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我是一個初學者，這可能是我在這裏失蹤的編程基礎知識，但這是我將學習這些東西的唯一方法。android studio從不同的方法訪問一個對象的屬性
下面是我的MainActivity代碼。它試圖獲取最後一個位置的細節，並將它們讀入我定義的類（類稱爲UserCurrentAddress），以便我可以使用這些細節。
我已經在MainActivity類中聲明瞭UserCurrentAddress類，然後在onCreate中實例化了這個類。然後，我使用代碼底部的按鈕單擊（onClickView）來連接API並獲取位置。 「handleNewLocation」方法最終會填充UserCurrentAddress對象（並且可以成功運行）。但是，當我嘗試從buttonClick事件中的UserCurrentAddress中讀取這些詳細信息（僅使用Toast）時，它將返回爲空。如果我把這個吐司放在「handleNewLocation」中，那麼它是正確填充的。 爲什麼UserCurrentAddress的屬性在buttonClick事件中不可見？
我認爲通過在活動類中聲明它可以在整個過程中看到它。
我意識到我可以在「handleNewLocation」方法中做我需要做的事情，但最好從該事件外部訪問這些屬性。
我希望我能解釋我的問題。
代碼：
package com.example.android.trainingapp;
import android.content.IntentSender;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.model.LatLng;
import java.io.IOException;
import java.util.List;
import java.util.Locale;
public class MainActivity extends AppCompatActivity
implements GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
View.OnClickListener{
private GoogleApiClient mGoogleAPIClient;
private UserCurrentAddress userCurrentAddress;
Button bFindLocation;
private LocationRequest mlocationRequest;
private final static int CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bFindLocation = (Button) findViewById(R.id.show_location);
bFindLocation.setOnClickListener(this);
mGoogleAPIClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mlocationRequest = LocationRequest.create()
.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
.setInterval(10 * 1000)
.setFastestInterval(1 * 1000);
userCurrentAddress = new UserCurrentAddress(null, null, null, null, null, 0, 0, null);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onConnected(Bundle bundle) {
Location location = LocationServices.FusedLocationApi.getLastLocation(mGoogleAPIClient);
if(location==null){
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleAPIClient, mlocationRequest, (LocationListener) this);
}
else{
handleNewLocation(location);
}
}
public void handleNewLocation(Location location){
double currentLatitude, currentLongitude;
String addressOne, addressTwo, streetNumber, country, fullAddress, postCode, myAdress;
currentLatitude = location.getLatitude();
currentLongitude = location.getLongitude();
LatLng latLng = new LatLng(currentLatitude, currentLongitude);
Geocoder geocoder = new Geocoder(this, Locale.getDefault());
try {
List<Address> addresses = geocoder.getFromLocation(currentLatitude, currentLongitude, 1);
if(addresses != null){
Address returnedAddress = addresses.get(0);
StringBuilder strReturnedAddress = new StringBuilder();
for(int i=0; i < returnedAddress.getMaxAddressLineIndex(); i++){
strReturnedAddress.append(returnedAddress.getAddressLine(i)).append(" ");
}
streetNumber = returnedAddress.getSubThoroughfare();
addressOne = returnedAddress.getThoroughfare(); //Beech Rd
addressTwo = returnedAddress.getLocality(); //durban north
postCode = returnedAddress.getPostalCode();
country = returnedAddress.getCountryName();
myAdress = strReturnedAddress.toString();
userCurrentAddress.streetNumber = streetNumber;
userCurrentAddress.addressOne = addressOne;
userCurrentAddress.addressTwo = addressTwo;
userCurrentAddress.postCode = postCode;
userCurrentAddress.country =country ;
userCurrentAddress.latitude = currentLatitude;
userCurrentAddress.longitude = currentLongitude;
userCurrentAddress.fullAddress = myAdress;
Toast.makeText(this, userCurrentAddress.streetNumber, Toast.LENGTH_LONG).show();
}
else{
myAdress = "No Address Returned";
}
} catch (IOException e) {
e.printStackTrace();
myAdress = "Cannot get address";
}
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
/*
* Google Play services can resolve some errors it detects.
* If the error has a resolution, try sending an Intent to
* start a Google Play services activity that can resolve
* error.
*/
if (connectionResult.hasResolution()) {
try {
// Start an Activity that tries to resolve the error
connectionResult.startResolutionForResult(this, CONNECTION_FAILURE_RESOLUTION_REQUEST);
/*
* Thrown if Google Play services canceled the original
* PendingIntent
*/
} catch (IntentSender.SendIntentException e) {
// Log the error
e.printStackTrace();
}
} else {
/*
* If no resolution is available, display a dialog to the
* user with the error.
*/
}
}
@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.show_location:
mGoogleAPIClient.connect();
Toast.makeText(this, userCurrentAddress.fullAddress, Toast.LENGTH_LONG).show();
}
}
}
你在哪裏試圖訪問它們？另一個活動，片段，方法？ –