按钮单击时的 AnimationDrawable 错误

Question

我相信我的 xml 是正确的，但我不确定是什么导致我的代码出现此错误。我正在尝试在 imagebutton 上尝试 animationdrawable，但每次单击按钮时都会出错。

这是我的动画列表“music_icon”：

    <animation-list xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/selected" android:oneshot="true">
        <item android:drawable="@drawable/musicon1" android:duration="50" />
        <item android:drawable="@drawable/musicon2" android:duration="50" />
        <item android:drawable="@drawable/musicon3" android:duration="50" />
        <item android:drawable="@drawable/musicon4" android:duration="50" />
        <item android:drawable="@drawable/musicon5" android:duration="50" />
    </animation-list>

我的 mainActivity.java：

import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageButton;
import android.graphics.drawable.AnimationDrawable;


public class HomeScreen extends AppCompatActivity {

ImageButton musicEnable_ImageButton;
Handler musicIcon_animate = new Handler();
int ArrayPos = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home_screen);

    musicEnable_ImageButton = (ImageButton) findViewById(R.id.soundEnable_button);
    musicEnable_ImageButton.setBackgroundResource(R.drawable.musicoff);
    musicEnable_ImageButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            musicEnable_ImageButton.setBackgroundResource(R.drawable.music_icon);
            final AnimationDrawable frameAnimation = (AnimationDrawable) musicEnable_ImageButton.getBackground();
            frameAnimation.start();
        }
    });
}

我的 layout.xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="wrap_content" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".HomeScreen"
    android:background="@android:drawable/screen_background_dark_transparent"
    android:clickable="true"
    android:id="@+id/homescreen_view">

    <Button
        android:layout_width="100.0dp"
        android:layout_height="25.0dp"
        android:text="Help"
        android:id="@+id/instructionsButton"
        android:layout_alignParentTop="false"
        android:layout_alignParentStart="true"
        android:textColor="#05ffda"
        android:background="@android:color/holo_purple"
        android:longClickable="true" />

    <ImageButton
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:scaleType="centerCrop"
        android:id="@+id/soundEnable_button"
        android:layout_alignParentTop="true"
        android:layout_alignParentEnd="true"
        android:longClickable="true"
        android:nestedScrollingEnabled="true"/>

    <Button
        style="?android:attr/buttonStyleSmall"
        android:layout_width="100dp"
        android:layout_height="25dp"
        android:text="Highscores"
        android:id="@+id/highscores_button"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:background="@android:color/holo_purple"
        android:textColor="#05ffda" />

    <Button
        style="?android:attr/buttonStyleSmall"
        android:layout_width="100dp"
        android:layout_height="30dp"
        android:text="Play Game"
        android:id="@+id/startGame_button"
        android:background="@android:color/holo_purple"
        android:textColor="#05ffda"
        android:layout_marginTop="175dp"
        android:singleLine="true"
        android:layout_alignParentTop="false"
        android:layout_centerHorizontal="true" />

</RelativeLayout>

以下是错误信息：

06-07 05:00:48.004 19844-19844/com.example.comp.app_name E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.ClassCastException: android.graphics.drawable.StateListDrawable cannot be cast to android.graphics.drawable.AnimationDrawable
at com.example.comp.app_name.HomeScreen$1.onClick(HomeScreen.java:36)
at android.view.View.performClick(View.java:4240)
at android.view.View$PerformClick.run(View.java:17721)
at android.os.Handler.handleCallback(Handler.java:730)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)

Answer 1

两件事：

1. 改变你的drawable（去掉selector标签）：

<animation-list xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/selected" android:oneshot="true">
    <item android:drawable="@drawable/musicon1" android:duration="50" />
    <item android:drawable="@drawable/musicon2" android:duration="50" />
    <item android:drawable="@drawable/musicon3" android:duration="50" />
    <item android:drawable="@drawable/musicon4" android:duration="50" />
    <item android:drawable="@drawable/musicon5" android:duration="50" />
</animation-list>

1. 我看不到你设置musicEnable_ImageButton的背景，你只是想get它......我错过了什么，还是你只是忘记设置背景？