从另一个方法访问变量

efzxgjgh  于 2021-07-09  发布在  Java
关注(0)|答案(2)|浏览(338)

我正在尝试提交当前位置的android用户注册表。我对android和java开发还不熟悉。当我试图访问名值对代码中onlocationchanged方法的mylat和mylan时,它无法同时找到这两个变量。如何访问名值对代码中的两个变量。

package com.imran;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

import com.google.android.gcm.GCMRegistrar;
import com.google.android.maps.MyLocationOverlay;

import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.StrictMode;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import android.app.Activity;
import android.content.Context;

public class Register extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);
        final EditText email_id = (EditText)  findViewById(R.id.email_id) ;
        final EditText name = (EditText) findViewById(R.id.name);
        final EditText password = (EditText) findViewById(R.id.password);
        Button button = (Button) findViewById(R.id.button1) ;

        //generate GCM id
        GCMRegistrar.checkDevice(this);
        GCMRegistrar.checkManifest(this);
        final String regId = GCMRegistrar.getRegistrationId(this);
        if (regId.equals("")) {
          GCMRegistrar.register(this, "12356");

        } else {
        String TAG = null;
        Log.v(TAG, regId);

        }
        //generate GCM id ended
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy); 
        //get current location

        LocationManager manager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
        LocationListener listner = new LocationListener() {

            @Override
            public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
                // TODO Auto-generated method stub

            }

            @Override
            public void onProviderEnabled(String arg0) {
                // TODO Auto-generated method stub

            }

            @Override
            public void onProviderDisabled(String arg0) {
                // TODO Auto-generated method stub

            }

            @Override
            public void onLocationChanged(Location location) {
                double myLonDouble = location.getLongitude();
            final String myLon = Double.toString(myLonDouble);
                double myLatDouble = location.getLatitude();
                final String myLat = Double.toString(myLatDouble);

            }
        };
        manager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, listner);

        //end get current location

        button.setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View arg0) {
        // TODO Auto-generated method stub
        //postData();
          HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://xyz.com/folder/register.php");

            try {
                // Add your data
                List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
                nameValuePairs.add(new BasicNameValuePair("email", email_id.getText().toString()));
                nameValuePairs.add(new BasicNameValuePair("name", name.getText().toString()));
                nameValuePairs.add(new BasicNameValuePair("password", password.getText().toString()));
                nameValuePairs.add(new BasicNameValuePair("regid", regId));
                nameValuePairs.add(new BasicNameValuePair("uid", "2"));
                nameValuePairs.add(new BasicNameValuePair("lat",myLat ));
                nameValuePairs.add(new BasicNameValuePair("lon",myLon));
               httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

                // Execute HTTP Post Request
               //Toast.makeText(this, resId, duration)
                HttpResponse response = httpclient.execute(httppost);

            } catch (ClientProtocolException e) {
                // TODO Auto-generated catch block
            } catch (IOException e) {
                // TODO Auto-generated catch block
            }

    }
});

    }

}
des4xlb0

des4xlb01#

您可能应该进一步研究范围和成员变量。问题是,不能在一个方法中声明一个对象,然后尝试从另一个方法访问它。
所以,我们将它声明为一个成员变量,并在一个方法中定义它,然后可以在另一个方法中使用它。
像这样(我已经用 ** ):

public class Register extends Activity {

    // "private" means it can only be accessed from this class
    private String myLat = null; //**Declare myLat
    private String myLon = null; //**Declare myLon

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);
        final EditText email_id = (EditText)  findViewById(R.id.email_id) ;
        final EditText name = (EditText) findViewById(R.id.name);
        final EditText password = (EditText) findViewById(R.id.password);
        Button button = (Button) findViewById(R.id.button1) ;

        //generate GCM id
        GCMRegistrar.checkDevice(this);
        GCMRegistrar.checkManifest(this);
        final String regId = GCMRegistrar.getRegistrationId(this);
        if (regId.equals("")) {
          GCMRegistrar.register(this, "12356");

        } else {
        String TAG = null;
        Log.v(TAG, regId);

        }
        //generate GCM id ended
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy); 
        //get current location

        LocationManager manager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
        LocationListener listner = new LocationListener() {

            @Override
            public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
                // TODO Auto-generated method stub

            }

            @Override
            public void onProviderEnabled(String arg0) {
                // TODO Auto-generated method stub

            }

            @Override
            public void onProviderDisabled(String arg0) {
                // TODO Auto-generated method stub

            }

            @Override
            public void onLocationChanged(Location location) {
                double myLonDouble = location.getLongitude();
                myLon = Double.toString(myLonDouble); //**Define myLon
                double myLatDouble = location.getLatitude();
                myLat = Double.toString(myLatDouble); //**Define myLat

            }
        };
        manager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, listner);

        //end get current location

        button.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
        // TODO Auto-generated method stub
        //**Check if they have been defined
        if (myLat == null || myLon == null)
            return;

        //postData();
          HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://xyz.com/folder/register.php");

            try {
            // Add your data
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
            nameValuePairs.add(new BasicNameValuePair("email", email_id.getText().toString()));
            nameValuePairs.add(new BasicNameValuePair("name", name.getText().toString()));
            nameValuePairs.add(new BasicNameValuePair("password", password.getText().toString()));
            nameValuePairs.add(new BasicNameValuePair("regid", regId));
            nameValuePairs.add(new BasicNameValuePair("uid", "2"));
            nameValuePairs.add(new BasicNameValuePair("lat",myLat ));
            nameValuePairs.add(new BasicNameValuePair("lon",myLon));
               httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

            // Execute HTTP Post Request
               //Toast.makeText(this, resId, duration)
            HttpResponse response = httpclient.execute(httppost);

            } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            } catch (IOException e) {
            // TODO Auto-generated catch block
            }

        }
    });

    }

}
mjqavswn

mjqavswn2#

变量的范围有问题。您正在初始化的mylatdouble和mylon double只存在于创建它们的onlocationchanged方法中。您必须在不同的位置声明它们,以便在尝试访问它们时它们不会超出范围,或者必须将它们作为参数传递到namevaluepairs代码中

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