java - Android - 在 Activity 类 android.app.application 中找不到方法 playaudio(View)

Question

我现在被阻止了几个小时，我正在尝试使用 xml onClick 属性处理 ListView 内的按钮单击。

这是我的 result.xml:

<?xml version="1.0" encoding="utf-8"?>

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="5dp">

 <TextView
    android:id="@+id/url"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:visibility="gone"/>

<TextView
    android:id="@+id/title"
    style="@android:style/TextAppearance.Large"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_toLeftOf="@+id/play"
    android:singleLine="true"
    android:text="title"
    android:textColor="#000000" />

<TextView
    android:id="@+id/artist"
    style="@android:style/TextAppearance.Small"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_below="@id/title"
    android:layout_toLeftOf="@+id/play"
    android:singleLine="true"
    android:text="artist"
    android:textColor="#7D7D7D" />

<TextView
    android:id="@+id/duration"
    style="@android:style/TextAppearance.Small"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/artist"
    android:layout_alignParentBottom="true"
    android:layout_below="@id/artist"
    android:layout_toLeftOf="@+id/play"
    android:singleLine="true"
    android:text="03:24"
    android:textColor="#7D7D7D" />

<ImageButton
    android:id="@+id/play"
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:layout_toLeftOf="@+id/download"
    android:src="@drawable/play"
    android:onClick="playAudio" />

<ImageButton
    android:id="@+id/download"
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:layout_alignParentRight="true"
    android:src="@drawable/download" />

 </RelativeLayout>

这是我的 search.java 文件

 package com.example.testxxx;

 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.UnsupportedEncodingException;
 import java.net.URLEncoder;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 import org.apache.http.HttpResponse;
 import org.apache.http.client.HttpClient;
 import org.apache.http.client.methods.HttpGet;
 import org.apache.http.impl.client.DefaultHttpClient;
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;

 import android.app.ListActivity;
 import android.app.SearchManager;
 import android.content.Context;
 import android.content.Intent;
 import android.graphics.Color;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 import android.os.AsyncTask;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.View;
 import android.widget.Button;
 import android.widget.LinearLayout;
 import android.widget.ListView;
 import android.widget.SimpleAdapter;
 import android.widget.TextView;
 import android.widget.Toast;



 public class Search extends ListActivity {

    private TextView mTextView;
     private ListView mListView;
     private String query;
     private String queryencoded;
     private static Context mContext;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.search);

        mTextView = (TextView) findViewById(R.id.text);
        mListView = (ListView) findViewById(android.R.id.list);

        mContext = getApplicationContext();

        // Get the intent, verify the action and get the query
        Intent intent = getIntent();
        if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
          query = intent.getStringExtra(SearchManager.QUERY);
        try {
            queryencoded = URLEncoder.encode(query, "utf-8");
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
          Log.w("myApp", "aaaaa");
          Toast.makeText(Search.this, (query), Toast.LENGTH_LONG).show();


          mTextView.setText("testing connexion");

          if(isConnected()){
              mTextView.setText("Loading...");
              new HttpAsyncTask().execute("url to json");
          }
          else{
              mTextView.setBackgroundColor(0xffcc0000);
              mTextView.setText("You are NOT connected");
          } 
        }
    }

    public boolean isConnected(){
         ConnectivityManager connMgr = (ConnectivityManager) getSystemService(this.CONNECTIVITY_SERVICE);
             NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
             if (networkInfo != null && networkInfo.isConnected()) 
                 return true;
             else
                 return false;   
     }

    public static String GET(String url){
         InputStream inputStream = null;
         String result = "";
         try {

             // create HttpClient
             HttpClient httpclient = new DefaultHttpClient();

             // make GET request to the given URL
             HttpResponse httpResponse = httpclient.execute(new HttpGet(url));

             // receive response as inputStream
             inputStream = httpResponse.getEntity().getContent();

             // convert inputstream to string
             if(inputStream != null)
                 result = convertInputStreamToString(inputStream);
             else
                 result = "Did not work!";

         } catch (Exception e) {
             Log.d("InputStream", e.getLocalizedMessage());
         }

         return result;
     }

    private static String convertInputStreamToString(InputStream inputStream) throws IOException{
         BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(inputStream));
         String line = "";
         String result = "";
         while((line = bufferedReader.readLine()) != null)
             result += line;

         inputStream.close();
         return result;

