Android SQLite - RecyclerView - CRUD then Swipe To Refresh Data


Android SQLite - RecyclerView - CRUD then Swipe To Refresh Data Tutorial
.

This is an android sqlite refresh tutorial with recyclerview as our adapterview.Users will swipe the recyclerview or pull it down thus refreshing data stored in sqlite database.

However first see how to perform CRUD adding data to sqlite database. Then we retrieve the data and bind to a RecyclerView.

Then when the user can show up an an input dialog and add more data. Those data don't get shown immediately.

He can then swipe down/ or pull down the RecyclerView to refresh the data.

We use the SwipeRefreshLayout to enable this swiping functionality.

In short this is what we do in this episode 10:

  1. INSERT data to SQLite database.
  2. SELECT data from our SQLite database.
  3. Reload/Refresh data from our SQLite database when the user swipes/pulls down our RecyclerView.

Project Demo

SwipeRefreshLayout was introduced in Android KitKat.

1. Create Basic Activity Project

First create an empty project in android studio.You can see how to do so here.

2. Add Dependencies

Lets add dependencies in our app level build.gradle:

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.3.0'
    compile 'com.android.support:design:23.3.0'
    compile 'com.android.support:cardview-v7:23.3.0'
}

3. Create User Interface

User interfaces are typically created in android using XML layouts as opposed by direct java coding.

Here are our layouts for this project:

(a). activity_main.xml
  • This layout gets inflated to MainActivity user interface.
  • It includes the content_main.xml.
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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:fitsSystemWindows="true"
    tools:context="com.tutorials.hp.sqliteswipetorefresh.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </android.support.design.widget.AppBarLayout>

    <include layout="@layout/content_main" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        android:src="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>
(b). content_main.xml

This layout gets included in your activity_main.xml.

We wrap our RecyclerView inside a SwipeRefreshLayout:

<?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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.tutorials.hp.sqliteswipetorefresh.MainActivity"
    tools:showIn="@layout/activity_main">

    <android.support.v4.widget.SwipeRefreshLayout
        android:id="@+id/swiper"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        ></android.support.v7.widget.RecyclerView>

    </android.support.v4.widget.SwipeRefreshLayout>

</RelativeLayout>
(c). dialog_input.xml

This is the input dialog.

Users will enter data to SQLite database via this dialog.

<?xml version="1.0" encoding="utf-8"?>

    <android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="horizontal" android:layout_width="500dp"
        xmlns:card_view="http://schemas.android.com/apk/res-auto"
        android:layout_margin="1dp"
        card_view:cardCornerRadius="10dp"
        card_view:cardElevation="5dp"

        android:layout_height="match_parent">

    <LinearLayout
            android:layout_width="match_parent"
            android:orientation="vertical"
            android:layout_height="match_parent">

        <android.support.design.widget.TextInputLayout
            android:id="@+id/nameLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <EditText
                android:id="@+id/nameEditTxt"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:singleLine="true"
                android:hint= "Name" />
        </android.support.design.widget.TextInputLayout>

        <Button android:id="@+id/saveBtn"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Save"
            android:clickable="true"
            android:background="@color/colorAccent"
            android:layout_marginTop="40dp"
            android:textColor="@android:color/white"/>
        <Button android:id="@+id/retrieveBtn"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Retrieve"
            android:clickable="true"
            android:background="@color/colorAccent"
            android:layout_marginTop="40dp"
            android:textColor="@android:color/white"/>
</LinearLayout>
    </android.support.v7.widget.CardView>
(d). model.xml

This is our model layout.

The RecyclerView viewitems will get inflated from this template. This will happpen in our RecyclerView Adapter class.

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:layout_margin="5dp"
    card_view:cardCornerRadius="10dp"
    card_view:cardElevation="5dp"
    android:layout_height="wrap_content">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceLarge"
            android:text="Name"
            android:id="@+id/nameTxt"
            android:padding="10dp"
            android:layout_alignParentTop="true"
            />

    </RelativeLayout>
</android.support.v7.widget.CardView>

4. Java Classes

Here are our Java Classes:

Our Data Object

(a) Spacecraft.java

This is our model class. It models a single spacecraft.

