以在每个列表项类型中放入任何您喜欢的小部件,但是我保持这个示例的简单性。

getItemView()方法检查哪些列表项应该是类型1或类型2。根据我在上面定义的静态整数,前5个列表项将是列表项类型1,后5个列表项将是列表项类型2。如果你编译并运行这个,你会有一个ListView,它有五个项目,只包含一个按钮,然后五个项目,只包含一个TextView。

下面是活动代码、活动xml文件和每个列表项类型的xml文件。

OptionsActivity.java:

public class OptionsActivity extends ListActivity {

    private static final int LIST_ITEM_TYPE_1 = 0;
    private static final int LIST_ITEM_TYPE_2 = 1;
    private static final int LIST_ITEM_TYPE_COUNT = 2;

    private static final int LIST_ITEM_COUNT = 10;
    // The first five list items will be list item type 1 
    // and the last five will be list item type 2
    private static final int LIST_ITEM_TYPE_1_COUNT = 5;

    private MyCustomAdapter mAdapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mAdapter = new MyCustomAdapter();
        for (int i = 0; i < LIST_ITEM_COUNT; i++) {
          if (i < LIST_ITEM_TYPE_1_COUNT)
            mAdapter.addItem("item type 1");
          else
            mAdapter.addItem("item type 2");
        }
        setListAdapter(mAdapter);
    }

    private class MyCustomAdapter extends BaseAdapter {

        private ArrayList<String> mData = new ArrayList<String>();
        private LayoutInflater mInflater;

        public MyCustomAdapter() {
            mInflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }

        public void addItem(final String item) {
            mData.add(item);
            notifyDataSetChanged();
        }

        @Override
        public int getItemViewType(int position) {
          if(position < LIST_ITEM_TYPE_1_COUNT)
              return LIST_ITEM_TYPE_1;
          else
              return LIST_ITEM_TYPE_2;
        }

        @Override
        public int getViewTypeCount() {
            return LIST_ITEM_TYPE_COUNT;
        }

        @Override
        public int getCount() {
            return mData.size();
        }

        @Override
        public String getItem(int position) {
            return mData.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder holder = null;
            int type = getItemViewType(position);
            if (convertView == null) {
                holder = new ViewHolder();
                switch(type) {
                    case LIST_ITEM_TYPE_1:
                        convertView = mInflater.inflate(R.layout.list_item_type1, null);
                        holder.textView = (TextView)convertView.findViewById(R.id.list_item_type1_text_view);
                        break;
                    case LIST_ITEM_TYPE_2:
                        convertView = mInflater.inflate(R.layout.list_item_type2, null);
                        holder.textView = (TextView)convertView.findViewById(R.id.list_item_type2_button);
                        break;
                }
                convertView.setTag(holder);
            } else {
                holder = (ViewHolder)convertView.getTag();
            }
            holder.textView.setText(mData.get(position));
            return convertView;
        }

    }

    public static class ViewHolder {
        public TextView textView;
    }

}

activity_options.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
     >

    <ListView
        android:id="@+id/optionsList"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >
    </ListView>

</LinearLayout>

list_item_type_1.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/list_item_type1_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/list_item_type1_text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Text goes here" />

</LinearLayout>

list_item_type2.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/list_item_type2_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/list_item_type2_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button text goes here" />

</LinearLayout>

一个更紧凑的自定义适配器的例子(使用列表数组作为我的数据):

class MyAdapter extends ArrayAdapter<Object> {
    public ArrayAdapter(Context context, List<MyObject> objectList) {
        super(context, R.layout.my_list_item, R.id.textViewTitle, objectList.toArray());
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = super.getView(position, convertView, parent);
        TextView title = (TextView) row.findViewById(R.id.textViewTitle);
        ImageView icon = (ImageView) row.findViewById(R.id.imageViewAccessory);
        MyObject obj = (MyObject) getItem(position);
        icon.setImageBitmap( ... );
        title.setText(obj.name);
        return row;
    }
}

下面是如何使用它:

List<MyObject> objectList = ...
MyAdapter adapter = new MyAdapter(this.getActivity(), objectList);
listView.setAdapter(adapter);