如何在Android中为列表视图项目的单独组件（部件）启动一项新活动

Question

我为我的Android应用程序创建了一个ListView，并且为项目的单独部分创建单独的onClickListeners时出现问题。我的项目有一个image1，image2和一个文本。我想要的是根据哪些被点击而开始不同的活动。以下是我的代码。

**MainActivity.java** 
public class MainActivity extends Activity { 
    ListView mListView; 
    ImageView rightarrow; 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     // URL to the JSON data   
     String strUrl = "url of php file"; 

     // Creating a new non-ui thread task to download json data 
     DownloadTask downloadTask = new DownloadTask(); 

     // Starting the download process 
     downloadTask.execute(strUrl); 
    } 


    /** A method to download json data from url */ 
    private String downloadUrl(String strUrl) throws IOException{ 
     String data = ""; 
     InputStream iStream = null; 
     try{ 
       URL url = new URL(strUrl); 

       // Creating an http connection to communicate with url 
       HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); 

       // Connecting to url 
       urlConnection.connect(); 

       // Reading data from url 
       iStream = urlConnection.getInputStream(); 

       BufferedReader br = new BufferedReader(new InputStreamReader(iStream)); 

       StringBuffer sb = new StringBuffer(); 

       String line = ""; 
       while((line = br.readLine()) != null){ 
        sb.append(line); 
       } 

       data = sb.toString(); 

       br.close(); 

     }catch(Exception e){ 
       Log.d("Exception while downloading url", e.toString()); 
     }finally{ 
       iStream.close(); 
     } 

     return data; 
    } 





/** AsyncTask to download json data */ 
     private class DownloadTask extends AsyncTask<String, Integer, String>{ 
      String data = null; 
        @Override 
        protected String doInBackground(String... url) { 
          try{ 
           data = downloadUrl(url[0]); 

          }catch(Exception e){ 
           Log.d("Background Task",e.toString()); 
          } 
          return data; 
        } 

        @Override 
        protected void onPostExecute(String result) { 

          // The parsing of the xml data is done in a non-ui thread 
          ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask(); 

          // Start parsing xml data 
          listViewLoaderTask.execute(result);       

        } 
     } 



/** AsyncTask to parse json data and load ListView */ 
     private class ListViewLoaderTask extends AsyncTask<String, Void, SimpleAdapter>{ 

      JSONObject jObject; 
      // Doing the parsing of xml data in a non-ui thread 
      @Override 
      protected SimpleAdapter doInBackground(String... strJson) { 
       try{ 
        jObject = new JSONObject(strJson[0]); 
        CountryJSONParser countryJsonParser = new CountryJSONParser(); 
        countryJsonParser.parse(jObject); 
       }catch(Exception e){ 
        Log.d("JSON Exception1",e.toString()); 
       } 

       // Instantiating json parser class 
       CountryJSONParser countryJsonParser = new CountryJSONParser(); 

       // A list object to store the parsed countries list 
       List<HashMap<String, Object>> countries = null; 

       try{ 
        // Getting the parsed data as a List construct 
        countries = countryJsonParser.parse(jObject); 
       }catch(Exception e){ 
        Log.d("Exception",e.toString()); 
       }   

       // Keys used in Hashmap 
       // String[] from = { "country","flag","details"}; 
       String[] from = {"flag"}; 
       // Ids of views in listview_layout 
       // int[] to = { R.id.tv_country,R.id.iv_flag,R.id.tv_country_details}; 
       int[] to = { R.id.iv_flag}; 

       // Instantiating an adapter to store each items 
       // R.layout.listview_layout defines the layout of each item   
       SimpleAdapter adapter = new SimpleAdapter(getBaseContext(), countries, R.layout.lv_layout, from, to); 

       return adapter; 
      } 

      /** Invoked by the Android on "doInBackground" is executed */ 
      @Override 
      protected void onPostExecute(SimpleAdapter adapter) { 

       // Setting adapter for the listview 
       mListView.setAdapter(adapter); 

       for(int i=0;i<adapter.getCount();i++){ 
        HashMap<String, Object> hm = (HashMap<String, Object>) adapter.getItem(i); 
        String imgUrl = (String) hm.get("flag_path"); 
        ImageLoaderTask imageLoaderTask = new ImageLoaderTask(); 

        HashMap<String, Object> hmDownload = new HashMap<String, Object>(); 
        hm.put("flag_path",imgUrl); 
        hm.put("position", i); 

        // Starting ImageLoaderTask to download and populate image in the listview 
        imageLoaderTask.execute(hm); 

        } 
      } 

     } 



/** AsyncTask to download and load an image in ListView */ 
     private class ImageLoaderTask extends AsyncTask<HashMap<String, Object>, Void, HashMap<String, Object>>{ 

      @Override 
      protected HashMap<String, Object> doInBackground(HashMap<String, Object>... hm) { 

       InputStream iStream=null; 
       String imgUrl = (String) hm[0].get("flag_path"); 
       int position = (Integer) hm[0].get("position"); 

       URL url; 
       try { 
        url = new URL(imgUrl); 

        // Creating an http connection to communicate with url 
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); 

        // Connecting to url     
        urlConnection.connect(); 

        // Reading data from url 
        iStream = urlConnection.getInputStream(); 

        // Getting Caching directory 
        File cacheDirectory = getBaseContext().getCacheDir(); 

        // Temporary file to store the downloaded image 
        File tmpFile = new File(cacheDirectory.getPath() + "/wpta_"+position+".png"); 



        // tmpFile.getParentFile().mkdirs(); 
        // tmpFile.createNewFile(); 
        // The FileOutputStream to the temporary file 
        FileOutputStream fOutStream = new FileOutputStream(tmpFile); 

        // Creating a bitmap from the downloaded inputstream 
        Bitmap b = BitmapFactory.decodeStream(iStream);    

        // Writing the bitmap to the temporary file as png file 
        b.compress(Bitmap.CompressFormat.PNG,100, fOutStream);    

        // Flush the FileOutputStream 
        fOutStream.flush(); 

        //Close the FileOutputStream 
        fOutStream.close();    

        // Create a hashmap object to store image path and its position in the listview 
        HashMap<String, Object> hmBitmap = new HashMap<String, Object>(); 

        // Storing the path to the temporary image file 
        hmBitmap.put("flag",tmpFile.getPath()); 

        // Storing the position of the image in the listview 
        hmBitmap.put("position",position);    

        // Returning the HashMap object containing the image path and position 
        return hmBitmap;     


       }catch (Exception e) {    
        e.printStackTrace(); 
       } 
       return null; 
      } 

      @Override 
      protected void onPostExecute(HashMap<String, Object> result) { 
       // Getting the path to the downloaded image 
       String path = (String) result.get("flag");   

       // Getting the position of the downloaded image 
       int position = (Integer) result.get("position"); 

       // Getting adapter of the listview 
       SimpleAdapter adapter = (SimpleAdapter) mListView.getAdapter(); 

       // Getting the hashmap object at the specified position of the listview 
       HashMap<String, Object> hm = (HashMap<String, Object>) adapter.getItem(position); 

       // Overwriting the existing path in the adapter 
       hm.put("flag",path); 

       // Noticing listview about the dataset changes 
       adapter.notifyDataSetChanged(); 
      } 
     } 

     @Override 
     public boolean onCreateOptionsMenu(Menu menu) { 
      getMenuInflater().inflate(R.menu.activity_main, menu); 

      return true; 
     } 
    } 

我得到我从database.because ListViewListView内容是父视图，以便当我申请名单上观看clicklistener它得到它的每个项目的组件应用。所以我想ListView行及其组件开始不同的活动。 这里是我的适配器类：

public class CountryJSONParser { 

// Receives a JSONObject and returns a list 
public List<HashMap<String,Object>> parse(JSONObject jObject){  

    JSONArray jCountries = null; 
    try {  
     // Retrieves all the elements in the 'countries' array 
     jCountries = jObject.getJSONArray("countries"); 
    } catch (JSONException e) { 
     e.printStackTrace(); 
    } 

