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
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。
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)。
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);
}
//......}
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;
}
}
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
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