1 page.title=Getting a Result from an Activity 2 parent.title=Interacting with Other Apps 3 parent.link=index.html 4 5 trainingnavtop=true 6 previous.title=Sending the User to Another App 7 previous.link=sending.html 8 next.title=Allowing Other Apps to Start Your Activity 9 next.link=filters.html 10 11 @jd:body 12 13 <div id="tb-wrapper"> 14 <div id="tb"> 15 16 <h2>This lesson teaches you to</h2> 17 <ol> 18 <li><a href="#StartActivity">Start the Activity</a></li> 19 <li><a href="#ReceiveResult">Receive the Result</a></li> 20 </ol> 21 22 <h2>You should also read</h2> 23 <ul> 24 <li><a href="{@docRoot}training/sharing/index.html">Sharing Content</a></li> 25 </ul> 26 27 </div> 28 </div> 29 30 <p>Starting another activity doesn't have to be one-way. You can also start another activity and 31 receive a result back. To receive a result, call {@link android.app.Activity#startActivityForResult 32 startActivityForResult()} (instead of {@link android.app.Activity#startActivity 33 startActivity()}).</p> 34 35 <p>For example, your app can start a camera app and receive the captured photo as a result. Or, you 36 might start the People app in order for the user to select a 37 contact and you'll receive the contact details as a result.</p> 38 39 <p>Of course, the activity that responds must be designed to return a result. When it does, it 40 sends the result as another {@link android.content.Intent} object. Your activity receives it in 41 the {@link android.app.Activity#onActivityResult onActivityResult()} callback.</p> 42 43 <p class="note"><strong>Note:</strong> You can use explicit or implicit intents when you call 44 {@link android.app.Activity#startActivityForResult startActivityForResult()}. When starting one of 45 your own activities to receive a result, you should use an explicit intent to ensure that you 46 receive the expected result.</p> 47 48 49 <h2 id="StartActivity">Start the Activity</h2> 50 51 <p>There's nothing special about the {@link android.content.Intent} object you use when starting 52 an activity for a result, but you do need to pass an additional integer argument to the {@link 53 android.app.Activity#startActivityForResult startActivityForResult()} method.</p> 54 55 <p>The integer argument is a "request code" that identifies your request. When you receive the 56 result {@link android.content.Intent}, the callback provides the same request code so that your 57 app can properly identify the result and determine how to handle it.</p> 58 59 <p>For example, here's how to start an activity that allows the user to pick a contact:</p> 60 61 <pre> 62 static final int PICK_CONTACT_REQUEST = 1; // The request code 63 ... 64 private void pickContact() { 65 Intent pickContactIntent = new Intent(Intent.ACTION_PICK, new Uri("content://contacts")); 66 pickContactIntent.setType(Phone.CONTENT_TYPE); // Show user only contacts w/ phone numbers 67 startActivityForResult(pickContactIntent, PICK_CONTACT_REQUEST); 68 } 69 </pre> 70 71 72 <h2 id="ReceiveResult">Receive the Result</h2> 73 74 <p>When the user is done with the subsequent activity and returns, the system calls your activity's 75 {@link android.app.Activity#onActivityResult onActivityResult()} method. This method includes three 76 arguments:</p> 77 78 <ul> 79 <li>The request code you passed to {@link 80 android.app.Activity#startActivityForResult startActivityForResult()}.</li> 81 <li>A result code specified by the second activity. This is either {@link 82 android.app.Activity#RESULT_OK} if the operation was successful or {@link 83 android.app.Activity#RESULT_CANCELED} if the user backed out or the operation failed for some 84 reason.</li> 85 <li>An {@link android.content.Intent} that carries the result data.</li> 86 </ul> 87 88 <p>For example, here's how you can handle the result for the "pick a contact" intent:</p> 89 90 <pre> 91 @Override 92 protected void onActivityResult(int requestCode, int resultCode, Intent data) { 93 // Check which request we're responding to 94 if (requestCode == PICK_CONTACT_REQUEST) { 95 // Make sure the request was successful 96 if (resultCode == RESULT_OK) { 97 // The user picked a contact. 98 // The Intent's data Uri identifies which contact was selected. 99 100 // Do something with the contact here (bigger example below) 101 } 102 } 103 } 104 </pre> 105 106 <p>In this example, the result {@link android.content.Intent} returned by 107 Android's Contacts or People app provides a content {@link android.net.Uri} that identifies the 108 contact the user selected.</p> 109 110 <p>In order to successfully handle the result, you must understand what the format of the result 111 {@link android.content.Intent} will be. Doing so is easy when the activity returning a result is 112 one of your own activities. Apps included with the Android platform offer their own APIs that 113 you can count on for specific result data. For instance, the People app (Contacts app on some older 114 versions) always returns a result with the content URI that identifies the selected contact, and the 115 Camera app returns a {@link android.graphics.Bitmap} in the {@code "data"} extra (see the class 116 about <a href="{@docRoot}training/camera/index.html">Capturing Photos</a>).</p> 117 118 119 <h4>Bonus: Read the contact data</h4> 120 121 <p>The code above showing how to get a result from the People app doesn't go into 122 details about how to actually read the data from the result, because it requires more advanced 123 discussion about <a href="{@docRoot}guide/topics/providers/content-providers.html">content 124 providers</a>. However, if you're curious, here's some more code that shows how to query the 125 result data to get the phone number from the selected contact:</p> 126 127 <pre> 128 @Override 129 protected void onActivityResult(int requestCode, int resultCode, Intent data) { 130 // Check which request it is that we're responding to 131 if (requestCode == PICK_CONTACT_REQUEST) { 132 // Make sure the request was successful 133 if (resultCode == RESULT_OK) { 134 // Get the URI that points to the selected contact 135 Uri contactUri = data.getData(); 136 // We only need the NUMBER column, because there will be only one row in the result 137 String[] projection = {Phone.NUMBER}; 138 139 // Perform the query on the contact to get the NUMBER column 140 // We don't need a selection or sort order (there's only one result for the given URI) 141 // CAUTION: The query() method should be called from a separate thread to avoid blocking 142 // your app's UI thread. (For simplicity of the sample, this code doesn't do that.) 143 // Consider using {@link android.content.CursorLoader} to perform the query. 144 Cursor cursor = getContentResolver() 145 .query(contactUri, projection, null, null, null); 146 cursor.moveToFirst(); 147 148 // Retrieve the phone number from the NUMBER column 149 int column = cursor.getColumnIndex(Phone.NUMBER); 150 String number = cursor.getString(column); 151 152 // Do something with the phone number... 153 } 154 } 155 } 156 </pre> 157 158 <p class="note"><strong>Note:</strong> Before Android 2.3 (API level 9), performing a query 159 on the {@link android.provider.ContactsContract.Contacts Contacts Provider} (like the one shown 160 above) requires that your app declare the {@link 161 android.Manifest.permission#READ_CONTACTS} permission (see <a 162 href="{@docRoot}guide/topics/security/security.html">Security and Permissions</a>). However, 163 beginning with Android 2.3, the Contacts/People app grants your app a temporary 164 permission to read from the Contacts Provider when it returns you a result. The temporary permission 165 applies only to the specific contact requested, so you cannot query a contact other than the one 166 specified by the intent's {@link android.net.Uri}, unless you do declare the {@link 167 android.Manifest.permission#READ_CONTACTS} permission.</p> 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183