     }

     private class HttpAsyncTask extends AsyncTask<String, Void, String> {
            @Override
            protected String doInBackground(String... urls) {

                return GET(urls[0]);
            }
            // onPostExecute displays the results of the AsyncTask.
            @Override
            protected void onPostExecute(String result) {
                Toast.makeText(getBaseContext(), "Received!", Toast.LENGTH_LONG).show();

                try {
                    JSONObject jsonobject = new JSONObject(result);
                    mTextView.setText((String) jsonobject.get("count"));

                    Integer count = Integer.parseInt((String) jsonobject.get("count"));

                    if (count == 0) {
                        // There are no results
                        mTextView.setText(getString(R.string.no_results, query));
                    } else {
                        // Display the number of results
                        String countString = getResources().getQuantityString(R.plurals.search_results,
                                count, new Object[] {count, query});
                        mTextView.setText(countString);



                        // Specify the columns we want to display in the result
                        String[] from = new String[] { "title",
                                                       "artist",
                                                       "duration",
                                                       "url"};

                        // Specify the corresponding layout elements where we want the columns to go
                        int[] to = new int[] { R.id.title,
                                               R.id.artist,
                                               R.id.duration,
                                               R.id.url};

                        // -- container for all of our list items
                        List<Map<String, String>> groupData = new ArrayList<Map<String, String>>();

                        // -- list item hash re-used
                        Map<String, String> group;

                        //create audio json array
                        JSONArray audios = jsonobject.getJSONArray("audio");

                        for (int i = 0; i < audios.length(); i++) {
                            JSONObject audio = audios.getJSONObject(i);

                            //get info
                            String title = audio.getString("title");
                            String artist = audio.getString("artist");
                            String duration = audio.getString("duration");
                            String durationformated = getDurationString(Integer.parseInt(duration));
                            String url = audio.getString("url");

                            // -- create record
                            group = new HashMap<String, String>();

                            group.put( "title", title );
                            group.put( "artist",  artist );
                            group.put( "duration",  durationformated );
                            group.put( "url",  url );

                            groupData.add(group);
                        }

                        SimpleAdapter adapter = new SimpleAdapter(mContext , groupData, R.layout.result, 
                                from,
                                 to );

                        setListAdapter( adapter );

                    }
                } 

                catch (JSONException e)           
                 {                
                    // TODO Auto-generated catch block   
                    Log.w("myApp", e);    
                 }
           }

            public void playAudio(View v) {

                //get the row the clicked button is in
                LinearLayout vwParentRow = (LinearLayout)v.getParent();

                TextView urlview = (TextView)vwParentRow.findViewById(R.id.url);
                String url = (String) urlview.getText();

                Toast.makeText(mContext, (url), Toast.LENGTH_LONG).show();

            }

        }

        private String getDurationString(int seconds) {

            int hours = seconds / 3600;
            int minutes = (seconds % 3600) / 60;
            seconds = seconds % 60;

            return twoDigitString(minutes) + ":" + twoDigitString(seconds);
        }

        private String twoDigitString(int number) {

            if (number == 0) {
                return "00";
            }

            if (number / 10 == 0) {
                return "0" + number;
            }

            return String.valueOf(number);
        }


 }

这是我得到的错误

 02-10 20:00:31.995: E/AndroidRuntime(19483): java.lang.IllegalStateException: Could          not find a method playAudio(View) in the activity class android.app.Application for onClick handler on view class android.widget.ImageButton with id 'play'

我尝试将 playAudio 方法放在 Search 类、HttpAsyncTask 和 MainActivity 类中，但没有任何效果，我仍然遇到相同的错误。

我还想知道为什么引用 android.app.application 类时出现错误，因为布局来自“搜索”> HttpAsyncTask

也许这就是错误的原因，但是我能做些什么来解决它呢？

非常感谢:)

Answer 1

这里

mContext = getApplicationContext();

意味着您正在使用Application作为Context(通常不是一个好主意。)

这里

SimpleAdapter adapter = new SimpleAdapter(mContext , groupData, R.layout.result

您在此适配器中使用该应用程序上下文，这意味着该上下文用于扩充 result.xml 布局。

结果是 onClick 参数在 Application 类中搜索 playAudio。

最后，public void playAudio(View v) { 不在您的 Activity 中，而是在您的 AsyncTask

为了解决这个问题，

• mContext = this; 另外，不要将其设置为静态
• 在Activity中移动playAudio
• 瞧!