Read Data with SQLite in Android


Create new project in Android Studio with steps as below:




Create new package named entities. In this package, create new java class named Contact.java as below:

package android.demo.entities;

import java.io.Serializable;

public class Contact implements Serializable {

    private int id;
    private String name;
    private String phone;
    private String address;
    private String email;
    private String description;

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getAddress() {
        return this.address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getEmail() {
        return this.email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getDescription() {
        return this.description;
    }

    public void setDescription(String description) {
        this.description = description;
    }
}

Create new package named database. In this package, create new java class named DatabaseHelper.java as below:

package android.demo.database;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.demo.entities.Contact;

import java.util.ArrayList;
import java.util.List;

public class DatabaseHelper extends SQLiteOpenHelper {

    private static String dbName = "ContactDB";
    private static int dbVersion = 1;

    private static String contactTable = "contact";

    private static String idColumn = "id";
    private static String nameColumn = "name";
    private static String phoneColumn = "phone";
    private static String addressColumn = "address";
    private static String emailColumn = "email";
    private static String descriptionColumn = "description";

    public DatabaseHelper(Context context) {
        super(context, dbName, null, dbVersion);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {

        sqLiteDatabase.execSQL("create table " + contactTable + "(" +
                    idColumn + " integer primary key autoincrement, " +
                    nameColumn + " tex, " +
                    phoneColumn + " text, " +
                    addressColumn + " text, " +
                    emailColumn + " text, " +
                    descriptionColumn + " text " +
                ")"
        );

    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
        sqLiteDatabase.execSQL("drop table if exists " + contactTable);
        onCreate(sqLiteDatabase);
    }

    public List<Contact> findAll() {
        List<Contact> contacts = null;
        try {
            SQLiteDatabase sqLiteDatabase = getReadableDatabase();
            Cursor cursor = sqLiteDatabase.rawQuery("select * from " + contactTable, null);
            if (cursor.moveToFirst()) {
                contacts = new ArrayList<Contact>();
                do {
                    Contact contact = new Contact();
                    contact.setId(cursor.getInt(0));
                    contact.setName(cursor.getString(1));
                    contact.setPhone(cursor.getString(2));
                    contact.setAddress(cursor.getString(3));
                    contact.setEmail(cursor.getString(4));
                    contact.setDescription(cursor.getString(5));
                    contacts.add(contact);
                } while (cursor.moveToNext());
            }
        } catch (Exception e) {
            contacts = null;
        }
        return contacts;
    }

}




Select res\layout folder. In this folder, create new layout named contact_list_layout.xml as below:

<?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="match_parent"
    android:orientation="vertical">

    <TextView
        android:id="@+id/textViewName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/textViewPhone"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/textViewEmail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/textViewId"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:visibility="gone" />

</LinearLayout>

Create new package named adapters. In this package, create new java class named ContactListAdapter.java as below:

package android.demo.adapters;

import android.content.Context;
import android.demo.entities.Contact;
import android.demo.learnandroidwithrealapps.R;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.util.List;

public class ContactListAdapter extends ArrayAdapter<Contact> {

    private Context context;
    private List<Contact> contacts;

    public ContactListAdapter(Context context, List<Contact> contacts) {
        super(context, R.layout.contact_list_layout, contacts);
        this.context = context;
        this.contacts = contacts;
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View view, @NonNull ViewGroup parent) {
        ViewHolder viewHolder;
        if (view == null) {
            viewHolder = new ViewHolder();
            view = LayoutInflater.from(context).inflate(R.layout.contact_list_layout, null);
            viewHolder.textViewId = view.findViewById(R.id.textViewId);
            viewHolder.textViewName = view.findViewById(R.id.textViewName);
            viewHolder.textViewPhone = view.findViewById(R.id.textViewPhone);
            viewHolder.textViewEmail = view.findViewById(R.id.textViewEmail);
            view.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) view.getTag();
        }
        Contact contact = contacts.get(position);
        viewHolder.textViewId.setText(String.valueOf(contact.getId()));
        viewHolder.textViewName.setText(contact.getName());
        viewHolder.textViewPhone.setText(contact.getPhone());
        viewHolder.textViewEmail.setText(contact.getEmail());
        return view;
    }

    private static class ViewHolder {
        public static TextView textViewId;
        public static TextView textViewName;
        public static TextView textViewPhone;
        public static TextView textViewEmail;
    }

}

Open res\layout\activity_main.xml file and create layout as below:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">

    <ListView
        android:id="@+id/listViewContact"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>




Add code to MainActivity.java in android.demo.learnandroidwithrealapps package as below:

package android.demo.learnandroidwithrealapps;

import android.content.Intent;
import android.demo.adapters.ContactListAdapter;
import android.demo.database.DatabaseHelper;
import android.demo.entities.Contact;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.ListView;

import java.util.List;

public class MainActivity extends AppCompatActivity {

    private ListView listViewContact;

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

    private void initView() {
        listViewContact = findViewById(R.id.listViewContact);
    }

    private void loadData() {
        DatabaseHelper databaseHelper = new DatabaseHelper(getApplicationContext());
        List<Contact> contacts = databaseHelper.findAll();
        if (contacts != null) {
            listViewContact.setAdapter(new ContactListAdapter(getApplicationContext(), contacts));
        }
    }

}