更改minSDKVersion时发生NetworkOnMainThreadException错误

Question

I have developed a login and registrartion system and the code works fine when the minSDKVersion is set to 8,But when I change the minSDkVersion to higher versions say 11 or 12 the app crashes when I try to login or register.What changes should I make in the code so that i can run in higher versions.The LoginActivity.java file is as follows:

   package com.example.trial;

   import java.util.HashMap;

   import org.json.JSONException;
   import org.json.JSONObject;

   import android.app.Activity;
   import android.content.Intent;
   import android.os.Bundle;
   import android.util.Log;
   import android.view.View;
   import android.widget.Button;
   import android.widget.EditText;
   import android.widget.TextView;

   import com.example.trial.library.DatabaseHandler;
   import com.example.trial.library.UserFunctions;

    public class LoginActivity extends Activity {
Button btnLogin;
Button btnLinkToRegister;
EditText inputEmail;
EditText inputPassword;
TextView loginErrorMsg;

// JSON Response node names
private static String KEY_SUCCESS = "success";
private static String KEY_ERROR = "error";
private static String KEY_ERROR_MSG = "error_msg";
private static String KEY_UID = "uid";
private static String KEY_NAME = "name";
private static String KEY_EMAIL = "email";
private static String KEY_CREATED_AT = "created_at";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);

    // Importing all assets like buttons, text fields
    inputEmail = (EditText) findViewById(R.id.loginEmail);
    inputPassword = (EditText) findViewById(R.id.loginPassword);
    btnLogin = (Button) findViewById(R.id.btnLogin);
    btnLinkToRegister = (Button) findViewById(R.id.btnLinkToRegisterScreen);
    loginErrorMsg = (TextView) findViewById(R.id.login_error);

    // Login button Click Event
    btnLogin.setOnClickListener(new View.OnClickListener() {

        public void onClick(View view) {
            String email = inputEmail.getText().toString();
            String password = inputPassword.getText().toString();
            UserFunctions userFunction = new UserFunctions();
            Log.d("Button", "Login");
            JSONObject json = userFunction.loginUser(email, password);

            // check for login response
            try {
                if (json.getString(KEY_SUCCESS) != null) {
                    loginErrorMsg.setText("");
                    String res = json.getString(KEY_SUCCESS); 
                    if(Integer.parseInt(res) == 1){
                        // user successfully logged in
                        // Store user details in SQLite Database
                        DatabaseHandler db = new DatabaseHandler(getApplicationContext());
                        JSONObject json_user = json.getJSONObject("user");

                        // Clear all previous data in  database
                         userFunction.logoutUser(getApplicationContext());
                         db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL),  json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));                      

                        // Launch Dashboard Screen
                        Intent dashboard = new  Intent(getApplicationContext(), DashboardActivity.class);

                        // Close all views before launching Dashboard
                        dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                        startActivity(dashboard);

                        // Close Login Screen
                        finish();
                    }else{
                        // Error in login
                        loginErrorMsg.setText("Incorrect username/password");
                    }
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    });

    // Link to Register Screen
    btnLinkToRegister.setOnClickListener(new View.OnClickListener() {

        public void onClick(View view) {
            Intent i = new Intent(getApplicationContext(),
                    RegisterActivity.class);
            startActivity(i);
            finish();
        }
    });
     }
     }

The RegisterActivity.java file is:

    package com.example.trial;

    import org.json.JSONException;
    import org.json.JSONObject;

    import com.example.trial.library.DatabaseHandler;
    import com.example.trial.library.UserFunctions;

    import android.app.Activity;
    import android.content.Intent;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.TextView;

    public class RegisterActivity extends Activity {
Button btnRegister;
Button btnLinkToLogin;
EditText inputFullName;
EditText inputEmail;
EditText inputPassword;
TextView registerErrorMsg;

// JSON Response node names
private static String KEY_SUCCESS = "success";
private static String KEY_ERROR = "error";
private static String KEY_ERROR_MSG = "error_msg";
private static String KEY_UID = "uid";
private static String KEY_NAME = "name";
private static String KEY_EMAIL = "email";
private static String KEY_CREATED_AT = "created_at";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.register);

    // Importing all assets like buttons, text fields
    inputFullName = (EditText) findViewById(R.id.registerName);
    inputEmail = (EditText) findViewById(R.id.registerEmail);
    inputPassword = (EditText) findViewById(R.id.registerPassword);
    btnRegister = (Button) findViewById(R.id.btnRegister);
    btnLinkToLogin = (Button) findViewById(R.id.btnLinkToLoginScreen);
    registerErrorMsg = (TextView) findViewById(R.id.register_error);

    // Register Button Click event
    btnRegister.setOnClickListener(new View.OnClickListener() {         
        public void onClick(View view) {
            String name = inputFullName.getText().toString();
            String email = inputEmail.getText().toString();
            String password = inputPassword.getText().toString();
            UserFunctions userFunction = new UserFunctions();
            JSONObject json = userFunction.registerUser(name, email, password);

