1 page.title=Responding to a Refresh Request 2 3 trainingnavtop=true 4 @jd:body 5 6 <div id="tb-wrapper"> 7 <div id="tb"> 8 9 <!-- table of contents --> 10 <h2>This lesson teaches you to</h2> 11 <ol> 12 <li><a href="#RespondRefresh">Respond to the Refresh Gesture</a></li> 13 <li><a href="#RespondAction">Respond to the Refresh Action</a> 14 </ol> 15 16 <h2>Sample App</h2> 17 18 <ul> 19 <li><a href="{@docRoot}samples/SwipeRefreshLayoutBasic/index.html"> 20 SwipeRefreshLayoutBasic</a></li> 21 </ul> 22 23 24 </div> 25 </div> 26 27 <p> 28 This lesson shows you how to update your app when the user requests a manual 29 refresh, whether the user triggers the refresh with a swipe gesture or by 30 using the action bar refresh action. 31 </p> 32 33 <h2 id="RespondRefresh">Respond to the Refresh Gesture</h2> 34 35 <p> 36 When the user makes a swipe gesture, the system displays the progress 37 indicator and calls your app's callback method. Your callback method is 38 responsible for actually updating the app's data. 39 </p> 40 41 <p> 42 To respond to the refresh gesture in your app, implement the {@link 43 android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener} interface and 44 its {@link 45 android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener#onRefresh 46 onRefresh()} method. The {@link 47 android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener#onRefresh 48 onRefresh()} method is invoked when the user performs a swipe gesture. 49 </p> 50 51 <p> 52 You should put the code for the actual update 53 operation in a separate method, and call that update method from your {@link 54 android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener#onRefresh 55 onRefresh()} implementation. That way, you can use the same update method to 56 perform the update when the user triggers a refresh from the action bar. 57 </p> 58 59 <p> 60 Your update method calls {@link 61 android.support.v4.widget.SwipeRefreshLayout#setRefreshing 62 setRefreshing(false)} when it has finished updating the data. Calling this 63 method instructs the {@link android.support.v4.widget.SwipeRefreshLayout} to 64 remove the progress indicator and update the view contents. 65 </p> 66 67 <p> 68 For example, the following code implements {@link 69 android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener#onRefresh 70 onRefresh()} and invokes the method {@code myUpdateOperation()} to update the 71 data displayed by the {@link android.widget.ListView}: 72 </p> 73 74 <pre>/* 75 * Sets up a SwipeRefreshLayout.OnRefreshListener that is invoked when the user 76 * performs a swipe-to-refresh gesture. 77 */ 78 mySwipeRefreshLayout.setOnRefreshListener( 79 new SwipeRefreshLayout.OnRefreshListener() { 80 @Override 81 public void onRefresh() { 82 Log.i(LOG_TAG, "onRefresh called from SwipeRefreshLayout"); 83 84 // This method performs the actual data-refresh operation. 85 // The method calls setRefreshing(false) when it's finished. 86 myUpdateOperation(); 87 } 88 } 89 );</pre> 90 91 <h2 id="RespondAction">Respond to the Refresh Action</h2> 92 93 <p> 94 If the user requests a refresh by using the action bar, the system calls the 95 {@link android.support.v4.app.Fragment#onOptionsItemSelected 96 onOptionsItemSelected()} method. Your app should respond to this call by 97 displaying the progress indicator and refreshing the app's data. 98 </p> 99 100 <p> 101 To respond to the refresh action, override {@link 102 android.support.v4.app.Fragment#onOptionsItemSelected 103 onOptionsItemSelected()}. In your override method, trigger the {@link 104 android.support.v4.widget.SwipeRefreshLayout} progress indicator by calling 105 {@link android.support.v4.widget.SwipeRefreshLayout#setRefreshing 106 setRefreshing()} with the value {@code true}, then perform the update 107 operation. Once again, you should be doing the actual update in a separate 108 method, so the same method can be called whether the user triggers the update 109 with a swipe or by using the action bar. When the update has finished, call 110 {@link android.support.v4.widget.SwipeRefreshLayout#setRefreshing 111 setRefreshing(false)} to remove the refresh progress indicator. 112 </p> 113 114 <p>The following code shows how to respond to the request action: 115 </p> 116 117 <pre>/* 118 * Listen for option item selections so that we receive a notification 119 * when the user requests a refresh by selecting the refresh action bar item. 120 */ 121 @Override 122 public boolean onOptionsItemSelected(MenuItem item) { 123 switch (item.getItemId()) { 124 125 // Check if user triggered a refresh: 126 case R.id.menu_refresh: 127 Log.i(LOG_TAG, "Refresh menu item selected"); 128 129 // Signal SwipeRefreshLayout to start the progress indicator 130 mySwipeRefreshLayout.setRefreshing(true); 131 132 // Start the refresh background task. 133 // This method calls setRefreshing(false) when it's finished. 134 myUpdateOperation(); 135 136 return true; 137 } 138 139 // User didn't trigger a refresh, let the superclass handle this action 140 return super.onOptionsItemSelected(item); 141 142 }</pre> 143 144 <p class="note"> 145 <strong>Note:</strong> When the user triggers a refresh with a swipe action as 146 described in <a href="#RespondRefresh">Respond to the Refresh Gesture</a>, 147 you do not need to call {@link 148 android.support.v4.widget.SwipeRefreshLayout#setRefreshing setRefreshing()}. 149 The {@link 150 android.support.v4.widget.SwipeRefreshLayout} widget takes care of displaying 151 the progress indicator and removing it when the update has finished. However, 152 if the update is triggered by any means <em>other than</em> a swipe gesture, 153 you need to explicitly turn the progress indicator on with {@link 154 android.support.v4.widget.SwipeRefreshLayout#setRefreshing setRefreshing()}. 155 The method which actually refreshes the data calls {@link 156 android.support.v4.widget.SwipeRefreshLayout#setRefreshing 157 setRefreshing(false)} to signal that the update is finished. 158 </p> 159
