[英]How can I store a value in my global variable and use it inside any method anywhere in activity
我正在尝试构建一个天气应用程序。我有一个 API 链接,我将其作为字符串变量,其 scope 是全局的,我有另一种方法来获取经度和纬度。 我想将这些纬度和经度值保存在我的变量中,其 scope 是全局的。 While I am inside my geocoder method where I am taking out latitude and longitude values (my global variable API link changes and gives me the desired result because I am concatenating longtiude and latitude with my variable whose scope is global. But once I go out of这种方法并尝试以不同的方法使用我的 API 链接(我丢失了我在地理编码器方法中获得并连接的纬度和经度值,希望它会永久改变我的全局变量值。
这是代码。 (我有 4-5 个文件,但我只粘贴了我实际工作的主要活动代码)如果我硬编码纬度和经度值,我会得到想要的结果,但我只是想通过获得纬度和经度来做得更好.
public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<List<Model>> {
public static final int WEATHERLOADER = 1;
RecyclerView recyclerView;
WeatherAdapter mAdapter;
List<Model> modelList;
FusedLocationProviderClient fusedLocation;
String latitude;
String longit;
Button getweather;
String APILINK = "http://api.openweathermap.org/data/2.5/weather?lat=";
String APIKEY = "&appid=5c161192e5aa828fc6a8896eddaf89e2";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getweather = findViewById(R.id.getWeather);
recyclerView = findViewById(R.id.recyclerview);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
modelList = new ArrayList<>();
mAdapter = new WeatherAdapter(this, modelList);
recyclerView.setAdapter(mAdapter);
ConnectivityManager conn = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
if (conn!=null) {
NetworkInfo networkInfo = conn.getActiveNetworkInfo();
if (networkInfo!=null){
LoaderManager loaderManager = getSupportLoaderManager();
loaderManager.initLoader(WEATHERLOADER, null, this);
}
}
fusedLocation = LocationServices.getFusedLocationProviderClient(this);
getweather.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED ) {
wantLocation();
} else {
ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 44);
}
}
});
}
private void wantLocation() {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
fusedLocation.getLastLocation().addOnCompleteListener(new OnCompleteListener<Location>() {
@Override
public void onComplete(@NonNull Task<Location> task) {
Location location = task.getResult();
if (location != null) {
try {
Geocoder geocoder = new Geocoder(
MainActivity.this, Locale.getDefault());
List<Address> addresses = geocoder.getFromLocation(location.getLatitude(), location.getLongitude(), 1);
/*cityname.setText(Html.fromHtml("<font color='#6200EE'><b>City Name:</b><br></font>" + addresses.get(0).getAdminArea()));
longtitude.setText(Html.fromHtml("<font color='#6200EE'><b>Longtitude:</b><br></font>" + addresses.get(0).getLongitude()));
lattitude.setText(Html.fromHtml("<font color='#6200EE'><b>Lattitude:</b><br></font>" + addresses.get(0).getLatitude()));
countryname.setText(Html.fromHtml("<font color='#6200EE'><b>Country Name:</b><br></font>" + addresses.get(0).getCountryName()));
*/
APILINK = APILINK + addresses.get(0).getLatitude() + "&lon=" + addresses.get(0).getLongitude() + APIKEY;
} catch (IOException e) {
e.printStackTrace();
}
}
}
});
}
@NonNull
@Override
public Loader<List<Model>> onCreateLoader(int i, @Nullable Bundle bundle) {
Toast.makeText(MainActivity.this, String.valueOf(APILINK), Toast.LENGTH_SHORT).show();
return new WeatherLoader(this, APILINK);
}
@Override
public void onLoadFinished(@NonNull Loader<List<Model>> loader, List<Model> modelList) {
if (modelList!=null && !modelList.isEmpty()) {
mAdapter = new WeatherAdapter(this, modelList);
recyclerView.setAdapter(mAdapter);
}
}
@Override
public void onLoaderReset(@NonNull Loader<List<Model>> loader) {
}
}
我不确定我是否完全理解问题/情况,但从提供的代码看来, APILINK应该在onComplete方法中正确修改。 如果您尝试从不同的 class 访问APILINK ,您可以创建一个“getter”方法,该方法在调用时返回 APILINK:
public String getAPILINK() {
return APILINK;
}
通过将 String 设置为getAPILINK() ,您可以在不同的类或方法中制作APILINK的副本。
编辑 1:要连接字符串,您只需像以前一样使用+运算符。 这可能意味着问题出在其他地方。 要进行故障排除,请尝试添加
System.out.println(APILINK);
到程序中的各个点,例如在调用onComplete之前和之后。 如果附加了“&lon=”和APIKEY ,但没有附加纬度和经度,那么问题在于检索这些值。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.