Wie erhalte ich von meiner App die Nachricht "Net not connected" anstelle des Absturzes

Question

Meine App stürzt ab und ich kann den Fehler nicht finden.

Ich möchte es mir eine Nachricht sagen, dass das Netzwerk nicht verbunden ist.

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.io.UnsupportedEncodingException; 
import java.util.ArrayList; 
import java.util.List; 
import org.apache.http.HttpEntity; 
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 org.json.JSONException; 
import org.json.JSONObject; 
import android.app.Activity; 
import android.app.Dialog; 
import android.app.ProgressDialog; 
import android.content.Intent; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.EditText; 
import android.widget.Toast; 


public class SimpleForm extends Activity { 

private EditText editTextUserName; 
private EditText editTextPassword; 

//public static final String USER_NAME = "USERNAME"; 

String username; 
String password; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_registeration); 

    editTextUserName = (EditText) findViewById(R.id.et_username_ID); 
    editTextPassword = (EditText) findViewById(R.id.et_pass_ID); 

} 

public void invokeLogin(View view){ 
    username = editTextUserName.getText().toString(); 
    password = editTextPassword.getText().toString(); 


    login(username,password); 

} 

private void login(final String username, String password) { 

    class LoginAsync extends AsyncTask<String, Void, String>{ 

     private Dialog loadingDialog; 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
      loadingDialog = ProgressDialog.show(SimpleForm .this, "Please wait", "Loading..."); 
     } 

     @Override 
     protected String doInBackground(String... params) { 
      //String uname = params[0]; 
      // String pass = params[1]; 


      JSONObject jsonObject = new JSONObject(); 
      try { 
       jsonObject.accumulate("username", params[0]); 
      } catch (JSONException e4) { 
       // TODO Auto-generated catch block 
       e4.printStackTrace(); 
      } 
      try { 
       jsonObject.accumulate("password", params[1]); 
      } catch (JSONException e3) { 
       // TODO Auto-generated catch block 
       e3.printStackTrace(); 
      } 
      try { 
       jsonObject.accumulate("deviceToken", "2324h5gj345gj3h4g5j"); 
      } catch (JSONException e5) { 
       // TODO Auto-generated catch block 
       e5.printStackTrace(); 
      } 
      try { 
       jsonObject.accumulate("os", "android"); 
      } catch (JSONException e2) { 
       // TODO Auto-generated catch block 
       e2.printStackTrace(); 
      } 
      try { 
       jsonObject.accumulate("key", "MEu07MgiuWgXwJOo7Oe1aHL0yM8P"); 
      } catch (JSONException e1) { 
       // TODO Auto-generated catch block 
       e1.printStackTrace(); 
      } 


      // 4. convert JSONObject to JSON to String 
      String dataString = jsonObject.toString(); 



      //String dataString = {"username":"apitest","password":"123456","deviceToken":"2324h5gj345gj3h4g5j34g","os":"andriod","key":"MEu07MgiuWgXwJOo7Oe1aHL0yM8VvP"} 
      InputStream is = null; 
      List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(); 
      nameValuePairs.add(new BasicNameValuePair("data", dataString)); 
      //nameValuePairs.add(new BasicNameValuePair("password", pass)); 
      String result = null; 

      try{ 
       HttpClient httpClient = new DefaultHttpClient(); 
       HttpPost httpPost = new HttpPost(
         "http://mobile.betfan.com/api/?action=login"); 
       //http://mobile.betfan.com/api/?action=login 
       //http://192.168.1.10/mobiletest/process.php 
       httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); 

       HttpResponse response = httpClient.execute(httpPost); 

       HttpEntity entity = response.getEntity(); 

       is = entity.getContent(); 

       BufferedReader reader = new BufferedReader(new InputStreamReader(is, "UTF-8"), 8); 
       StringBuilder sb = new StringBuilder(); 

       String line = null; 
       while ((line = reader.readLine()) != null) 
       { 
        sb.append(line + "\n"); 
       } 
       result = sb.toString(); 
      } catch (ClientProtocolException e) { 
       e.printStackTrace(); 
      } catch (UnsupportedEncodingException e) { 
       e.printStackTrace(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
      return result; 
     } 

     protected void onPostExecute(String result){ 
      String s = result.trim(); 
      loadingDialog.dismiss(); 

       JSONObject respObject; 
       try { 
        respObject = new JSONObject(s); 
        String active = respObject.getString("status_message"); 

        if(active.equalsIgnoreCase("success")){ 
         Toast.makeText(getApplicationContext(), s+"Login successfull", Toast.LENGTH_LONG).show(); 

         Intent intent=new Intent(SimpleForm.this,Welcome.class); 
         startActivity(intent); 
         // Intent intent = new Intent(MainActivity.this, UserProfile.class); 
         //intent.putExtra(USER_NAME, username); 
         // finish(); 
         //startActivity(intent); 
        }else { 
         Toast.makeText(getApplicationContext(), "Login Fail", Toast.LENGTH_LONG).show(); 

        } 

       } catch (JSONException e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
       } 



     } 
    } 

    LoginAsync la = new LoginAsync(); 
    la.execute(username, password); 

} 


@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.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); 
    } 
    } 

Answer 1

Bevor Sie Code verwenden, die Netzwerkverbindung erfordert, können Sie eine Methode, wie dies für die Konnektivität überprüfen anrufen:

private boolean isConnected() { 
    ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); 
    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo(); 
    return networkInfo != null && networkInfo.isConnectedOrConnecting(); 
}