Android适配器和上下文菜单

Question

我是安卓系统的新手，我真的不懂适配器的用法吗？我一直在尝试制作ContextMenu，它会在点击列表中的一个项目时弹出：我的活动是这样的，没有我尝试的ContextMenu，因为它很有用：

public class Proj2Activity extends Activity {
public static final String TAG = "MyActivity";
private TweetListAdapter1 twa;
private ListView myListView;
ArrayList<TweetModel> tweets;
public static double distance(float lat_a, float lng_a, float lat_b, float lng_b) {
    float pk = (float) (180/3.14169);
    float a1 = lat_a / pk;
    float a2 = lng_a / pk;
    float b1 = lat_b / pk;
    float b2 = lng_b / pk;
    float t1 = FloatMath.cos(a1)*FloatMath.cos(a2)*FloatMath.cos(b1)*FloatMath.cos(b2);
    float t2 = FloatMath.cos(a1)*FloatMath.sin(a2)*FloatMath.cos(b1)*FloatMath.sin(b2);
    float t3 = FloatMath.sin(a1)*FloatMath.sin(b1);
    double tt = Math.acos(t1 + t2 + t3);
    return 6366000*tt;
}

public static Location getLocation(Context ctx) {
    LocationManager lm = (LocationManager) ctx
            .getSystemService(Context.LOCATION_SERVICE);
    List<String> providers = lm.getProviders(true);
    /*
     * Loop over the array backwards, and if you get an accurate location,
     * then break out the loop
     */
    Location l = null;
    for (int i = providers.size() - 1; i >= 0; i--) {
        l = lm.getLastKnownLocation(providers.get(i));
        if (l != null)
            break;
    }
    return l;
}


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    LoadTweetsTask ltt = new LoadTweetsTask("androiddev");
    ltt.execute();

    final TextView text1 = (TextView) findViewById(R.id.nume);
    final Button btnGo = (Button) findViewById(R.id.button1);
    btnGo.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            String name1 = text1.getText().toString();
            SharedPreferences settings = getSharedPreferences("My_Pref", 0);
              SharedPreferences.Editor editor = settings.edit();
              editor.putBoolean(name1, true);
              editor.commit();
             LoadTweetsTask ltt = new LoadTweetsTask(name1);
             ltt.execute();
        }
    });

}


private class LoadTweetsTask extends AsyncTask<Void, Void, Void> {
    ProgressDialog progressDialog;
    public String name;

    public LoadTweetsTask(String name) {
        this.name = name;
    }
    @Override
    protected void onPreExecute() {
        tweets = new ArrayList<TweetModel>();
        progressDialog = new ProgressDialog(Proj2Activity.this);
        progressDialog.setMessage("Loading Tweets");
        progressDialog.show();
    }
    @Override
    protected void onPostExecute(Void result) {
        progressDialog.dismiss();
        TweetListAdapter1 adapter = new TweetListAdapter1(getApplicationContext(), tweets);
        ((ListView)findViewById(R.id.listTweets)).setAdapter(adapter);
    }
    @Override
    protected Void doInBackground(Void... params) {

        HttpClient client = new DefaultHttpClient();
        String requestUrl = "http://api.twitter.com/1/statuses/user_timeline.json" + "?screen_name=" + name + "&count=200";
        HttpGet request = new HttpGet(requestUrl);
        ResponseHandler<String> responseHandler = new BasicResponseHandler();
        try {
            String jsonResponse = client.execute(request, responseHandler);
            JSONArray json = new JSONArray(jsonResponse);
            //used to display 20 valid tweets from 200 tweets which have the location specified
            int count = 0;
            for (int i = 0; i < json.length(); i++) {
                if(count <= 20){
                    JSONObject jsonTweet = json.getJSONObject(i);
                    try{
                        JSONObject obj = jsonTweet.getJSONObject("geo");
                        if(obj!=null){
                            Location myLocation = getLocation(getBaseContext());
                            double distance;
                            JSONArray arr = obj.getJSONArray("coordinates");
                            float tweetc1 = (float) arr.getDouble(0);
                            float tweetc2 = (float) arr.getDouble(1);
                            Log.d("COORDTweet",Float.toString(tweetc1)+  "  " +Float.toString(tweetc2) );
                            float my1 = (float) 44.438254;
                            float my2 = (float) 26.051009;
                            Log.d("COORDMY",Float.toString(my1)+  "  " +Float.toString(my2) );
                            distance = distance(tweetc1, tweetc2, my1, my2);
                            Log.d("Distance",Double.toString(distance));
                            tweets.add(new TweetModel(jsonTweet.getJSONObject("user").getString("name"), jsonTweet.getString("created_at"), jsonTweet.getString("text"),(int)distance/1000));
                            count++;
                        }
                        Log.d("TRY", "OK");
                    }catch(JSONException e){
                        Log.d("EXCP","NULL");
                    }
                }
                else{
                    break;
                }
            }
        }
        catch(ClientProtocolException e) {
            Log.e(TAG, e.getMessage(), e);
        }
        catch (IOException e ) {
            Log.e(TAG, e.getMessage(), e);
        }
        catch (JSONException e ) {
            Log.e(TAG, e.getMessage(), e);
        }
        return null;
    }
}
}

适配器类：

public class TweetListAdapter1 extends BaseAdapter {
Context context;
ArrayList<TweetModel> items;
public TweetListAdapter1(Context context, ArrayList<TweetModel> items) {
    this.context = context;
    this.items = items;
}
public int getCount() {
    return items.size();
}
public Object getItem(int arg0) {
    // TODO Auto-generated method stub
    return null;
}
public long getItemId(int arg0) {
    // TODO Auto-generated method stub
    return 0;
}
public View getView(int position, View convertView, ViewGroup parent) {
    LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View rowView = inflater.inflate(R.layout.list_item_tweet, parent, false);
    TextView txtMessage = (TextView)rowView.findViewById(R.id.txtMessage);
    TweetModel m = items.get(position);
    txtMessage.setText("Name: " + m.getName()  +"n"+ "Distance :"+ m.getDistance() +  " Kmn" + "Tweet: " +  m.getTweet() + "n" + "Date: " + m.getDate() + "n");
    TextView txtMessage1 = (TextView)rowView.findViewById(R.id.txtMessage1);
    txtMessage1.setText("Ala bala ");
    return rowView;
}
}

我想做的是用两个操作打开上下文菜单：Action1和Action2。。。

Answer 1

我一直在尝试制作ContextMenu，它会在点击时弹出列表中的项目

因此，您需要在Activity类中实现它。

首先需要覆盖onCreateContextMenu，然后也覆盖onContextItemSelected方法

@Override
    public void onCreateContextMenu(ContextMenu cMenu, View parent, ContextMenu.ContextMenuInfo info) {
        new MenuInflater(YourActivity.this).inflate(R.menu.conmenu, cMenu);
    }
@Override
    public boolean onContextItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.option1:
                //do some work
                        break;
                        case R.id.option2:
                               // do some work
                        break;
            }
        ... 
    }

您需要阅读一些教程，以便Android: Context menu example和Context Menu | Android Developer Tutorial