It's our POJO class.

package com.tutorials.hp.sqliteswipetorefresh.mDataObject;

public class SpaceCraft {

    String name;
    int id;

    public SpaceCraft() {
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }
}

Our SQLite Classes

(a) Constants.java

Our database constants.

Includes sqlite database name, table name, database version, table creation statement and table dropping statements as string constants.

package com.tutorials.hp.sqliteswipetorefresh.mDataBase;

public class Constants {
    //COLUMNS
    static final String ROW_ID="id";
    static final String NAME="name";

    //DB PROPS
    static final String DB_NAME="hh_DB";
    static final String TB_NAME="hh_TB";
    static final int DB_VERSION=1;

    //CREATE_TB
    static final String CREATE_TB="CREATE TABLE hh_TB(id INTEGER PRIMARY KEY AUTOINCREMENT,"
            + "name TEXT NOT NULL);";

    //DROP_TB
     static final String DROP_TB="DROP TABLE IF EXISTS "+TB_NAME;

}
(b) DBHelper.java

Our database helper class.

Creates sqlite database table and upgrades it.

package com.tutorials.hp.sqliteswipetorefresh.mDataBase;

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

public class DBHelper extends SQLiteOpenHelper {

    public DBHelper(Context context) {
        super(context, Constants.DB_NAME, null, Constants.DB_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        try
        {
            db.execSQL(Constants.CREATE_TB);
        }catch (SQLException e)
        {
            e.printStackTrace();
        }

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL(Constants.DROP_TB);
        onCreate(db);
    }
}
(c) DBAdapter.java

Our sqlite database adapter class.

Allows us perform our CRUD operations : opening database, inserting data, retrieving data, closing the database.

package com.tutorials.hp.sqliteswipetorefresh.mDataBase;

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

public class DBAdapter {

    Context c;
    SQLiteDatabase db;
    DBHelper helper;

    public DBAdapter(Context c) {
        this.c = c;
        helper=new DBHelper(c);
    }

    //OPEN DB
    public void openDB()
    {
        try
        {
            db=helper.getWritableDatabase();
        }catch (SQLException e)
        {
            e.printStackTrace();
        }
    }

    //CLOSING
    public void closeDB()
    {
        try
        {
            helper.close();

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

    //SAVE OR INSERTING
    public boolean add(String name)
    {
        try
        {
            ContentValues cv=new ContentValues();
            cv.put(Constants.NAME, name);

            db.insert(Constants.TB_NAME, Constants.ROW_ID, cv);

            return true;

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

        return false;
    }

    //SELECT OR RETRIEVE
    public Cursor retrieve()
    {
        String[] columns={Constants.ROW_ID,Constants.NAME};

        return db.query(Constants.TB_NAME,columns,null,null,null,null,null);
    }
}

Our RecyclerView Classes

(a) MyHolder.java

Our RecyclerView ViewHolder class.

package com.tutorials.hp.sqliteswipetorefresh.mRecycler;

import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;

import com.tutorials.hp.sqliteswipetorefresh.R;

public class MyHolder extends RecyclerView.ViewHolder {

    TextView nameTxt;

    public MyHolder(View itemView) {
        super(itemView);

        this.nameTxt= (TextView) itemView.findViewById(R.id.nameTxt);
    }
}

########(b) MyAdapter.java Our RecyclerView Adapter class.

package com.tutorials.hp.sqliteswipetorefresh.mRecycler;

import android.content.Context;
import android.database.Cursor;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.tutorials.hp.sqliteswipetorefresh.R;
import com.tutorials.hp.sqliteswipetorefresh.mDataBase.DBAdapter;
import com.tutorials.hp.sqliteswipetorefresh.mDataObject.SpaceCraft;

import java.util.ArrayList;

public class MyAdapter extends RecyclerView.Adapter<MyHolder> {

    Context c;
    ArrayList<SpaceCraft> spaceCrafts;
    SwipeRefreshLayout swipeRefreshLayout;

    public MyAdapter(Context c, ArrayList<SpaceCraft> spaceCrafts, SwipeRefreshLayout swipeRefreshLayout) {
        this.c = c;
        this.spaceCrafts = spaceCrafts;
        this.swipeRefreshLayout = swipeRefreshLayout;
    }