            // check for login response
            try {
                if (json.getString(KEY_SUCCESS) != null) {
                    registerErrorMsg.setText("");
                    String res = json.getString(KEY_SUCCESS); 
                    if(Integer.parseInt(res) == 1){
                        // user successfully registred
                        // Store user details in SQLite Database
                        DatabaseHandler db = new DatabaseHandler(getApplicationContext());
                        JSONObject json_user = json.getJSONObject("user");

                        // Clear all previous data in database
                        userFunction.logoutUser(getApplicationContext());
                        db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));                        
                        // Launch Dashboard Screen
                        Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class);
                        // Close all views before launching Dashboard
                        dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                        startActivity(dashboard);
                        // Close Registration Screen
                        finish();
                    }else{
                        // Error in registration
                        registerErrorMsg.setText("Error occured in registration");
                    }
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    });

    // Link to Login Screen
    btnLinkToLogin.setOnClickListener(new View.OnClickListener() {

        public void onClick(View view) {
            Intent i = new Intent(getApplicationContext(),
                    LoginActivity.class);
            startActivity(i);
            // Close Registration View
            finish();
        }
    });
      }
      }

The logcat looks like this:

   03-24 01:20:22.154: E/AndroidRuntime(1787): FATAL EXCEPTION: main
   03-24 01:20:22.154: E/AndroidRuntime(1787): android.os.NetworkOnMainThreadException
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1133)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at libcore.io.IoBridge.connect(IoBridge.java:112)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at java.net.Socket.connect(Socket.java:842)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at com.example.trial.library.JSONParser.getJSONFromUrl(JSONParser.java:47)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at com.example.trial.library.UserFunctions.loginUser(UserFunctions.java:43)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at com.example.trial.LoginActivity$1.onClick(LoginActivity.java:56)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at android.view.View.performClick(View.java:4240)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at android.view.View$PerformClick.run(View.java:17721)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at android.os.Handler.handleCallback(Handler.java:730)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at android.os.Handler.dispatchMessage(Handler.java:92)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at android.os.Looper.loop(Looper.java:137)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at android.app.ActivityThread.main(ActivityThread.java:5103)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at java.lang.reflect.Method.invokeNative(Native Method)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at java.lang.reflect.Method.invoke(Method.java:525)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
   03-24 01:20:22.154: E/AndroidRuntime(1787):  at dalvik.system.NativeStart.main(Native Method)

Answer 1

Here you can't perform your network operation on the UI thread as of api level 11.

So for that you have to use AsyncTask or Thread .

Example of AsyncTask.

 class DowloadTest extends AsyncTask<String, Integer, String>

 {
    @Override
    protected void onPreExecute() {
        pDialog = new ProgressDialog(YourActivityName.this);
        pDialog.setMessage("Please wait..");
        pDialog.setIndeterminate(true);
        pDialog.setCancelable(false);
        pDialog.show();
    };

    @Override
    protected String doInBackground(String... params) {
        // parse your data here
        return null;

    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);

        pDialog.dismiss();

        }

    }
}

and after that execute this function whenever you need it like,

  new DowloadTest().execute();

For more reference go Here

Answer 2

// you can add your json code in async task class

  class callservice extends AsyncTask<String, String, String>
  {
    private ProgressDialog pDialog;
    String message = "";
    private String result;

    /**
     * Before starting background thread Show Progress Dialog
     * */
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(MainActivity.this);
        pDialog.setCancelable(false);
        pDialog.show();
    }
    /**
     * getting All products from url
     * */
    protected String doInBackground(String... args)
    {
         // Write your json code which get data

    }

    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(String file_url)
    {
        // dismiss the dialog after getting all products
        if (pDialog != null)
            pDialog.dismiss();

    }
}

Answer 3

Bcoz of your SDK tools are maybe Upgrade version doesnt support.. for example you create your project in SDK min level is 8 but your android SDk version tools is APK level 19 means it may occurs so go to your SDk Folder and delete tools Folder and then Copy your cuurent version of SDk tools must be put it in your SDK Folder.
you are using low level APK version means it will generate this line bcoz you want to access high high level code in Upgrade version supported methods means this lines will shows of your methods..

@SuppressLint("NewApi")
@Override
public void onCreate(Bundle savedInstanceState) {

and also set this line in your activity

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
            int shortAnimTime = getResources().getInteger(
                    android.R.integer.config_shortAnimTime);
or 
if (android.os.Build.VERSION.SDK_INT > 9) {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);
    }


thank you.

Answer 4

I was also facing the same problem, solution which worked for me is :

If you don't wish to use AsyncTask in your activity, try adding below snippet in your onCreate of LoginActivity.java

if (android.os.Build.VERSION.SDK_INT > 9) {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);
    }

So this will save your time and effort for solving this error.

PS If you get error on these line after adding them to your activity, try cleaning your application. You can also try adding

@SuppressLint("NewApi") before oncreate method. like this,

@SuppressLint("NewApi")
@Override
public void onCreate(Bundle savedInstanceState) {

Hope this well help you too.