package com.xcore.xserver.link;

import android.content.Intent;
import android.database.Cursor;
import android.database.SQLException;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import OpenHelper.SQLite_OpenHelper;

public class MainActivity extends AppCompatActivity {

    Button btnLogin;
    Button btnregaccess;
    EditText loginboxEmail;
    EditText loginboxPasswort;

    SQLite_OpenHelper helper=new SQLite_OpenHelper(this,"ConfidentialDB",null,1);

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

        btnregaccess= (Button) findViewById(R.id.register);

        btnregaccess.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent regintent = new Intent(MainActivity.this, Register.class);
                MainActivity.this.startActivity(regintent);

        }
        });

        btnLogin=(Button) findViewById(R.id.btn_login);
        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                 loginboxEmail=(EditText) findViewById(R.id.loginbox_email);
                 loginboxPasswort=(EditText) findViewById(R.id.loginbox_passwort);

                try {
                    Cursor cursor=helper.verifyuserpass(loginboxEmail.getText().toString(),loginboxPasswort.getText().toString());

                    if (cursor.getCount()>0) {
                        Intent i=new Intent(getApplicationContext(),homepage.class);
                        startActivity(i);
                    } else {
                        Toast.makeText(getApplicationContext(),"correo y/o contraseña incorrectos",Toast.LENGTH_LONG).show();
                    }
                    loginboxEmail.setText("");
                    loginboxPasswort.setText("");
                    loginboxEmail.findFocus();

                } catch (SQLException e) {
                    e.printStackTrace();
                }

            }
        });

    }
}

package OpenHelper;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class SQLite_OpenHelper extends SQLiteOpenHelper {

    public SQLite_OpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);

    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String query="create table usersregist(_ID integer primary key autoincrement, Vorname text, Straße text, Email text, Passwort text);";
        db.execSQL(query);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

    // open database
    public void opendb(){
        this.getWritableDatabase();
    }
    // close database
    public void closedb(){
        this.close();
    }

    // insert regist on db
    public void insertreg(String vor, String str, String ema, String pas){
        ContentValues valors=new ContentValues();
        valors.put("Vorname",vor);
        valors.put("Straße",str);
        valors.put("Email",ema);
        valors.put("Passwort",pas);
        this.getWritableDatabase().insert("usersregist",null,valors);
    }

    // verify if the user exist on the database
    public Cursor verifyuserpass(String usu, String pas) throws SQLException{
        Cursor mcursor=null;
        mcursor=this.getReadableDatabase().query("usersregist",new String[]{"_ID","Vorname","Straße","Email","Passwort"},"Correo like '"+usu+"' and Password like '"+pas+"'",null,null,null,null);
        return mcursor;

    }


}

package com.xcore.xserver.link;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import OpenHelper.SQLite_OpenHelper;

public class Register extends AppCompatActivity {

    Button btnreginsert;
    EditText RegboxEmail, RegboxStraße, RegboxPasswort, RegboxVorname;

    SQLite_OpenHelper helper=new SQLite_OpenHelper(this,"ConfidentialDB",null,1);

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

        btnreginsert=(Button) findViewById(R.id.registdb);
        RegboxEmail=(EditText) findViewById(R.id.regbox_email);
        RegboxStraße=(EditText) findViewById(R.id.regbox_straße);
        RegboxPasswort=(EditText) findViewById(R.id.regbox_passwort);
        RegboxVorname=(EditText) findViewById(R.id.regbox_vorname);

        btnreginsert.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                helper.opendb();
                helper.insertreg(String.valueOf(RegboxVorname.getText()),
                        String.valueOf(RegboxStraße.getText()),
                        String.valueOf(RegboxEmail.getText()),
                        String.valueOf(RegboxPasswort.getText()));
                helper.closedb();

                Toast.makeText(getApplicationContext(),"Registrado Correctamente"
                        ,Toast.LENGTH_LONG).show();

                Intent i=new Intent(getApplicationContext(),MainActivity.class);
                startActivity(i);

            }
        });

    }
}

String[] parametros = {usu, pas};
Cursor cursor = db.rawQuery("SELECT * FROM usersregist WHERE Correo = ? AND
Password = ? ", parametros);