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);
      }
   //......}

其他回答

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;
    }

}

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

数据模型

public class DataModel {
    String name;
    String type;
    String version_number;
    String feature;

    public DataModel(String name, String type, String version_number, String feature ) {
        this.name=name;
        this.type=type;
        this.version_number=version_number;
        this.feature=feature;

    }

    public String getName() {
        return name;
    }

    public String getType() {
        return type;
    }

    public String getVersion_number() {
        return version_number;
    }

    public String getFeature() {
        return feature;
    }    
}

数组适配器

public class CustomAdapter extends ArrayAdapter<DataModel> implements View.OnClickListener{
    private ArrayList<DataModel> dataSet;
    Context mContext;

    // View lookup cache
    private static class ViewHolder {
        TextView txtName;
        TextView txtType;
        TextView txtVersion;
        ImageView info;
    }

    public CustomAdapter(ArrayList<DataModel> data, Context context) {
        super(context, R.layout.row_item, data);
        this.dataSet = data;
        this.mContext=context;

    }

    @Override
    public void onClick(View v) {

        int position=(Integer) v.getTag();
        Object object= getItem(position);
        DataModel dataModel=(DataModel)object;

        switch (v.getId())
        {
            case R.id.item_info:
                Snackbar.make(v, "Release date " +dataModel.getFeature(), Snackbar.LENGTH_LONG)
                        .setAction("No action", null).show();
                break;
        }
    }

    private int lastPosition = -1;

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Get the data item for this position
        DataModel dataModel = getItem(position);
        // Check if an existing view is being reused, otherwise inflate the view
        ViewHolder viewHolder; // view lookup cache stored in tag

        final View result;

        if (convertView == null) {

            viewHolder = new ViewHolder();
            LayoutInflater inflater = LayoutInflater.from(getContext());
            convertView = inflater.inflate(R.layout.row_item, parent, false);
            viewHolder.txtName = (TextView) convertView.findViewById(R.id.name);
            viewHolder.txtType = (TextView) convertView.findViewById(R.id.type);
            viewHolder.txtVersion = (TextView) convertView.findViewById(R.id.version_number);
            viewHolder.info = (ImageView) convertView.findViewById(R.id.item_info);

            result=convertView;

            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
            result=convertView;
        }

        Animation animation = AnimationUtils.loadAnimation(mContext, (position > lastPosition) ? R.anim.up_from_bottom : R.anim.down_from_top);
        result.startAnimation(animation);
        lastPosition = position;

        viewHolder.txtName.setText(dataModel.getName());
        viewHolder.txtType.setText(dataModel.getType());
        viewHolder.txtVersion.setText(dataModel.getVersion_number());
        viewHolder.info.setOnClickListener(this);
        viewHolder.info.setTag(position);
        // Return the completed view to render on screen
        return convertView;
    }
}

主要活动

public class MainActivity extends AppCompatActivity {

    ArrayList<DataModel> dataModels;
    ListView listView;
    private static CustomAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        listView=(ListView)findViewById(R.id.list);

        dataModels= new ArrayList<>();

        dataModels.add(new DataModel("Apple Pie", "Android 1.0", "1","September 23, 2008"));
        dataModels.add(new DataModel("Banana Bread", "Android 1.1", "2","February 9, 2009"));
        dataModels.add(new DataModel("Cupcake", "Android 1.5", "3","April 27, 2009"));
        dataModels.add(new DataModel("Donut","Android 1.6","4","September 15, 2009"));
        dataModels.add(new DataModel("Eclair", "Android 2.0", "5","October 26, 2009"));
        dataModels.add(new DataModel("Froyo", "Android 2.2", "8","May 20, 2010"));
        dataModels.add(new DataModel("Gingerbread", "Android 2.3", "9","December 6, 2010"));
        dataModels.add(new DataModel("Honeycomb","Android 3.0","11","February 22, 2011"));
        dataModels.add(new DataModel("Ice Cream Sandwich", "Android 4.0", "14","October 18, 2011"));
        dataModels.add(new DataModel("Jelly Bean", "Android 4.2", "16","July 9, 2012"));
        dataModels.add(new DataModel("Kitkat", "Android 4.4", "19","October 31, 2013"));
        dataModels.add(new DataModel("Lollipop","Android 5.0","21","November 12, 2014"));
        dataModels.add(new DataModel("Marshmallow", "Android 6.0", "23","October 5, 2015"));

        adapter= new CustomAdapter(dataModels,getApplicationContext());

        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                DataModel dataModel= dataModels.get(position);

                Snackbar.make(view, dataModel.getName()+"\n"+dataModel.getType()+" API: "+dataModel.getVersion_number(), Snackbar.LENGTH_LONG)
                        .setAction("No action", null).show();
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

row_item.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="10dp">

    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:text="Marshmallow"
        android:textAppearance="?android:attr/textAppearanceSmall"
        android:textColor="@android:color/black" />


    <TextView
        android:id="@+id/type"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/name"
        android:layout_marginTop="5dp"
        android:text="Android 6.0"
        android:textColor="@android:color/black" />

    <ImageView
        android:id="@+id/item_info"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true"
        android:src="@android:drawable/ic_dialog_info" />


    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true">

        <TextView
            android:id="@+id/version_heading"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="API: "
            android:textColor="@android:color/black"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/version_number"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="23"
            android:textAppearance="?android:attr/textAppearanceButton"
            android:textColor="@android:color/black"
            android:textStyle="bold" />

    </LinearLayout>

</RelativeLayout>

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);
      }
   //......}