按钮不起作用

Question

我正在开发一个应用程序..在我的MainActivity中，一旦主要布局出现，用户就会得到一个按钮，这会导致另一个类。不幸的是，当我按下按钮没有任何反应时，我在手机上运行了应用程序。

下面我已经包含了按钮功能和按下按钮后要调用的类。

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;
}



}

PlacesMapActivity.java类

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;
}

}

请帮我解决问题。 谢谢

Answer 1

一定要：

import android.view.View.OnClickListener;

btnShowOnMap上的MainActivity声明必须在onCreate()方法内：

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);

        }

    });