A sample application that demonstrates use of legacy and current contacts APIs.

The application provides two implementations for access to contacts, one based
on legacy API, the other based on the current API.  The correct implementation
is chosen at runtime based on the version of the SDK.

Change-Id: Iae0bc8564be420ff504a5dc760b935630a7664e6

samples/BusinessCard/src/com/example/android/businesscard/BusinessCardActivity.java

@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.businesscard;
+
+import android.app.Activity;
+import android.content.Intent;
+import android.net.Uri;
+import android.os.AsyncTask;
+import android.os.Bundle;
+import android.view.View;
+import android.view.View.OnClickListener;
+import android.widget.Button;
+import android.widget.TextView;
+
+/**
+ * A simple activity that shows a "Pick Contact" button and two fields: contact's name
+ * and phone number.  The user taps on the Pick Contact button to bring up
+ * the contact chooser.  Once this activity receives the result from contact picker,
+ * it launches an asynchronous query (queries should always be asynchronous) to load
+ * contact's name and phone number. When the query completes, the activity displays
+ * the loaded data.
+ */
+public class BusinessCardActivity extends Activity  {
+
+    // Request code for the contact picker activity
+    private static final int PICK_CONTACT_REQUEST = 1;
+
+    /**
+     * An SDK-specific instance of {@link ContactAccessor}.  The activity does not need
+     * to know what SDK it is running in: all idiosyncrasies of different SDKs are
+     * encapsulated in the implementations of the ContactAccessor class.
+     */
+    private final ContactAccessor mContactAccessor = ContactAccessor.getInstance();
+
+    /**
+     * Called with the activity is first created.
+     */
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        setContentView(R.layout.business_card);
+
+        // Install a click handler on the Pick Contact button
+        Button pickContact = (Button)findViewById(R.id.pick_contact_button);
+        pickContact.setOnClickListener(new OnClickListener() {
+
+            public void onClick(View v) {
+                pickContact();
+            }
+        });
+    }
+
+    /**
+     * Click handler for the Pick Contact button.  Invokes a contact picker activity.
+     * The specific intent used to bring up that activity differs between versions
+     * of the SDK, which is why we delegate the creation of the intent to ContactAccessor.
+     */
+    protected void pickContact() {
+        startActivityForResult(mContactAccessor.getPickContactIntent(), PICK_CONTACT_REQUEST);
+    }
+
+    /**
+     * Invoked when the contact picker activity is finished. The {@code contactUri} parameter
+     * will contain a reference to the contact selected by the user. We will treat it as
+     * an opaque URI and allow the SDK-specific ContactAccessor to handle the URI accordingly.
+     */
+    @Override
+    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
+        if (requestCode == PICK_CONTACT_REQUEST && resultCode == RESULT_OK) {
+            loadContactInfo(data.getData());
+        }
+    }
+
+    /**
+     * Load contact information on a background thread.
+     */
+    private void loadContactInfo(Uri contactUri) {
+
+        /*
+         * We should always run database queries on a background thread. The database may be
+         * locked by some process for a long time.  If we locked up the UI thread while waiting
+         * for the query to come back, we might get an "Application Not Responding" dialog.
+         */
+        AsyncTask<Uri, Void, ContactInfo> task = new AsyncTask<Uri, Void, ContactInfo>() {
+
+            @Override
+            protected ContactInfo doInBackground(Uri... uris) {
+                return mContactAccessor.loadContact(getContentResolver(), uris[0]);
+            }
+
+            @Override
+            protected void onPostExecute(ContactInfo result) {
+                bindView(result);
+            }
+        };
+
+        task.execute(contactUri);
+    }
+
+    /**
+     * Displays contact information: name and phone number.
+     */
+    protected void bindView(ContactInfo contactInfo) {
+        TextView displayNameView = (TextView) findViewById(R.id.display_name_text_view);
+        displayNameView.setText(contactInfo.getDisplayName());
+
+        TextView phoneNumberView = (TextView) findViewById(R.id.phone_number_text_view);
+        phoneNumberView.setText(contactInfo.getPhoneNumber());
+    }
+}