按钮不起作用

Question

我正在开发一个应用程序..在我的MainActivity中，一旦出现主布局，用户会得到一个按钮，这会导致另一个类。我在手机上运行了应用程序，不幸的是，当我按下按钮时什么也没有发生。

下面我已经包含了按钮功能和按钮按下后调用的类。

package com.androidhive.googleplacesandmaps; 

import java.util.ArrayList; 
import java.util.HashMap; 

import android.app.Activity; 
import android.app.ProgressDialog; 
import android.content.Intent; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.text.Html; 
import android.util.Log; 
import android.view.Menu; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemClickListener; 
import android.widget.Button; 
import android.widget.ListAdapter; 
import android.widget.ListView; 
import android.widget.SimpleAdapter; 
import android.widget.TextView; 


public class MainActivity extends Activity { 

// flag for Internet connection status 
Boolean isInternetPresent = false; 

// Connection detector class 
ConnectionDetector cd; 

// Alert Dialog Manager 
AlertDialogManager alert = new AlertDialogManager(); 

// Google Places 
GooglePlaces googlePlaces; 

// Places List 
PlacesList nearPlaces; 

// GPS Location 
GPSTracker gps; 

// Button 
Button btnShowOnMap; 

// Progress dialog 
ProgressDialog pDialog; 

// Places Listview 
ListView lv; 

// ListItems data 
ArrayList<HashMap<String, String>> placesListItems = new ArrayList<HashMap<String,String>>(); 


// KEY Strings 
public static String KEY_REFERENCE = "reference"; // id of the place 
public static String KEY_NAME = "name"; // name of the place 
public static String KEY_VICINITY = "vicinity"; // Place area name 

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

    cd = new ConnectionDetector(getApplicationContext()); 

    // Check if Internet present 
    isInternetPresent = cd.isConnectingToInternet(); 
    if (!isInternetPresent) { 
     // Internet Connection is not present 
     alert.showAlertDialog(MainActivity.this, "Internet Connection Error", 
       "Please connect to working Internet connection", false); 
     // stop executing code by return 
     return; 
    } 

    // creating GPS Class object 
    gps = new GPSTracker(this); 

    // check if GPS location can get 
    if (gps.canGetLocation()) { 
     Log.d("Your Location", "latitude:" + gps.getLatitude() + ", longitude: " + gps.getLongitude()); 
    } else { 
     // Can't get user's current location 
     alert.showAlertDialog(MainActivity.this, "GPS Status", 
       "Couldn't get location information. Please enable GPS", 
       false); 
     // stop executing code by return 
     return; 
    } 

    // Getting listview 
    lv = (ListView) findViewById(R.id.list); 

    // button show on map 
    btnShowOnMap = (Button) findViewById(R.id.btn_show_map); 

    // calling background Async task to load Google Places 
    // After getting places from Google all the data is shown in listview 
    new LoadPlaces().execute(); 

    /** Button click event for shown on map */ 
    btnShowOnMap.setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View arg0) { 
      Intent i = new Intent(getApplicationContext(), 
        PlacesMapActivity.class); 
      // Sending user current geo location 
      i.putExtra("user_latitude", Double.toString(gps.getLatitude())); 
      i.putExtra("user_longitude", Double.toString(gps.getLongitude())); 

      // passing near places to map activity 
      i.putExtra("near_places", nearPlaces); 
      // staring activity 
      startActivity(i); 
     } 
    }); 


    /** 
    * ListItem click event 
    * On selecting a listitem SinglePlaceActivity is launched 
    * */ 
    lv.setOnItemClickListener(new OnItemClickListener() { 

     @Override 
     public void onItemClick(AdapterView<?> parent, View view, 
       int position, long id) { 
      // getting values from selected ListItem 
      String reference = ((TextView) view.findViewById(R.id.reference)).getText().toString(); 

      // Starting new intent 
      Intent in = new Intent(getApplicationContext(), 
        SinglePlaceActivity.class); 

      // Sending place refrence id to single place activity 
      // place refrence id used to get "Place full details" 
      in.putExtra(KEY_REFERENCE, reference); 
      startActivity(in); 
     } 
    }); 
} 

/** 
* Background Async Task to Load Google places 
* */ 
    class LoadPlaces extends AsyncTask<String, String, String> { 

