Getting Sqlite Database Poll Exception in Android

I'm working on a online application project. My application is working properly but sometime app is crashing and showing database pool exception in logcat when i'm trying to get data from server and calling my sqlite database function (Not all time. it's happening a very few time) . There are my answer regarding android database pool exception in stackoverflow. Most answer was like this "delete all db.close". After using this method now i'm getting less app crash. But problem is still there. Please check my database code and let me know if you found any problem. Thanks in advance. Sorry for bad English.

package com.example.helper;

import java.util.HashMap;

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

public class SQLiteHandler extends SQLiteOpenHelper {

    private static final String TAG = SQLiteHandler.class.getSimpleName();

    // All Static variables
    // Database Version
    private static final int DATABASE_VERSION = 1;

    // Database Name
    private static final String DATABASE_NAME = "android_api";

    // Login table name
    private static final String TABLE_LOGIN = "login";

    // Login Table Columns names
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    private static final String KEY_EMAIL = "email";
    private static final String KEY_CREATED_AT = "created_at";

    public SQLiteHandler(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    // Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_LOGIN_TABLE = "CREATE TABLE " + TABLE_LOGIN + "("
                + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
                + KEY_EMAIL + " TEXT UNIQUE,"
                + KEY_CREATED_AT + " TEXT" + ")";
        db.execSQL(CREATE_LOGIN_TABLE);
        Log.d(TAG, "Database tables created");
    }

    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_LOGIN);
        // Create tables again
        onCreate(db);
    }

    /**
     * Storing user details in database
     * */
    public void addUser(int uid,String name, String email) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_ID,uid);
        values.put(KEY_NAME, name); // Name
        values.put(KEY_EMAIL, email);
        // Email
        // Inserting Row
        long id = db.insert(TABLE_LOGIN, null, values);
        Log.d(TAG, "New user inserted into sqlite: " + id);
    }

    /**
     * Getting user data from database
     * */
    public HashMap<String, String> getUserDetails() {
        HashMap<String, String> user = new HashMap<String, String>();
        String selectQuery = "SELECT  * FROM " + TABLE_LOGIN;

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);
        // Move to first row
        cursor.moveToFirst();
        if (cursor.getCount() > 0) {
            user.put("name", cursor.getString(1));
            user.put("email", cursor.getString(2));
            user.put("created_at", cursor.getString(3));
        }
        cursor.close();
        // return user
        Log.d(TAG, "Fetching user from Sqlite: " + user.toString());

        return user;
    }

    public HashMap<String, Integer> getUid() {

            HashMap<String, Integer> uid = new HashMap<String,Integer>();
            String selectQuery = "SELECT  * FROM " + TABLE_LOGIN;
            SQLiteDatabase db = this.getReadableDatabase();
            Cursor cursor = db.rawQuery(selectQuery, null);
            // Move to first row
            cursor.moveToFirst();
            Log.d("database", "before uid put");
            if (cursor.getCount() > 0) {
                uid.put("uid",cursor.getInt(0));
            }
            cursor.close();
            // return user

            return uid;
    }

    /**
     * Re crate database Delete all tables and create them again
     * */
    public void deleteUsers() {
        SQLiteDatabase db = this.getWritableDatabase();
        // Delete All Rows
        db.delete(TABLE_LOGIN, null, null);

        Log.d(TAG, "Deleted all user info from sqlite");
    }

}