Welcome to my Android Content Provider tutorial. I’ve received many questions about this topic. I have received many questions specifically about how to access a Content Provider from another application. So here I’ll make to apps. One will function as the Content Provider and the other will access data using a Content Resolver.

I haven’t found a tutorial online that explains how easy it is to use Content Resolvers in this way, so I hope this video is very useful. All of the code follows the video below and it is heavily commented.

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Code From the Video

Contact Provider Code

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.newthinktank.derekbanas.contactprovider" >

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <!-- The Content Provider is declared -->
        <provider
            android:name=".ContactProvider"
            android:authorities="com.newthinktank.derekbanas.contactprovider.ContactProvider"
            android:exported="true"
            android:multiprocess="true" >
        </provider>

    </application>

</manifest>

ContactProvider.java

package com.newthinktank.derekbanas.contactprovider;

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Context;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.widget.Toast;

import java.util.HashMap;

// Contact Providers allow applications to share data using an API
// The interface provides access using delete, insert, query and update methods

public class ContactProvider extends ContentProvider{

    // The Java namespace for the Content Provider
    static final String PROVIDER_NAME = "com.newthinktank.derekbanas.contactprovider.ContactProvider";

    // Assigned to a content provider so any application can access it
    // cpcontacts is the virtual directory in the provider
    static final String URL = "content://" + PROVIDER_NAME + "/cpcontacts";
    static final Uri CONTENT_URL = Uri.parse(URL);

    static final String id = "id";
    static final String name = "name";
    static final int uriCode = 1;

    private static HashMap<String, String> values;

    // Used to match uris with Content Providers
    static final UriMatcher uriMatcher;

    static {
        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        uriMatcher.addURI(PROVIDER_NAME, "cpcontacts", uriCode);
    }

    private SQLiteDatabase sqlDB;
    static final String DATABASE_NAME = "myContacts";
    static final String TABLE_NAME = "names";
    static final int DATABASE_VERSION = 1;
    static final String CREATE_DB_TABLE = " CREATE TABLE " + TABLE_NAME
            + " (id INTEGER PRIMARY KEY AUTOINCREMENT, "
            + " name TEXT NOT NULL);";

    @Override
    public boolean onCreate() {
        DatabaseHelper dbHelper = new DatabaseHelper(getContext());
        sqlDB = dbHelper.getWritableDatabase();
        if (sqlDB != null) {
            return true;
        }
        return false;
    }

    // Returns a cursor that provides read and write access to the results of the query
    // Uri : Links to the table in the provider (The From part of a query)
    // projection : an array of columns to retrieve with each row
    // selection : The where part of the query selection
    // selectionArgs : The argument part of the where (where id = 1)
    // sortOrder : The order by part of the query
    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {

        // Used to create a SQL query
        SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();

        // Set table to query
        queryBuilder.setTables(TABLE_NAME);

        // Used to match uris with Content Providers
        switch (uriMatcher.match(uri)) {
            case uriCode:

                // A projection map maps from passed column names to database column names
                queryBuilder.setProjectionMap(values);
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }

        // Cursor provides read and write access to the database
        Cursor cursor = queryBuilder.query(sqlDB, projection, selection, selectionArgs, null,
                null, sortOrder);

        // Register to watch for URI changes
        cursor.setNotificationUri(getContext().getContentResolver(), uri);
        return cursor;
    }

    // Handles requests for the MIME type (Type of Data) of the data at the URI
    @Override
    public String getType(Uri uri) {

        // Used to match uris with Content Providers
        switch (uriMatcher.match(uri)) {

            // vnd.android.cursor.dir/cpcontacts states that we expect multiple pieces of data
            case uriCode:
                return "vnd.android.cursor.dir/cpcontacts";

            default:
                throw new IllegalArgumentException("Unsupported URI: " + uri);
        }
    }

    // Used to insert a new row into the provider
    // Receives the URI (Uniform Resource Identifier) for the Content Provider and a set of values
    @Override
    public Uri insert(Uri uri, ContentValues values) {

        // Gets the row id after inserting a map with the keys representing the the column
        // names and their values. The second attribute is used when you try to insert
        // an empty row
        long rowID = sqlDB.insert(TABLE_NAME, null, values);

