PDM2 2020-11-19

package com.joythis.android.mycaller;

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;

import androidx.annotation.Nullable;

import java.util.ArrayList;

public class ContactDB extends SQLiteOpenHelper {
    public final static int CONTACTS_DB_VERSION = 1;
    public final static String CONTACTS_DB_NAME = "CONTACTS.DB";

    public final static String TABLE_CONTACTS = "tContacts";

    public final static String COL_ID = "_id";
    public final static String COL_NAME = "cName";
    public final static String COL_NUMBER = "cNumber";

    public final static String DROP_CONTACTS =
        "DROP TABLE IF EXISTS "+TABLE_CONTACTS+";";

    /*
    create table if not exists tContacts(
        _id integer primary key autoincrement,
        cName text not null,
        cNumber text not null
    );
     */
    public final static String CREATE_TABLE_CONTACTS =
        "CREATE TABLE IF NOT EXISTS "+
        TABLE_CONTACTS+"(\n"+
        COL_ID+" INTEGER PRIMARY KEY AUTOINCREMENT,\n"+
        COL_NAME+" TEXT NOT NULL,\n"+
        COL_NUMBER+" TEXT NOT NULL\n"+
        ");\n";

    public ContactDB(
        @Nullable Context context
    )
    {
        super(
            context,
            CONTACTS_DB_NAME,
            null,
            CONTACTS_DB_VERSION
        );
    }//ContactDB

    public ContactDB(
        @Nullable Context context,
        @Nullable String name,
        @Nullable SQLiteDatabase.CursorFactory factory,
        int version
    )
    {
        super(context, name, factory, version);
    }//ContactDB

    /*
    this method will install the necessary
    infrastructure (create the table(s))

    this method will be AUTOMATICALLY called by the
    framework upon the 1st need to read or write data
    in "Contact" related table(s)
     */
    @Override
    public void onCreate(SQLiteDatabase db) {
        installDB(db);
    }//onCreate

    /*
    will be automatically called whenever the database
    version changes
     */
    @Override
    public void onUpgrade
    (SQLiteDatabase db, int oldVersion, int newVersion)
    {
        try {
            if (newVersion > oldVersion) {
                db.execSQL(DROP_CONTACTS);
            }
        }
        catch(Exception e){
            Log.e(
               getClass().getName(),
               e.toString()
            );
        }

        installDB(db);
    }//onUpgrade

    void installDB(SQLiteDatabase pDB){
        if (pDB!=null){
            try {
                pDB.execSQL(CREATE_TABLE_CONTACTS);
            }
            catch(Exception e){
                Log.e(
                    getClass().getName(),
                    e.toString()
                );
            }
        }//if
    }//installDB

    public long insertContact (Contact pC){
        int iRet = -1;

        SQLiteDatabase db = this.getWritableDatabase();

        if (db!=null){
            String strName = pC.getmName();
            String strNumber = pC.getmNumber();

            ContentValues pairsCV = new ContentValues();
            pairsCV.put(COL_NAME, strName);
            pairsCV.put(COL_NUMBER, strNumber);

            //-1 on insert failure
            long idOfTheNewlyInsertedRecord = db.insert(
                TABLE_CONTACTS,
                null,
                pairsCV
            );

            db.close();
            return idOfTheNewlyInsertedRecord;

        }//if

        return iRet;
    }//insertContact

    public ArrayList<Contact> selectAll (){
        ArrayList<Contact> aRet = new ArrayList<Contact>();

        SQLiteDatabase db = this.getReadableDatabase();

        if (db!=null){
            //  " ORDER BY "+COL_ID +" DESC" ???
            String strQueryForSelect =
            "SELECT * FROM "+TABLE_CONTACTS+";";

