java - 为什么我不能类型转换？

Question

我需要更改星星 ratingBar 的颜色，但出现异常，为什么会发生并且完全可以接受？

结果 Activity

private void setDados() {
        TextView text = (TextView) findViewById(R.id.textView3);
        text.setText((text.getText()) + "" + corretas);
        RatingBar ratingBar = (RatingBar) findViewById(R.id.ratingBar);
        ratingBar.setRating((100*corretas)/(corretas+erradas));
        LayerDrawable stars = (LayerDrawable) ratingBar.getProgressDrawable();
        try {
            stars.getDrawable(2).setColorFilter(Color.YELLOW, PorterDuff.Mode.SRC_ATOP);
        }catch(Exception e){
            e.printStackTrace();
        }
    }

日志

04-18 22:02:39.828  31732-31732/com.morais.daniela.doctorquiz E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.morais.daniela.doctorquiz/com.morais.daniela.doctorquiz.Activity.ResultActivity}: java.lang.ClassCastException: android.support.v7.internal.widget.TintDrawableWrapper cannot be cast to android.graphics.drawable.LayerDrawable
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
            at android.app.ActivityThread.access$600(ActivityThread.java:127)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4448)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.ClassCastException: android.support.v7.internal.widget.TintDrawableWrapper cannot be cast to android.graphics.drawable.LayerDrawable
            at com.morais.daniela.doctorquiz.Activity.ResultActivity.setDados(ResultActivity.java:44)
            at com.morais.daniela.doctorquiz.Activity.ResultActivity.onCreate(ResultActivity.java:36)
            at android.app.Activity.performCreate(Activity.java:4465)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
            at android.app.ActivityThread.access$600(ActivityThread.java:127)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4448)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
            at dalvik.system.NativeStart.main(Native Method)

更新:这在 API 5.0 及更高版本中不起作用，我如何处理 Ice Cream 及更高版本？无需创建星图

Answer 1

因为着色绘图是在 Android 5 中引入的，所以 appcompat-v7 库将绘图包装在 TintDrawable 类中。您可以使用反射来绕过它。使用 this gist然后是这个 fragment :

LayerDrawable stars = (LayerDrawable) XpeceDrawableWrapper.getDrawable(ratingBar.getProgressDrawable());

一定要调用 ratingBar.setProgressDrawable(stars) 来替换原来有色的 drawable。

编辑:原样的要点可能与混淆器不兼容(一些保持类规则应该修复它)。