StackOverflow2013

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copied!<p>A great feature about using <em><code>fragments</code></em> in your <em><code>activity</code></em> is the ability to add, remove, replace, and perform other actions with them, in response to user interaction. Each set of changes that you commit to the activity is called a transaction and you can perform one using APIs in <em><code>FragmentTransaction</code></em>.</p> <blockquote> <p>Each transaction is a set of changes that you want to perform at the same time. You can set up all the changes you want to perform for a given transaction using methods such as add(), remove(), and replace(). Then, to apply the transaction to the activity, you must call commit(). For doing that you have to call *<code>FragmentTransaction</code>.</p> </blockquote> <p><strong>General Use</strong></p> <pre><code>/ Create new fragment and transaction Fragment newFragment = new ExampleFragment(); FragmentTransaction transaction = getFragmentManager().beginTransaction(); // Replace whatever is in the fragment_container view with this fragment, // and add the transaction to the back stack transaction.replace(R.id.fragment_container, newFragment); transaction.addToBackStack(null); // Commit the transaction transaction.commit(); </code></pre> <p>In this example, <em><code>newFragment</code></em> replaces whatever fragment (if any) is currently in the layout container identified by the <code>R.id.fragment_container ID</code>. By calling <em><code>addToBackStack</code></em>(), the <em>replace transaction</em> is saved to the back stack so the user can reverse the transaction and bring back the previous fragment by pressing the Back button.</p> <p>If you add multiple changes to the transaction (such as another <code>add</code>() or <code>remove</code>()) and call <code>addToBackStack</code>(), then all changes applied before you call <em>commit</em>() are added to the back stack as a single transaction and the Back button will reverse them all together.</p> <p><strong>The order in which you add changes to a <code>FragmentTransaction</code> doesn't matter, except:</strong> </p> <blockquote> <ol> <li>You must call commit() last</li> <li>If you're adding multiple fragments to the same container, then the order in which you add them determines the order they appear in the view hierarchy</li> </ol> </blockquote> <p><strong>Note:</strong> </p> <p>If you do not call addToBackStack() when you perform a transaction that removes a fragment, then that fragment is destroyed when the transaction is committed and the user cannot navigate back to it. Whereas, if you do call addToBackStack() when removing a fragment, then the fragment is stopped and will be resumed if the user navigates back.</p> <p>Reference </p> <ol> <li><a href="http://developer.android.com/reference/android/app/FragmentTransaction.html" rel="nofollow">http://developer.android.com/reference/android/app/FragmentTransaction.html</a></li> <li><a href="http://developer.android.com/guide/components/fragments.html" rel="nofollow">http://developer.android.com/guide/components/fragments.html</a></li> <li><a href="http://www.vogella.com/articles/AndroidFragments/article.html" rel="nofollow">http://www.vogella.com/articles/AndroidFragments/article.html</a></li> <li><a href="http://www.javacodegeeks.com/2013/06/android-fragment-transaction-fragmentmanager-and-backstack.html" rel="nofollow">http://www.javacodegeeks.com/2013/06/android-fragment-transaction-fragmentmanager-and-backstack.html</a></li> </ol>

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