            Cursor cursor = db.rawQuery(
                strQueryForSelect,
                null
            );

            if (cursor!=null){
                cursor.moveToFirst();
                while(!cursor.isAfterLast()){
                    int idxOfId = cursor.getColumnIndex(COL_ID); //0
                    int _id = cursor.getInt(idxOfId);

                    int idxOfName = cursor.getColumnIndex(COL_NAME);//1
                    String strName = cursor.getString(idxOfName);

                    //String strName = cursor.getString(1);

                    int idxOfNumber = cursor.getColumnIndex(COL_NUMBER); //2
                    String strNumber = cursor.getString(2);

                    Contact c = new Contact(
                        strName,
                        strNumber
                    );

                    aRet.add(c);

                    cursor.moveToNext();
                }//while there are records to be read and included in the return
            }//if there is a cursor objeto to navigate through the objects that the select returned
        }//if we got a readable database

        return aRet;
    }//selectAll
}//ContactDB

//**

package com.joythis.android.mycaller;

public class Contact {
    private String mName;
    private String mNumber;

    public String getmName() {
        return mName;
    }

    public String getmNumber() {
        return mNumber;
    }

    public Contact
    (
        String pName,
        String pNumber
    ){
        this.mName = pName;
        this.mNumber = pNumber;
    }//Contact

    public String toString(){
        String strRet = "";

        String.format(
            "%s : %s",
            this.mName,
            this.mNumber
        );

        return strRet;
    }//toString
}//Contact

//**

package com.joythis.android.mycaller;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    //data member to enable access to database operations
    //such as insert and select
    ContactDB mContactDB;
    Context mContext;

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

        init();
    }//onCreate

    void init(){
        mContactDB = new ContactDB(mContext);

        /*
        mContactDB.insertContact(new Contact("Artur", "123"));
        ArrayList<Contact> all = mContactDB.selectAllContacts();
         */
    }//init
}//MainActivity

//**

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

    <LinearLayout
        android:orientation="horizontal"
        android:id="@+id/LlContact"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <EditText
            android:hint="@string/strEtContactNameHint"
            android:id="@+id/idEtContactName"
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>

        <EditText
            android:hint="@string/strEtContactNumberHint"
            android:id="@+id/idEtContactNumber"
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>

    </LinearLayout>

    <Button
        android:layout_below="@id/LlContact"
        android:id="@+id/idBtnInsertContact"
        android:text="@string/strBtnInsertContact"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <ListView
        android:layout_below="@id/idBtnInsertContact"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</RelativeLayout>

//**

package com.joythis.android.mycaller;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    //data member to enable access to database operations
    //such as insert and select
    ContactDB mContactDB;
    Context mContext;

    EditText mEtContactName, mEtContactNumber;
    Button mBtnInsertContact;
    ListView mLvContacts;
    ArrayList<Contact> mAlContacts;
    ArrayAdapter<Contact> mAd;

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

        init();
    }//onCreate

    void init(){
        mContext = this;
        mEtContactName = findViewById(R.id.idEtContactName);
        mEtContactNumber = findViewById(R.id.idEtContactNumber);
        mBtnInsertContact = findViewById(R.id.idBtnInsertContact);
        mLvContacts = findViewById(R.id.idLvContacts);

        mAlContacts = new ArrayList<>();

        mContactDB = new ContactDB(mContext);
        syncLvContactsWithDB();

        mAd = new ArrayAdapter<>(
            mContext,
            android.R.layout.simple_list_item_1,
            mAlContacts
        );
        mLvContacts.setAdapter(mAd);

        /*
        mContactDB.insertContact(new Contact("Artur", "123"));
        ArrayList<Contact> all = mContactDB.selectAll();

         */
    }//init

    void syncLvContactsWithDB(){
        ArrayList<Contact> alTemp = mContactDB.selectAll();
        if (alTemp!=null && alTemp.size()>0){
            mAlContacts.clear();
            for (Contact c : alTemp){
                mAlContacts.add(c);
            }//for
            mAd.notifyDataSetChanged();
        }//if
    }//syncLvContactsWithDB
}