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

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;
    }

} 

其他回答

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。

这段代码很容易理解。

three_horizontal_text_views_layout.xml

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

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/leftTextView"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/centreTextView"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/rightTextView"/>

</LinearLayout>

ThreeStrings.java

public class ThreeStrings {
    private String left;
    private String right;
    private String centre;

    public ThreeStrings(String left, String right, String centre) {
        this.left = left;
        this.right = right;
        this.centre = centre;
    }
}

ThreeHorizontalTextViewsAdapter.java

public class ThreeHorizontalTextViewsAdapter extends ArrayAdapter<ThreeStrings> {

private int layoutResource;

public ThreeHorizontalTextViewsAdapter(Context context, int layoutResource, List<ThreeStrings> threeStringsList) {
    super(context, layoutResource, threeStringsList);
    this.layoutResource = layoutResource;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    View view = convertView;

    if (view == null) {
        LayoutInflater layoutInflater = LayoutInflater.from(getContext());
        view = layoutInflater.inflate(layoutResource, null);
    }

    ThreeStrings threeStrings = getItem(position);

    if (threeStrings != null) {
        TextView leftTextView = (TextView) view.findViewById(R.id.leftTextView);
        TextView rightTextView = (TextView) view.findViewById(R.id.rightTextView);
        TextView centreTextView = (TextView) view.findViewById(R.id.centreTextView);

        if (leftTextView != null) {
            leftTextView.setText(threeStrings.getLeft());
        }
        if (rightTextView != null) {
            rightTextView.setText(threeStrings.getRight());
        }
        if (centreTextView != null) {
            centreTextView.setText(threeStrings.getCentre());
        }
    }

    return view;
}
      }

main_layout.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context="com.androidapplication.ListActivity">


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

</LinearLayout>

MainActivity.java

public class MainActivity extends Activity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        List<ThreeStrings> threeStringsList = new ArrayList<>();
        ThreeStrings threeStrings = new ThreeStrings("a", "b", "c");
        threeStringsList.add(threeStrings);        
        ListView listView = (ListView)findViewById(R.id.listView);
        ThreeHorizontalTextViewsAdapter threeHorizontalTextViewsAdapter = new ThreeHorizontalTextViewsAdapter(this, R.layout.three_horizontal_text_views_layout, threeStringsList);
        listView.setAdapter(threeHorizontalTextViewsAdapter);
      }
   //......}

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

您可以在官方ApiDemos中查看这个示例。它展示了如何扩展BaseAdapter并将其应用到ListView。在此之后,只需查看BaseAdapter的引用,并尝试理解每个方法做什么(包括继承的方法)以及何时/如何使用它。

另外,谷歌是你的朋友:)。

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