        // Verify a row has been added
        if (rowID > 0) {

            // Append the given id to the path and return a Builder used to manipulate URI
            // references
            Uri _uri = ContentUris.withAppendedId(CONTENT_URL, rowID);

            // getContentResolver provides access to the content model
            // notifyChange notifies all observers that a row was updated
            getContext().getContentResolver().notifyChange(_uri, null);

            // Return the Builder used to manipulate the URI
            return _uri;
        }
        Toast.makeText(getContext(), "Row Insert Failed", Toast.LENGTH_LONG).show();
        return null;
    }

    // Deletes a row or a selection of rows
    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        int rowsDeleted = 0;

        // Used to match uris with Content Providers
        switch (uriMatcher.match(uri)) {
            case uriCode:
                rowsDeleted = sqlDB.delete(TABLE_NAME, selection, selectionArgs);
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }

        // getContentResolver provides access to the content model
        // notifyChange notifies all observers that a row was updated
        getContext().getContentResolver().notifyChange(uri, null);
        return rowsDeleted;
    }

    // Used to update a row or a selection of rows
    // Returns to number of rows updated
    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        int rowsUpdated = 0;

        // Used to match uris with Content Providers
        switch (uriMatcher.match(uri)) {
            case uriCode:

                // Update the row or rows of data
                rowsUpdated = sqlDB.update(TABLE_NAME, values, selection, selectionArgs);
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }

        // getContentResolver provides access to the content model
        // notifyChange notifies all observers that a row was updated
        getContext().getContentResolver().notifyChange(uri, null);
        return rowsUpdated;
    }

    // Creates and manages our database
    private static class DatabaseHelper extends SQLiteOpenHelper {
        DatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase sqlDB) {
            sqlDB.execSQL(CREATE_DB_TABLE);
        }

        // Recreates the table when the database needs to be upgraded
        @Override
        public void onUpgrade(SQLiteDatabase sqlDB, int oldVersion, int newVersion) {
            sqlDB.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
            onCreate(sqlDB);
        }
    }

}

MainActivity.java

package com.newthinktank.derekbanas.contactprovider;

import android.app.Activity;
import android.content.ContentValues;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;


public class MainActivity extends Activity {

    EditText contactNameEditText;

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

        contactNameEditText = (EditText) findViewById(R.id.contactNameEditText);
    }

    public void addName(View view) {

        // Get the name supplied
        String name = contactNameEditText.getText().toString();

        // Stores a key value pair
        ContentValues values = new ContentValues();
        values.put(ContactProvider.name, name);

        // Provides access to other applications Content Providers
        Uri uri = getContentResolver().insert(ContactProvider.CONTENT_URL, values);

        Toast.makeText(getBaseContext(), "New Contact Added", Toast.LENGTH_LONG)
                .show();
    }

}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/contactNameEditText"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:hint="Add Name" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/addContactButton"
        android:text="Add Name"
        android:onClick="addName"
        android:layout_below="@+id/contactNameEditText"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />

</RelativeLayout>

Get Contacts Code

MainActivity.java

package com.newthinktank.derekbanas.getcontacts;

import android.app.Activity;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.content.CursorLoader;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;


public class MainActivity extends Activity {

    // The URL used to target the content provider
    static final Uri CONTENT_URL =
            Uri.parse("content://com.newthinktank.derekbanas.contactprovider.ContactProvider/cpcontacts");

    TextView contactsTextView = null;
    EditText deleteIDEditText, idLookupEditText, addNameEditText;
    CursorLoader cursorLoader;

    // Provides access to other applications Content Providers
    ContentResolver resolver;

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

        resolver = getContentResolver();

        contactsTextView = (TextView) findViewById(R.id.contactsTextView);
        deleteIDEditText = (EditText) findViewById(R.id.deleteIDEditText);
        idLookupEditText = (EditText) findViewById(R.id.idLookupEditText);
        addNameEditText = (EditText) findViewById(R.id.addNameEditText);

        getContacts();

    }

    public void getContacts(){

        // Projection contains the columns we want
        String[] projection = new String[]{"id", "name"};

        // Pass the URL, projection and I'll cover the other options below
        Cursor cursor = resolver.query(CONTENT_URL, projection, null, null, null);

