MS SQL Server android connection

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MS SQL Server android connection

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#1 by (2 votes)

4

I have the following code for a login, but when executing the application, it is dropped by the OnClickListener method (server, and users of the bdd omitted for obvious reasons)

package com.ciclomapp.ciclomapp.ciclomapp;

import android.annotation.SuppressLint;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class Login extends AppCompatActivity {

    Button login;
    EditText username, password;


    Connection con;
    String un, pass, db, sv;


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

        login = (Button) findViewById(R.id.button);
        username = (EditText) findViewById(R.id.editText2);
        password = (EditText) findViewById(R.id.editText4);

        sv = "";
        db = "";
        un = "";
        pass = "";

        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                CheckLogin checkLogin = new CheckLogin();
                checkLogin.execute("");
            }
        });

    }


    public class CheckLogin extends AsyncTask <String, String, String> {
        String z = "";
        Boolean isSuccess = false;
        String usernam = username.getText().toString();
        String passwordd = password.getText().toString();

        @Override
        protected String doInBackground(String... params) {

            if (usernam.trim().equals("") || passwordd.trim().equals(""))
                z = "Please enter Username and Password";
            else {
                try {
                    con = connectionclass(sv, db, un, pass);       
                    if (con == null)
                    {
                        z = "Check Your Internet Access!";
                    }
                    else
                    {

                        String query = "select * from login where email= '" + usernam.toString() + "' and contraseña = '"+ passwordd.toString() +"'  ";
                        Statement stmt = con.createStatement();
                        ResultSet rs = stmt.executeQuery(query);
                        if(rs.next())
                        {
                            z = "Login successful";
                            isSuccess=true;
                            con.close();
                            Toast.makeText(Login.this, "correcto", Toast.LENGTH_SHORT).show();

                        }
                        else
                        {
                            z = "Invalid Credentials!";
                            isSuccess = false;
                        }
                    }
                }
                catch (Exception ex)
                {
                    isSuccess = false;
                    z = ex.getMessage();
                }
            }
            return z;
        }
    }


    @SuppressLint("NewApi")
    public Connection connectionclass(String user, String password, String database, String server)
    {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);
        Connection connection = null;
        String ConnectionURL = null;
        try
        {
            Class.forName("net.sourceforge.jtds.jdbc.Driver");
            ConnectionURL = "jdbc:jtds:sqlserver://" + server + database + ";user=" + user+ ";password=" + password + ";";
            connection = DriverManager.getConnection(ConnectionURL);
        }
        catch (SQLException se)
        {
            Log.e("error here 1 : ", se.getMessage());
        }
        catch (ClassNotFoundException e)
        {
            Log.e("error here 2 : ", e.getMessage());
        }
        catch (Exception e)
        {
            Log.e("error here 3 : ", e.getMessage());
        }
        return connection;
    }

}

here I leave the layout

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_login"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.ciclomapp.ciclomapp.ciclomapp.Login">

    <TextView
        android:text="E-Mail"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="230dp"
        android:id="@+id/textView11"
        android:textSize="25sp" />

    <TextView
        android:text="No tienes cuenta? Registrate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="14dp"
        android:id="@+id/textView9"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:textSize="20sp" />

    <TextView
        android:text="Contraseña"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="52dp"
        android:id="@+id/textView2"
        android:textSize="25sp"
        android:layout_below="@+id/textView11"
        android:layout_alignParentStart="true" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:ems="10"
        android:id="@+id/editText2"
        style="@android:style/Widget.AutoCompleteTextView"
        android:inputType="textEmailAddress"
        android:background="@android:color/darker_gray"
        android:layout_alignBottom="@+id/textView11"
        android:layout_alignTop="@+id/textView11"
        android:layout_alignParentEnd="true"
        android:layout_alignStart="@+id/editText4"
        android:textColor="@android:color/black"
        tools:ignore="LabelFor" />

    <Button
        android:text="Iniciar sesión"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button"
        android:layout_marginBottom="13dp"
        android:layout_above="@+id/textView9"
        android:layout_centerHorizontal="true"/>

    <EditText
        android:inputType="textPassword"
        android:ems="10"
        android:id="@+id/editText4"
        android:background="@android:color/darker_gray"
        android:layout_width="wrap_content"
        android:layout_height="35dp"
        android:textColor="@android:color/black"
        android:layout_alignBottom="@+id/textView2"
        android:layout_alignParentEnd="true" />

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:srcCompat="@drawable/logo"
        android:id="@+id/imageView2"
        android:layout_above="@+id/editText2"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

and the logcat

D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: com.ciclomapp.ciclomapp.ciclomapp, PID: 10120
                  java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ciclomapp.ciclomapp.ciclomapp/com.ciclomapp.ciclomapp.ciclomapp.Login}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2442)
                      at android.app.ActivityThread.access$800(ActivityThread.java:156)
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1351)
                      at android.os.Handler.dispatchMessage(Handler.java:102)
                      at android.os.Looper.loop(Looper.java:211)
                      at android.app.ActivityThread.main(ActivityThread.java:5371)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at java.lang.reflect.Method.invoke(Method.java:372)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:945)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:740)
                   Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
                      at com.ciclomapp.ciclomapp.ciclomapp.Login.onCreate(Login.java:51)
                      at android.app.Activity.performCreate(Activity.java:5990)
                      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2332)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2442) 
                      at android.app.ActivityThread.access$800(ActivityThread.java:156) 
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1351) 
                      at android.os.Handler.dispatchMessage(Handler.java:102) 
                      at android.os.Looper.loop(Looper.java:211) 
                      at android.app.ActivityThread.main(ActivityThread.java:5371) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at java.lang.reflect.Method.invoke(Method.java:372) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:945) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:740) 
Disconnected from the target VM, address: 'localhost:8600', transport: 'socket'

pd: Sorry to publish so much code

android sql-server

asked by zhet 02.10.2016 в 21:13

source

1 answer

Two linked selections (Country and Province) that do not link error in changing fontawesome icon

score 2 · Accepted Answer

The error is indicated in your message displayed in the LogCat:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener (android.view.View $ OnClickListener) ' on a null object reference at com

Generally this problem occurs when the instance of the "login" button does not exist in your layout activity_main.xml or has a different name:

setContentView(R.layout.activity_main;
            login = (Button) findViewById(R.id.button);

Update: When reviewing the layout, you have defined in the layout, for the button the property:

android:onClick="onClick"

Which causes conflict.

<Button
    android:text="Iniciar sesión"
    android:id="@+id/button"
    android:onClick="onClick" />

Remove this property:

android:onClick="onClick"

Since you are implementing a listener for this action.

How to call a method using the `android:onClick` property:

The method to be executed is defined:

<Button
     android:layout_height="wrap_content"
     android:layout_width="wrap_content"
     android:text="Click para realizar tarea."
     android:onClick="algunaTarea" />

And in the code, the method that receives the view as a parameter is defined:

public void algunaTarea(View view) {
     // Realiza tarea!
 }

MS SQL Server android connection

1 answer

How to call a method using the android:onClick property:

How to call a method using the `android:onClick` property: