如何在XML的Fragment中的ListView上方放置浮动操作按钮(FAB)? [英] How do you put a floating action button (FAB) above a ListView in a Fragment in xml?

问题描述

这是我的XML，但是它抱怨我有两个根".

This is my XML but it complains that I have "two roots"..

<ListView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:fab="http://schemas.android.com/apk/res-auto"
    android:id="@android:id/list"
    style="@style/ListView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/ic_add_white_48dp"
    android:layout_gravity="bottom|end"
    fab:elevation="6dp"
    fab:pressedTranslationZ="12dp"
    fab:backgroundTint="@color/accent"/>

如果我将它们都包装在另一个根目录(例如RelativeLayout或FrameLayout)中，则我的应用程序将崩溃...

If I wrap them both in another root such as RelativeLayout or FrameLayout my app crashes...

原因:java.lang.ClassCastException:android.widget.FrameLayout 无法转换为android.widget.ListView

Caused by: java.lang.ClassCastException: android.widget.FrameLayout cannot be cast to android.widget.ListView

我的ListView是由片段中的适配器填充的，就像这样...

My ListView is populated by an adapter in my Fragment like so...

ListView mListView = (ListView) inflater.inflate(R.layout.main_list_fragment, container, false);

FloatingActionButton myFab = (FloatingActionButton) mListView.findViewById(R.id.fab);
myFab.setOnClickListener(new View.OnClickListener() {
  public void onClick(View v) {
    //// TODO: 23/09/15
  }
});

int[] to = new int[]{R.id.item};
String[] columns = new String[]{"name"};
listAdapter = new CustomAdapter(this.getActivity(), null, columns, to);
this.setListAdapter(listAdapter);

如何构造XML，以使FAB悬浮在ListView上方?

How do I structure my XML so that I have my FAB floating above the ListView?

推荐答案

您可以按以下方式使用CoordinatorLayout布局. 您在上方列表视图中的含义是什么，如果您在列表顶部，则必须更改android:layout_gravity="top"

You can use CoordinatorLayout layout as follow. What do you meant by above list view, if you meant at top of list then you have to change android:layout_gravity="top"

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="left"
    android:background="@color/white"
    android:divider="@null"
    android:orientation="vertical">
    <ListView
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:fab="http://schemas.android.com/apk/res-auto"
        android:id="@android:id/list"
        style="@style/ListView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

<android.support.design.widget.CoordinatorLayout
    android:id="@+id/rootLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/ic_add_white_48dp"
    android:layout_gravity="bottom|end"
    fab:elevation="6dp"
    fab:pressedTranslationZ="12dp"
    fab:backgroundTint="@color/accent"/>
</android.support.design.widget.CoordinatorLayout>

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