Android：打开另一个片段 [英] Android: Opening a Fragment from another

问题描述

我是Android新手，这是我的第二款应用。我正在创建一个标签式活动，其中第一个片段具有创建新任务的表单，第二个片段具有所有已保存任务的列表，第三个片段将显示从第二个列表中选择的任务的注释分段。第三个片段也应该像聊天活动一样，当您输入注释时发布注释并点击发送按钮。当我从单独的活动（ CommentsActivity.java 在下面的链接中的GitHub分支中）实现此聊天活动时，该应用程序运行绝对应有的运行。但是，当我尝试从第三个 Fragment 实现相同的代码时，我遇到以下问题：

I am new to Android and this is my second app. I am creating a tabbed activity where the first fragment has a form to create a new task, the second fragment has the list of all the saved tasks, and the third fragment will show the comments on a task when selected from the list in the second fragment. The third fragment is also supposed to act like a chat activity which posts comments when you type them in and tap the send button. When I implement this chat activity from a separate Activity (CommentsActivity.java in the GitHub branch in the link below), the app runs absolutely as it is supposed to. However, when I try to implement the same code from the third Fragment, I have the following problems:

• 我必须在 CommentsFragment TasksFragment.java 中） c>已启动。

• I have to tap the list item (in TasksFragment.java) twice before the CommentsFragment is launched.

该片段仍为空白，未显示任何详细信息或评论。

The fragment remains blank and shows no details or comments.

标题栏搞砸了。当第一次启动 CommentsFragment 时，它会正确设置标题。然而，当我在片段之间滑动时，它随后变成空白。有时甚至会显示最后一个打开片段的标题，而不是当前打开的片段。

The title bar is messed up. It does set the title correctly when CommentsFragment is launched for the first time. However, it becomes blank subsequently, when I swipe between the fragments . Sometimes it even shows the title of the last open fragment instead of the one currently open.

你可以找到我所有的代码在这里： https://github.com/geekskool/android-teamwork/tree/only_fragments

You can find all my code here: https://github.com/geekskool/android-teamwork/tree/only_fragments

其他细节：我在 TasksFragment 和之间传递数据CommentsFragment 包含与主要活动交互的片段交互方法 - AddTask.java 。这是我所知道的唯一方式。如果有更好的方法，请告诉我。

Other details: I am passing the data between the TasksFragment and the CommentsFragment with fragment interaction methods that interact with the main activity--AddTask.java. This is the only way I know of. If there is a better way, please let me know.

推荐答案

我看到你的分支，发现你使用的是 ViewPager 并尝试使用 FragmentTransaction 更新 ViewPager 内的片段。这不起作用，因为创建 ViewPagerAdapter 时已经创建了片段，并且无法将其附加到 ViewPager 通过 FragmentTransaction 。

I saw your branch and noticed that you are using a ViewPager and trying to use FragmentTransaction to update the fragments inside the ViewPager. This does not work as the fragments will already have been created when the ViewPagerAdapter is created and cannot be attached to the ViewPager through a FragmentTransaction.

以下是我解决它的方法。由于我使用的是ViewPager，因此使用 FragmentTransaction 如下所示：

Here is how I solved it. Since I was using a ViewPager, using FragmentTransaction as below did not work:

错误方式：

FragmentManager fm = getSupportFragmentManager();
android.support.v4.app.FragmentTransaction ft = fm.beginTransaction();
CommentsFragment commentsFragment = CommentsFragment.newInstance(mTaskId, mTaskName);
ft.replace(R.id.container, commentsFragment);
ft.addToBackStack(null);
ft.commit();

使用ViewPager，我必须更新填充它的适配器，然后将其设置为正确的片段。这就是我做的：

With the ViewPager, I had to update the adapter populating it and then set it to the correct fragment. This is what I did:

正确的方式：

在onListItemClick（ ）在TasksFragment中，在onFragmentInteraction上调用此接口方法。然后在主要活动AddTask中，按如下方式实现：

In the onListItemClick() in the TasksFragment, call this interface method onFragmentInteraction. And then in the main activity AddTask, implement it as below:

@Override
public void onFragmentInteraction(String taskId, String taskName, String assigneeRef) { 
    CommentsFragment commentsFragment = CommentsFragment.newInstance(taskId, taskName);
    mSectionsPagerAdapter.fragmentList.remove(2);
    mSectionsPagerAdapter.fragmentList.add(commentsFragment);
    mSectionsPagerAdapter.notifyDataSetChanged();
    mViewPager.setCurrentItem(2);
}

希望这有助于您和其他人在更新内部碎片时遇到问题ViewPager。

Hope this helps you and someone else who faces a problem with updating Fragments inside a ViewPager.

这篇关于Android：打开另一个片段的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！