Part 1 – Layouts, Contract & SQLiteOpenHelper

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In this course we will use an SQLite database to build a grocery list app. We will save data into our database, display the results in a RecyclerView using a selfmade CursorAdapter and delete entries by swiping them off our list.

In the first video we will prepare the layouts and 2 helper classes for our database operations: the Contract class and the SQLiteOpenHelper class.

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Links & Dependenciesactivity_main.xmlgrocery_item.xmlGroceryContract.javaGroceryDBHelper.java

RecyclerView dependency:

developer.android.com/topic/libraries/support-library/packages.html#v7-recyclerview

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    tools:context="com.example.application.grocerylist.MainActivity">

    <EditText
        android:id="@+id/edittext_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/textview_amount"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/edittext_name"
        android:layout_centerHorizontal="true"
        android:layout_margin="8dp"
        android:text="0"
        android:textSize="50sp" />

    <Button
        android:id="@+id/button_decrease"
        android:layout_width="50dp"
        android:layout_height="wrap_content"
        android:layout_alignTop="@+id/textview_amount"
        android:layout_alignBottom="@+id/textview_amount"
        android:layout_toStartOf="@+id/textview_amount"
        android:text="-" />

    <Button
        android:id="@+id/button_increase"
        android:layout_width="50dp"
        android:layout_height="wrap_content"
        android:layout_alignTop="@+id/textview_amount"
        android:layout_alignBottom="@+id/textview_amount"
        android:layout_toEndOf="@+id/textview_amount"
        android:text="+" />

    <Button
        android:id="@+id/button_add"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignTop="@+id/button_increase"
        android:layout_alignBottom="@+id/button_increase"
        android:layout_marginStart="8dp"
        android:layout_toEndOf="@+id/button_increase"
        android:text="add" />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/textview_amount" />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="8dp">

    <TextView
        android:id="@+id/textview_amount_item"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="0"
        android:textSize="30sp" />

    <TextView
        android:id="@+id/textview_name_item"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="Empty Item"
        android:textSize="30sp" />

</LinearLayout>

package com.example.application.grocerylist;

import android.provider.BaseColumns;

public class GroceryContract {

    private GroceryContract() {
    }

    public static final class GroceryEntry implements BaseColumns {
        public static final String TABLE_NAME = "groceryList";
        public static final String COLUMN_NAME = "name";
        public static final String COLUMN_AMOUNT = "amount";
        public static final String COLUMN_TIMESTAMP = "timestamp";
    }
}

package com.example.application.grocerylist;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import com.example.application.grocerylist.GroceryContract.*;


public class GroceryDBHelper extends SQLiteOpenHelper {
    public static final String DATABASE_NAME = "grocerylist.db";
    public static final int DATABASE_VERSION = 1;

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

    @Override
    public void onCreate(SQLiteDatabase db) {
        final String SQL_CREATE_GROCERYLIST_TABLE = "CREATE TABLE " +
                GroceryEntry.TABLE_NAME + " (" +
                GroceryEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                GroceryEntry.COLUMN_NAME + " TEXT NOT NULL, " +
                GroceryEntry.COLUMN_AMOUNT + " INTEGER NOT NULL, " +
                GroceryEntry.COLUMN_TIMESTAMP + " TIMESTAMP DEFAULT CURRENT_TIMESTAMP" +
                ");";

        db.execSQL(SQL_CREATE_GROCERYLIST_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + GroceryEntry.TABLE_NAME);
        onCreate(db);
    }
}