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 Simple Data</a></li> 25 <li><a href="{@docRoot}training/secure-file-sharing/index.html">Sharing Files</a> 26 </ul> 27 28 </div> 29 </div> 30 31 <p>Starting another activity doesn't have to be one-way. You can also start another activity and 32 receive a result back. To receive a result, call {@link android.app.Activity#startActivityForResult 33 startActivityForResult()} (instead of {@link android.app.Activity#startActivity 34 startActivity()}).</p> 35 36 <p>For example, your app can start a camera app and receive the captured photo as a result. Or, you 37 might start the People app in order for the user to select a 38 contact and you'll receive the contact details as a result.</p> 39 40 <p>Of course, the activity that responds must be designed to return a result. When it does, it 41 sends the result as another {@link android.content.Intent} object. Your activity receives it in 42 the {@link android.app.Activity#onActivityResult onActivityResult()} callback.</p> 43 44 <p class="note"><strong>Note:</strong> You can use explicit or implicit intents when you call 45 {@link android.app.Activity#startActivityForResult startActivityForResult()}. When starting one of 46 your own activities to receive a result, you should use an explicit intent to ensure that you 47 receive the expected result.</p> 48 49 50 <h2 id="StartActivity">Start the Activity</h2> 51 52 <p>There's nothing special about the {@link android.content.Intent} object you use when starting 53 an activity for a result, but you do need to pass an additional integer argument to the {@link 54 android.app.Activity#startActivityForResult startActivityForResult()} method.</p> 55 56 <p>The integer argument is a "request code" that identifies your request. When you receive the 57 result {@link android.content.Intent}, the callback provides the same request code so that your 58 app can properly identify the result and determine how to handle it.</p> 59 60 <p>For example, here's how to start an activity that allows the user to pick a contact:</p> 61 62 <pre> 63 static final int PICK_CONTACT_REQUEST = 1; // The request code 64 ... 65 private void pickContact() { 66 Intent pickContactIntent = new Intent(Intent.ACTION_PICK, Uri.parse("content://contacts")); 67 pickContactIntent.setType(Phone.CONTENT_TYPE); // Show user only contacts w/ phone numbers 68 startActivityForResult(pickContactIntent, PICK_CONTACT_REQUEST); 69 } 70 </pre> 71 72 73 <h2 id="ReceiveResult">Receive the Result</h2> 74 75 <p>When the user is done with the subsequent activity and returns, the system calls your activity's 76 {@link android.app.Activity#onActivityResult onActivityResult()} method. This method includes three 77 arguments:</p> 78 79 <ul> 80 <li>The request code you passed to {@link 81 android.app.Activity#startActivityForResult startActivityForResult()}.</li> 82 <li>A result code specified by the second activity. This is either {@link 83 android.app.Activity#RESULT_OK} if the operation was successful or {@link 84 android.app.Activity#RESULT_CANCELED} if the user backed out or the operation failed for some 85 reason.</li> 86 <li>An {@link android.content.Intent} that carries the result data.</li> 87 </ul> 88 89 <p>For example, here's how you can handle the result for the "pick a contact" intent:</p> 90 91 <pre> 92 @Override 93 protected void onActivityResult(int requestCode, int resultCode, Intent data) { 94 // Check which request we're responding to 95 if (requestCode == PICK_CONTACT_REQUEST) { 96 // Make sure the request was successful 97 if (resultCode == RESULT_OK) { 98 // The user picked a contact. 99 // The Intent's data Uri identifies which contact was selected. 100 101 // Do something with the contact here (bigger example below) 102 } 103 } 104 } 105 </pre> 106 107 <p>In this example, the result {@link android.content.Intent} returned by 108 Android's Contacts or People app provides a content {@link android.net.Uri} that identifies the 109 contact the user selected.</p> 110 111 <p>In order to successfully handle the result, you must understand what the format of the result 112 {@link android.content.Intent} will be. Doing so is easy when the activity returning a result is 113 one of your own activities. Apps included with the Android platform offer their own APIs that 114 you can count on for specific result data. For instance, the People app (Contacts app on some older 115 versions) always returns a result with the content URI that identifies the selected contact, and the 116 Camera app returns a {@link android.graphics.Bitmap} in the {@code "data"} extra (see the class 117 about <a href="{@docRoot}training/camera/index.html">Capturing Photos</a>).</p> 118 119 120 <h4>Bonus: Read the contact data</h4> 121 122 <p>The code above showing how to get a result from the People app doesn't go into 123 details about how to actually read the data from the result, because it requires more advanced 124 discussion about <a href="{@docRoot}guide/topics/providers/content-providers.html">content 125 providers</a>. However, if you're curious, here's some more code that shows how to query the 126 result data to get the phone number from the selected contact:</p> 127 128 <pre> 129 @Override 130 protected void onActivityResult(int requestCode, int resultCode, Intent data) { 131 // Check which request it is that we're responding to 132 if (requestCode == PICK_CONTACT_REQUEST) { 133 // Make sure the request was successful 134 if (resultCode == RESULT_OK) { 135 // Get the URI that points to the selected contact 136 Uri contactUri = data.getData(); 137 // We only need the NUMBER column, because there will be only one row in the result 138 String[] projection = {Phone.NUMBER}; 139 140 // Perform the query on the contact to get the NUMBER column 141 // We don't need a selection or sort order (there's only one result for the given URI) 142 // CAUTION: The query() method should be called from a separate thread to avoid blocking 143 // your app's UI thread. (For simplicity of the sample, this code doesn't do that.) 144 // Consider using {@link android.content.CursorLoader} to perform the query. 145 Cursor cursor = getContentResolver() 146 .query(contactUri, projection, null, null, null); 147 cursor.moveToFirst(); 148 149 // Retrieve the phone number from the NUMBER column 150 int column = cursor.getColumnIndex(Phone.NUMBER); 151 String number = cursor.getString(column); 152 153 // Do something with the phone number... 154 } 155 } 156 } 157 </pre> 158 159 <p class="note"><strong>Note:</strong> Before Android 2.3 (API level 9), performing a query 160 on the {@link android.provider.ContactsContract.Contacts Contacts Provider} (like the one shown 161 above) requires that your app declare the {@link 162 android.Manifest.permission#READ_CONTACTS} permission (see <a 163 href="{@docRoot}guide/topics/security/security.html">Security and Permissions</a>). However, 164 beginning with Android 2.3, the Contacts/People app grants your app a temporary 165 permission to read from the Contacts Provider when it returns you a result. The temporary permission 166 applies only to the specific contact requested, so you cannot query a contact other than the one 167 specified by the intent's {@link android.net.Uri}, unless you do declare the {@link 168 android.Manifest.permission#READ_CONTACTS} permission.</p> 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184