    // Invoking getCountries with the array of json object 
    // where each json object represent a country 
    return getCountries(jCountries); 
} 


private List<HashMap<String, Object>> getCountries(JSONArray jCountries){ 
    int countryCount = jCountries.length(); 
    List<HashMap<String, Object>> countryList = new ArrayList<HashMap<String,Object>>(); 
    HashMap<String, Object> country = null; 

    // Taking each country, parses and adds to list object 
    for(int i=0; i<countryCount;i++){ 
     try { 
      // Call getCountry with country JSON object to parse the country 
      country = getCountry((JSONObject)jCountries.get(i)); 
      countryList.add(country); 

     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
    } 

    return countryList; 
} 

// Parsing the Country JSON object 
private HashMap<String, Object> getCountry(JSONObject jCountry){ 

    HashMap<String, Object> country = new HashMap<String, Object>(); 

    String flag=""; 


    } catch (JSONException e) {   
     e.printStackTrace(); 
    }  
    return country; 
    } 
    } 

这里是我的XML文件：一个用于ListView等是ListView项目：

**activity_main.xml** 
<RelativeLayout 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" >  


    <ListView 
     android:id="@+id/lv_countries" 
     android:layout_width="fill_parent" 
     android:layout_height="fill_parent" 
     tools:context=".MainActivity" 
    android:background="@drawable/gradient_drawable" 
     android:dividerHeight="1dp" 
     android:divider="#b5b5b5" /> 


</RelativeLayout> 

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

    <TextView 
     android:id="@+id/tv_country" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_centerHorizontal="true" 

     android:textSize="20dp" 
     android:textStyle="bold" /> 

    <ImageView 
     android:id="@+id/iv_flag" 
     android:layout_width="80dp" 
     android:layout_height="80dp" 

     android:layout_centerVertical="true" 
     android:padding="5dp" 
     android:contentDescription="@string/str_iv_flag" /> 


     <ImageView 
     android:id="@+id/right_arrow" 
     android:layout_width="20dp" 
     android:layout_height="20dp" 
     android:src="@drawable/arrow2" 

     android:layout_alignParentRight="true" 
     android:layout_centerVertical="true"/> 

    <TextView 
     android:id="@+id/tv_country_details" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_toRightOf="@id/iv_flag" 

     android:layout_below="@id/tv_country" /> 

    </RelativeLayout> 

我已经尝试了“How to set onClickListener for separate parts of custom listView item? [Android]”后 但没有解决我的问题，因为它确实带我一个新的活动意味着什么都没有发生，也没有得到任何错误。所以请帮我解决这个问题。

Answer 1

从获取点击的项目的文本listviewin听众，然后采取哪些活动应该在点击开始决定，从here

lv.setOnItemClickListener(new OnItemClickListener() 
{ 
    @Override 
    public void onItemClick(AdapterView<?> a, View v, int position, long id) 
    { 
     // In the following line "v" refers to the View returned by the `getView()` method; meaning the clicked View. 
     TextView txtName = (TextView)v.findViewById(R.id.yourTextViewID); 
     String name = txtName.getText().toString(); 
     switch(name) 
     { 
       case "nameOne": 
        Intent intent = new Intent(YourCurrentActivity.this, NameOneActivity.class); 
        startActivity(intent); 
        break; 

       case "nameTwo": 
        Intent intent = new Intent(YourCurrentActivity.this, NameTwoActivity.class); 
        startActivity(intent); 
        break; 

       //And so on and so forth.... 
     } 

    } 
}); 

Answer 2

采取内，您的BaseAdpter类设置onClickListener在每个项目上和在随后的onclick启动你想要这样的活动：

image1.setOnClickListener(this); 
image2.setOnClickListener(this); 
textview.ssetOnClickListener(this); 

然后

@Override 
public void onClick(View view) { 
switch(view.getId()){ 
case image1.getId(): 
mActivity.startAcivity(new Intent(mActivity,ActivityToStart.class)); 
break; 
case image2.getId(): 
mActivity.startAcivity(new Intent(mActivity,ActivityToStart.class)); 
break; 
.....and so on 
} 
}