onCreate正在复制视图 [英] onCreate is duplicating views

问题描述

我正在随意地照着阳光走，我遇到了一个问题.

I'm loosely following the sunshine course and I'm running into a problem.

在我的MainActivity onCreate方法中，它最初称为

In my MainActivity onCreate method, it originally called

  protected void onCreate(Bundle savedInstanceState) {
    mStudentId = Utility.getStudentId(this);
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

根据教程，他们说要添加以下几行

According to the tutorial, they say to add the following lines

if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new TimeTableFragment(), TIMETABLEFRAGMENT_TAG)
                .commit();
    }

结果，现在有两个列表视图彼此重叠，彼此重叠，我看到了以下内容:

As a result, there are now two list views overlayed on top of each other as duplicates, and I see the following:

是什么原因造成的?

Activity_main.xml

Activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:popupTheme="@style/AppTheme.PopupOverlay" />

</android.support.design.widget.AppBarLayout>

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/fragment"
    android:name="com.mcgowan.timetable.itsligotimetables.TimeTableFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:layout="@layout/fragment_main" />


<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="@dimen/fab_margin"
    android:src="@android:drawable/ic_dialog_email" />

activity_detail.xml

activity_detail.xml

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:popupTheme="@style/AppTheme.PopupOverlay" />

</android.support.design.widget.AppBarLayout>


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.android.sunshine.app.DetailActivity"
    tools:ignore="MergeRootFrame" />


<include layout="@layout/fragment_detail" />

<!--<android.support.design.widget.FloatingActionButton-->
<!--android:id="@+id/fab"-->
<!--android:layout_width="wrap_content"-->
<!--android:layout_height="wrap_content"-->
<!--android:layout_gravity="bottom|end"-->
<!--android:layout_margin="@dimen/fab_margin"-->
<!--android:src="@android:drawable/ic_dialog_email" />-->

fragment_main.xml

fragment_main.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".TimeTableFragment"
tools:showIn="@layout/activity_main">


<ListView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/listview_timetable" />

推荐答案

您将得到两个TimeTableFragment，因为您在布局中声明了一个，并且在运行时动态地加载了一个.由于您正在学习课程，因此似乎他们开始教您动态Fragment处理和FragmentTransaction的知识，因此您可能希望从布局中删除<fragment>元素.

You're ending up with two TimeTableFragments, as you've one declared in the layout, and you're loading one dynamically at runtime. Since you're following a course, it would seem that they're starting to teach you about dynamic Fragment handling and FragmentTransactions, so you probably want to remove the <fragment> element from the layout.

但是，您的FragmentTransaction将ID为container的ViewGroup指定为Fragment的容器View.当前，您已经在CoordinatorLayout上设置了该ID，这可能并不是您真正想要的.而是用相同的layout_width和layout_height将<fragment>元素替换为<FrameLayout>，然后将android:id="@+id/container"属性移至该位置.

However, your FragmentTransaction is specifying the ViewGroup with ID container as the container View for your Fragment. Currently, you have that ID set on the CoordinatorLayout, which is probably not really what you want. Instead, replace the <fragment> element with a <FrameLayout>, with the same layout_width and layout_height, and move the android:id="@+id/container" attribute to that.

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