    /** 
    * Before starting background thread Show Progress Dialog 
    * */ 
    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     pDialog = new ProgressDialog(MainActivity.this); 
     pDialog.setMessage(Html.fromHtml("<b>Search</b><br/>Loading Places...")); 
     pDialog.setIndeterminate(false); 
     pDialog.setCancelable(false); 
     pDialog.show(); 
    } 

    /** 
    * getting Places JSON 
    * */ 
    protected String doInBackground(String... args) { 
     // creating Places class object 
     googlePlaces = new GooglePlaces(); 

     try { 
      // Separeate your place types by PIPE symbol "|" 
      // If you want all types places make it as null 
      // Check list of types supported by google 
      // 
      String types = "hospital|pharmacy"; // Listing places only cafes, restaurants 

      // Radius in meters - increase this value if you don't find any places 
      double radius = 5000; // 5000 meters 

      // get nearest places 
      nearPlaces = googlePlaces.search(gps.getLatitude(), 
        gps.getLongitude(), radius, types); 


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

    /** 
    * After completing background task Dismiss the progress dialog 
    * and show the data in UI 
    * Always use runOnUiThread(new Runnable()) to update UI from background 
    * thread, otherwise you will get error 
    * **/ 
    protected void onPostExecute(String file_url) { 
     // dismiss the dialog after getting all products 
     pDialog.dismiss(); 
     // updating UI from Background Thread 
     runOnUiThread(new Runnable() { 
      public void run() { 
       /** 
       * Updating parsed Places into LISTVIEW 
       * */ 
       // Get json response status 
       String status = nearPlaces.status; 

       // Check for all possible status 
       if(status.equals("OK")){ 
        // Successfully got places details 
        if (nearPlaces.results != null) { 
         // loop through each place 
         for (Place p : nearPlaces.results) { 
          HashMap<String, String> map = new HashMap<String, String>(); 

          // Place reference won't display in listview - it will be hidden 
          // Place reference is used to get "place full details" 
          map.put(KEY_REFERENCE, p.reference); 

          // Place name 
          map.put(KEY_NAME, p.name); 


          // adding HashMap to ArrayList 
          placesListItems.add(map); 
         } 
         // list adapter 
         ListAdapter adapter = new SimpleAdapter(MainActivity.this,  placesListItems, 
           R.layout.list_item, 
           new String[] { KEY_REFERENCE, KEY_NAME}, new int[] { 
             R.id.reference, R.id.name }); 

         // Adding data into listview 
         lv.setAdapter(adapter); 
        } 
       } 
       else if(status.equals("ZERO_RESULTS")){ 
        // Zero results found 
        alert.showAlertDialog(MainActivity.this, "Near Places", 
          "Sorry no places found. Try to change the types of places", 
          false); 
       } 
       else if(status.equals("UNKNOWN_ERROR")) 
       { 
        alert.showAlertDialog(MainActivity.this, "Places Error", 
          "Sorry unknown error occured.", 
          false); 
       } 
       else if(status.equals("OVER_QUERY_LIMIT")) 
       { 
        alert.showAlertDialog(MainActivity.this, "Places Error", 
          "Sorry query limit to google places is reached", 
          false); 
       } 
       else if(status.equals("REQUEST_DENIED")) 
       { 
        alert.showAlertDialog(MainActivity.this, "Places Error", 
          "Sorry error occured. Request is denied", 
          false); 
       } 
       else if(status.equals("INVALID_REQUEST")) 
       { 
        alert.showAlertDialog(MainActivity.this, "Places Error", 
          "Sorry error occured. Invalid Request", 
          false); 
       } 
       else 
       { 
        alert.showAlertDialog(MainActivity.this, "Places Error", 
          "Sorry error occured.", 
          false); 
       } 
      } 
     }); 

    } 

} 

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



} 

类PlacesMapActivity.java

package com.stenlyjoseph.myhealth; 

import com.stenlyjoseph.myhealth.R; 

import java.util.List; 

import android.content.Intent; 
import android.graphics.drawable.Drawable; 
import android.os.Bundle; 
import android.util.Log; 

import com.google.android.maps.GeoPoint; 
import com.google.android.maps.MapActivity; 
import com.google.android.maps.MapController; 
import com.google.android.maps.MapView; 
import com.google.android.maps.Overlay; 
import com.google.android.maps.OverlayItem; 

public class PlacesMapActivity extends MapActivity { 
// Nearest places 
PlacesList nearPlaces; 

// Map view 
MapView mapView; 

// Map overlay items 
List<Overlay> mapOverlays; 

AddItemizedOverlay itemizedOverlay; 

GeoPoint geoPoint; 
// Map controllers 
MapController mc; 

double latitude; 
double longitude; 
OverlayItem overlayitem; 

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

    // Getting intent data 
    Intent i = getIntent(); 

    // Users current geo location 
    String user_latitude = i.getStringExtra("user_latitude"); 
    String user_longitude = i.getStringExtra("user_longitude"); 

    // Nearplaces list 
    nearPlaces = (PlacesList) i.getSerializableExtra("near_places"); 

    mapView = (MapView) findViewById(R.id.mapview); 
    mapView.setBuiltInZoomControls(true); 

    mapOverlays = mapView.getOverlays(); 

    // Geopoint to place on map 
    geoPoint = new GeoPoint((int) (Double.parseDouble(user_latitude) * 1E6), 
      (int) (Double.parseDouble(user_longitude) * 1E6)); 

    // Drawable marker icon 
    Drawable drawable_user = this.getResources() 
      .getDrawable(R.drawable.red); 

    itemizedOverlay = new AddItemizedOverlay(drawable_user, this); 

    // Map overlay item 
    overlayitem = new OverlayItem(geoPoint, "Your Location", 
      "That is you!"); 

    itemizedOverlay.addOverlay(overlayitem); 

    mapOverlays.add(itemizedOverlay); 
    itemizedOverlay.populateNow(); 

    // Drawable marker icon 
    Drawable drawable = this.getResources() 
      .getDrawable(R.drawable.blue); 

    itemizedOverlay = new AddItemizedOverlay(drawable, this); 

    mc = mapView.getController(); 

    // These values are used to get map boundary area 
    // The area where you can see all the markers on screen 
    int minLat = Integer.MAX_VALUE; 
    int minLong = Integer.MAX_VALUE; 
    int maxLat = Integer.MIN_VALUE; 
    int maxLong = Integer.MIN_VALUE; 

    // check for null in case it is null 
    if (nearPlaces.results != null) { 
     // loop through all the places 
     for (Place place : nearPlaces.results) { 
      latitude = place.geometry.location.lat; // latitude 
      longitude = place.geometry.location.lng; // longitude 

      // Geopoint to place on map 
      geoPoint = new GeoPoint((int) (latitude * 1E6), 
        (int) (longitude * 1E6)); 

      // Map overlay item 
      overlayitem = new OverlayItem(geoPoint, place.name, 
        place.vicinity); 

      itemizedOverlay.addOverlay(overlayitem); 


      // calculating map boundary area 
      minLat = (int) Math.min(geoPoint.getLatitudeE6(), minLat); 
      minLong = (int) Math.min(geoPoint.getLongitudeE6(), minLong); 
      maxLat = (int) Math.max(geoPoint.getLatitudeE6(), maxLat); 
      maxLong = (int) Math.max(geoPoint.getLongitudeE6(), maxLong); 
     } 
     mapOverlays.add(itemizedOverlay); 

     // showing all overlay items 
     itemizedOverlay.populateNow(); 
    } 

    // Adjusting the zoom level so that you can see all the markers on map 
    mapView.getController().zoomToSpan(Math.abs(minLat - maxLat), Math.abs(minLong - maxLong )); 

    // Showing the center of the map 
    mc.animateTo(new GeoPoint((maxLat + minLat)/2, (maxLong + minLong)/2)); 
    mapView.postInvalidate(); 

} 

@Override 
protected boolean isRouteDisplayed() { 
    return false; 
} 

} 

请帮我解决这个问题。 谢谢

Answer 1

一定要有：

import android.view.View.OnClickListener; 

和btnShowOnMap上MainActivity声明必须是onCreate()方法中：

Button btnShowOnMap = (Button)inflatedView.findViewById(R.id.yourbutton); 
btnShowOnMap.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View view) { 

      Intent i = new Intent(MainActivity.this, 
        PlacesMapActivity.class); 
      // Sending user current geo location 
      i.putExtra("user_latitude", Double.toString(gps.getLatitude())); 
      i.putExtra("user_longitude", Double.toString(gps.getLongitude())); 

      // passing near places to map activity 
      i.putExtra("near_places", nearPlaces); 
      // staring activity 
      startActivity(i); 

     } 

    });