如何创建自定义适配器列表视图 [英] How to create a listview with custom adapter
问题描述
我有以下的code:
package com.example.myfirstapp;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.UnknownHostException;
import java.util.ArrayList;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.TextView;
public class FetchData extends Activity {
private TextView textView;
private JSONObject jObject;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_fetch_data);
textView = (TextView) findViewById(R.id.TextView1);
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
readWebpage(message);
}
private class DownloadWebPageTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... urls) {
String response = "";
for (String url : urls) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
try {
HttpResponse execute = client.execute(httpGet);
InputStream content = execute.getEntity().getContent();
BufferedReader buffer = new BufferedReader(new InputStreamReader(content));
String s = "";
while ((s = buffer.readLine()) != null) {
response += s;
}
} catch (Exception e) {
e.printStackTrace();
}
}
return response;
mParseResponse(response);
}
@Override
protected void onPostExecute(String result) {
textView.setText(result);
}
}
public void readWebpage(String message) {
//Intent intent = getIntent();
//String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
DownloadWebPageTask task = new DownloadWebPageTask();
task.execute(new String[] {message});
}
ArrayList<String> year, title, details, director, rating, cover;
// For Parse Login Response From Server
public void mParseResponse(String response) throws UnknownHostException {
year=new ArrayList<String>();
title=new ArrayList<String>();
details=new ArrayList<String>();
director=new ArrayList<String>();
rating=new ArrayList<String>();
cover=new ArrayList<String>();
try {
JSONObject jObject = new JSONObject(response);
JSONObject jsonobjresults = jObject.getJSONObject("results");
JSONArray jsonarrayresult = jsonobjresults.getJSONArray("result");
for(int i=0;i<jsonarrayresult.length(); i++){
JSONObject mJsonObj = jsonarrayresult.getJSONObject(i);
year.add(mJsonObj.getString("year"));
title.add(mJsonObj.getString("title"));
details.add(mJsonObj.getString("details"));
director.add(mJsonObj.getString("director"));
rating.add(mJsonObj.getString("rating"));
cover.add(mJsonObj.getString("cover"));
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
我越来越困惑,如何创建一个自定义的适配器。是的,我已经thoeugh教程,但仍然混乱退出。另外,我有一个错误,当我做出mParseResponse打电话。任何想法,我错了,我应该如何实现列表视图?
I am getting confused as to how to create a custom adapter. Yes, i have gone thoeugh tutorials but confusion still exits. Plus, I am having an error when i make a call to mParseResponse. Any ideas where I am going wrong and how should i implement list view?
推荐答案
也许这种简单的来样定制适配器列表视图会得到你的脚这个东西。
主要活动
Perhaps this simple sample custom adapter listview will get on your feet with this stuff. The main activity
public class MainActivity extends Activity {
String [] children = {
"Award 1",
"Award 2",
"Award 3",
"Award 4",
"Award 5",
"Award 6",
"Award 7",
"Award 8",
"Award 9",
"Award 10",
"Award 11",
"Award 12",
"Award 13",
"Award 14",
"Award 15"};
@Override
public void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ListView list = (ListView) findViewById(R.id.listview);
CustomAdapter adapter = new CustomAdapter(this, children);
list.setAdapter(adapter);
}
自定义适配器
public class CustomAdapter extends BaseAdapter {
// you could have instead extend ArrayAdapter if you wished, i find it less fickle but less flexible
// extends CursorAdapter is available too for listviews backed by cursors
private LayoutInflater inflator;
private String[] children;
public CustomAdapter(Context context, String[] children) {
super();
// pass what you need into the constructor. in this case the string array and context.
// do as much as you can here and not in getView because getView acts for each row
// --> it will greatly help performance
this.children = children;
inflator = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
// v---- your listview won't show anything if this is left default (at 0).
return children.length;
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// getView is where all the action takes place
// first inflate the xml that holds the row and somehow connect it to convertView, the parameter
// checking if null allows these views to be recycled when they go off-screen not just made one per row
// ---> it will greatly help performance
if (convertView == null) {
convertView = inflator.inflate(R.layout.row, parent, false);
}
// then find the individual views with this xml (everything just like onCreate)
ImageView img = (ImageView) convertView.findViewById(R.id.imageView1);
TextView tv = (TextView) convertView.findViewById(R.id.textView1);
// then perform your actions to the your views
// each textView is set to an element in the array based on position. this is my listview limiter here.
// each imageview is set to the same picture but you should now have an idea how to set different images (based on position)
// using listview position in correspondence with array/arraylist positions is a very useful technique.
img.setImageResource(R.drawable.ic_launcher);
tv.setText(children[position]);
// v---- return your view, it's important.
return convertView;
}
}
row.xml
row.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<ImageView
android:id="@+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:src="@drawable/ic_launcher" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="TextView" />
</RelativeLayout>
结果
The result
要获得与列表视图超级熟悉看看这个视频:
http://www.youtube.com/watch?v=wDBM6wVEO70
To get super acquainted with listview check out this video: http://www.youtube.com/watch?v=wDBM6wVEO70
至于你的其他问题,你得来发布logcat的更好的响应。
As for your other issue, you're gonna have to post a logcat for better responses.
这篇关于如何创建自定义适配器列表视图的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!