[英]How to toggle two fragments in one activity?
我在应用程序栏中有两个fragment
类和两个按钮-每个按钮都在执行以下操作之一:
fragment
fragment
类的新实例替换容器 fragment
类的新实例 这是示例代码:
private void openReader() {
FragmentManager fragmentManager = getFragmentManager();
ArticleListFragment fragmentList = (ArticleListFragment) fragmentManager.findFragmentById(R.id.action_list);
ArticleReaderFragment fragmentReader = (ArticleReaderFragment) fragmentManager.findFragmentById(R.id.action_reader);
if (fragmentReader==null || ! fragmentReader.isInLayout()) {
if (fragmentList==null || ! fragmentList.isInLayout()) {
FragmentTransaction ft = fragmentManager.beginTransaction();
ft.add(R.id.container_id, new ArticleReaderFragment());
//ft.addToBackStack(null);
ft.commit();
} else {
FragmentTransaction ft = fragmentManager.beginTransaction();
ft.replace(R.id.container_id, new ArticleReaderFragment());
//ft.addToBackStack(null);
ft.commit();
}
}
else {
// fragment.update(...);
}
}
这是activity
XML:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/welcome_page">
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/container_id">
</FrameLayout>
</LinearLayout>
问题是replace
函数不会destroying
旧的fragment
类-单击按钮时会在彼此之间添加越来越多的片段。
谁能告诉我我做错了吗?
我犯了很多错误:
由于我无法动态设置片段ID,因此我需要使用标签
ft.replace(R.id.container_id, new ArticleListFragment(), "Action_list");
要么
ft.add(R.id.container_id, new ArticleListFragment(), "Action_list");
我只需要使用findFragmentByTag()
因为isInLayout()
总是给我错误。
这是该功能的工作版本:
private void openList() {
FragmentManager fragmentManager = getFragmentManager();
ArticleListFragment fragmentList = (ArticleListFragment) fragmentManager.findFragmentByTag("Action_list");
ArticleReaderFragment fragmentReader = (ArticleReaderFragment) fragmentManager.findFragmentByTag("Action_reader");
if (fragmentList==null) {
if (fragmentReader==null) {
FragmentTransaction ft = fragmentManager.beginTransaction();
ft.add(R.id.container_id, new ArticleListFragment(), "Action_list");
//ft.addToBackStack(null);
ft.commit();
} else {
FragmentTransaction ft = fragmentManager.beginTransaction();
ft.replace(R.id.container_id, new ArticleListFragment(), "Action_list");
//ft.addToBackStack(null);
ft.commit();
}
}
else {
// fragment.update(...);
}
}
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