        String contactList = "";

        // Cycle through and display every row of data
        if(cursor.moveToFirst()){

            do{

                String id = cursor.getString(cursor.getColumnIndex("id"));
                String name = cursor.getString(cursor.getColumnIndex("name"));

                contactList = contactList + id + " : " + name + "\n";

            }while (cursor.moveToNext());

        }

        contactsTextView.setText(contactList);

    }

    public void deleteContact(View view) {

        String idToDelete = deleteIDEditText.getText().toString();

        // Use the resolver to delete ids by passing the content provider url
        // what you are targeting with the where and the string that replaces
        // the ? in the where clause
        long idDeleted = resolver.delete(CONTENT_URL,
                "id = ? ", new String[]{idToDelete});

        getContacts();

    }

    public void lookupContact(View view) {

        // The id we want to search for
        String idToFind = idLookupEditText.getText().toString();

        // Holds the column data we want to retrieve
        String[] projection = new String[]{"id", "name"};

        // Pass the URL for Content Provider, the projection,
        // the where clause followed by the matches in an array for the ?
        // null is for sort order
        Cursor cursor = resolver.query(CONTENT_URL,
                projection, "id = ? ", new String[]{idToFind}, null);

        String contact = "";

        // Cycle through our one result or print error
        if(cursor.moveToFirst()){

            String id = cursor.getString(cursor.getColumnIndex("id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));

            contact = contact + id + " : " + name + "\n";

        } else {

            Toast.makeText(this, "Contact Not Found", Toast.LENGTH_SHORT).show();

        }

        contactsTextView.setText(contact);

    }

    public void showContacts(View view) {

        getContacts();

    }

    public void addContact(View view) {

        // Get the name to add
        String nameToAdd = addNameEditText.getText().toString();

        // Put in the column name and the value
        ContentValues values = new ContentValues();
        values.put("name", nameToAdd);

        // Insert the value into the Content Provider
        resolver.insert(CONTENT_URL, values);

        getContacts();

    }
}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">


    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Show Contacts"
        android:id="@+id/btnRetrieve"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:onClick="showContacts"/>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Contacts"
        android:id="@+id/contactsTextView"
        android:ems="10"
        android:layout_centerVertical="true"
        android:layout_alignRight="@+id/findContactButton"
        android:layout_alignEnd="@+id/findContactButton" />

    <EditText
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:inputType="number"
        android:ems="10"
        android:id="@+id/deleteIDEditText"
        android:layout_below="@+id/btnRetrieve"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:hint="ID to Delete"
        android:layout_marginTop="10dp"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Delete ID"
        android:id="@+id/deleteIDButton"
        android:layout_below="@+id/btnRetrieve"
        android:layout_toRightOf="@+id/deleteIDEditText"
        android:layout_toEndOf="@+id/deleteIDEditText"
        android:layout_marginLeft="30dp"
        android:layout_marginStart="30dp"
        android:onClick="deleteContact"/>

    <EditText
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:inputType="number"
        android:ems="10"
        android:id="@+id/idLookupEditText"
        android:layout_below="@+id/deleteIDEditText"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:hint="ID to Find"
        android:layout_marginTop="10dp"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Find Contact"
        android:id="@+id/findContactButton"
        android:layout_below="@+id/deleteIDButton"
        android:layout_toRightOf="@+id/idLookupEditText"
        android:layout_toEndOf="@+id/idLookupEditText"
        android:layout_marginLeft="30dp"
        android:layout_marginStart="30dp"
        android:onClick="lookupContact"/>

    <EditText
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:ems="10"
        android:id="@+id/addNameEditText"
        android:layout_below="@+id/idLookupEditText"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:hint="Name to Add"
        android:layout_marginTop="10dp"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Add Contact"
        android:id="@+id/addContactButton"
        android:layout_below="@+id/findContactButton"
        android:layout_alignTop="@+id/addNameEditText"
        android:layout_toRightOf="@+id/addNameEditText"
        android:layout_toEndOf="@+id/addNameEditText"
        android:layout_marginLeft="30dp"
        android:layout_marginStart="30dp"
        android:onClick="addContact"/>
</RelativeLayout>