android - 单击后图标消失

Question

我有一个可折叠的工具栏布局和一个 FAB。我在单击时动态更改 FAB 图标。它运作良好。但是当工具栏折叠并再次展开时。单击 FAB 会使图标消失。当我收起再展开时，图标出现了，而且图标变了!

布局.xml

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="@dimen/app_bar_height"
        android:fitsSystemWindows="true"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.design.widget.CollapsingToolbarLayout
            app:expandedTitleMarginStart="16dp"
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            app:collapsedTitleTextAppearance="@style/AppTheme.ToolbarTitleCollapsed"
            app:expandedTitleTextAppearance="@style/AppTheme.ToolbarTitle"
            app:contentScrim="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">

            <ImageView
                android:id="@+id/cover"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:fitsSystemWindows="true"
                android:scaleType="centerCrop"
                app:layout_collapseMode="parallax" />

            <View
                android:layout_width="match_parent"
                android:layout_height="160dp"
                android:layout_gravity="bottom"
                android:background="@drawable/scrim" />

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

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

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

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

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:clickable="true"
        android:focusable="true"
        android:src="@drawable/ic_favorite_black_24dp"
        app:fabSize="normal"
        android:layout_margin="16dp"
        app:layout_anchor="@+id/appbar"
        app:layout_anchorGravity="bottom|right|end" />

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

用于切换 FAB 图标的 Java 代码

final FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (isSelected) {  
 fab.setImageDrawable(ContextCompat.getDrawable(MyActivity.this,R.drawable.ic_favorite_border_black_24dp));
    fab.setColorFilter(Color.WHITE);
    } else {      fab.setImageDrawable(ContextCompat.getDrawable(MyActivity.this,R.drawable.ic_favorite_black_24dp));
      fab.setColorFilter(Color.WHITE);
    }
    isSelected = !isSelected;
    }
    });

Answer 1

这是 Material 设计库 28.0 中的一个错误，已报告

https://issuetracker.google.com/issues/111316656