    @Override
    public MyHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v= LayoutInflater.from(parent.getContext()).inflate(R.layout.model,parent,false);
        MyHolder holder=new MyHolder(v);
        return holder;
    }

    @Override
    public void onBindViewHolder(MyHolder holder, int position) {
        holder.nameTxt.setText(spaceCrafts.get(position).getName());

        swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                getUpdates();
            }
        });

    }

    @Override
    public int getItemCount() {
        return spaceCrafts.size();
    }

    private void getUpdates()
    {
        spaceCrafts.clear();

        DBAdapter db=new DBAdapter(c);
        db.openDB();
        Cursor c=db.retrieve();

        while (c.moveToNext())
        {
            int id=c.getInt(0);
            String name=c.getString(1);

            SpaceCraft s=new SpaceCraft();
            s.setId(id);
            s.setName(name);

            spaceCrafts.add(s);
        }

        db.closeDB();

        swipeRefreshLayout.setRefreshing(false);
        this.notifyDataSetChanged();
    }
}

Our Activity class

(a) MainActivity.java

Our MainActivity class. Will display our RecyclerView and show us a dialog for adding data to SQLite database.

package com.tutorials.hp.sqliteswipetorefresh;

import android.app.Dialog;
import android.database.Cursor;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.tutorials.hp.sqliteswipetorefresh.mDataBase.DBAdapter;
import com.tutorials.hp.sqliteswipetorefresh.mDataObject.SpaceCraft;
import com.tutorials.hp.sqliteswipetorefresh.mRecycler.MyAdapter;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    RecyclerView rv;
    MyAdapter adapter;
    SwipeRefreshLayout swipeRefreshLayout;
    EditText nameEditText;
    Button saveBtn,retrieveBtn;
    ArrayList<SpaceCraft> spaceCrafts=new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);

        rv= (RecyclerView) findViewById(R.id.rv);
        rv.setLayoutManager(new LinearLayoutManager(this));

        swipeRefreshLayout= (SwipeRefreshLayout) findViewById(R.id.swiper);

        adapter=new MyAdapter(this,spaceCrafts,swipeRefreshLayout);

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                displayDialog();
            }
        });

    }

    private void displayDialog()
    {
        Dialog d=new Dialog(this);
        d.setTitle("Save To Database");
        d.setContentView(R.layout.dialog_layout);

        nameEditText= (EditText) d.findViewById(R.id.nameEditTxt);
        saveBtn= (Button) d.findViewById(R.id.saveBtn);
        retrieveBtn= (Button) d.findViewById(R.id.retrieveBtn);

        saveBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                save(nameEditText.getText().toString());

            }
        });
        retrieveBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                 getSpaceCrafts();
            }
        });

        d.show();
    }

    private void save(String name)
    {
        DBAdapter db=new DBAdapter(this);
        db.openDB();
        if(db.add(name))
        {
            nameEditText.setText("");
        }else {
            Toast.makeText(this,"Unable to save",Toast.LENGTH_SHORT).show();
        }

        db.closeDB();
    }

    private void getSpaceCrafts()
    {
        spaceCrafts.clear();

        DBAdapter db=new DBAdapter(this);
        db.openDB();
        Cursor c=db.retrieve();

        while (c.moveToNext())
        {
            int id=c.getInt(0);
            String name=c.getString(1);

            SpaceCraft s=new SpaceCraft();
            s.setId(id);
            s.setName(name);

            spaceCrafts.add(s);
        }

        db.closeDB();

        rv.setAdapter(adapter);
    }

}

Download

Download code below.

If you prefer more explanations or want to see the demo then the video tutorial is here.

No. Location Link
1. GitHub Direct Download)
2. GitHub Browse
3. YouTube Video Tutorial
4. YouTube Our YouTube Channel

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