How to Make Android Apps 21
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
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<?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
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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
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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
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<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
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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
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<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> |
Are you still considering a Unity series ?
Yes I’ll start with Open GL and libgdx first
Dude ur a very great guy.. Please make live wallpaper for android please teach us.. Others are asking money for softwares please help! God bless u
Thank you 🙂 I’ll make a wallpaper very soon. May God bless you as well.
I get the libGDX but why not Unity and what IDE would you use?
Actually I’ll first show how to create a framework for games so that they are completely understandable. I’ll then work my way up through the other frameworks.