Android 浮动按钮更改可绘制图像

Question

I have an floating button in my app. The xml layout of my floating button is the below

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

<android.support.design.widget.AppBarLayout
    android:id="@+id/appbar"
     >

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/collapsing_toolbar"
        >


      <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            />

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


<android.support.v4.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

</android.support.v4.widget.NestedScrollView>


 <android.support.design.widget.FloatingActionButton
    android:id="@+id/chrono_btn"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_margin="@dimen/fab_margin"
    android:clickable="true"
    android:src="@drawable/ic_add_black_48dp"
    app:layout_anchor="@+id/appbar"
    app:layout_anchorGravity="bottom|right|end" />

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

What i want is to change the floating button image src programatically when somethings happens. What i tried so far is

    chrono_button.setBackground(getDrawable(R.drawable.ic_done_black_48dp));

But i always get this error I/FloatingActionButton: Setting a custom background is not supported.

What is wrong in my code or is there any ather approach to change the drawable image of a floating button programatically?

Answer 1

One details that might be good clarifying is the setImageDrawable method is available for the FloatingActionButton class but not for View . So if you are having issues finding this method just cast the fab like:

((FloatingActionButton)mItemPlaying.getRootView().findViewById(R.id.fab)).setImageDrawable(ContextCompat.getDrawable(context, R.drawable.ic_play_arrow_white_24dp));

Answer 2

您不需要更改背景，设置图像。

floatingActionButton.setImageDrawable(getResources().getDrawable(R.drawable.ic_full_sad));

Answer 3

fab.setImageResource(R.drawable.yourimagename);