Material Design on Nexus 5 with Android L

问题

My app crashes on Android L but it works on android kitkat. Also There is no RippleDrawable on the layout. Here is Exception and layout ;

Xml Layout :

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/page_background">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:inputType="textEmailAddress"
        android:ems="10"
        android:id="@+id/usernameET"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="100dp"
        android:hint="@string/username_hint" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:inputType="textPassword"
        android:ems="10"
        android:id="@+id/passwordET"
        android:layout_below="@+id/usernameET"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp"
        android:hint="@string/password_hint" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="60dp"
        android:layout_marginRight="60dp"
        android:text="@string/login_text"
        android:id="@+id/loginBtn"
        android:background="@drawable/positive_button_selector"
        android:textColor="#fff"
        android:layout_below="@+id/passwordET"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="40dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/register_text"
        android:id="@+id/registerText"
        android:layout_below="@+id/loginBtn"
        android:layout_marginLeft="50dp"
        android:layout_marginTop="40dp"
        android:textColor="@color/accent_color"
        android:textSize="16sp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/forget_password"
        android:id="@+id/forgetText"
        android:layout_below="@+id/registerText"
        android:layout_marginLeft="50dp"
        android:layout_marginTop="20dp"
        android:textColor="@color/accent_color"
        android:textSize="16sp" />
</RelativeLayout>

Drawable xml 'positive_button_selector' :

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:state_pressed="false">
        <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
            <solid android:color="@color/accent_color" />
            <corners android:radius="4dp" />
        </shape>
    </item>
    <item android:state_pressed="true">
        <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
            <solid android:color="@color/teal_light" />
            <corners android:radius="4dp" />
        </shape>
    </item>
</selector>

Exception :

> java.lang.NullPointerException: Attempt to invoke virtual method 'int android.content.res.ColorStateList.getColorForState(int[], int)' on a null object reference
            at android.graphics.drawable.RippleDrawable.activateHotspot(RippleDrawable.java:413)
            at android.graphics.drawable.RippleDrawable.setActive(RippleDrawable.java:229)
            at android.graphics.drawable.RippleDrawable.onStateChange(RippleDrawable.java:207)
            at android.graphics.drawable.Drawable.setState(Drawable.java:566)
            at android.view.View.drawableStateChanged(View.java:15576)
            at android.widget.TextView.drawableStateChanged(TextView.java:3477)
            at android.view.View.refreshDrawableState(View.java:15594)
            at android.view.View.handleFocusGainInternal(View.java:4779)
            at android.view.View.requestFocusNoSearch(View.java:7335)
            at android.view.View.requestFocus(View.java:7314)
            at android.view.ViewGroup.onRequestFocusInDescendants(ViewGroup.java:2492)
            at android.view.ViewGroup.requestFocus(ViewGroup.java:2448)
            at android.view.ViewGroup.onRequestFocusInDescendants(ViewGroup.java:2492)
            at android.view.ViewGroup.requestFocus(ViewGroup.java:2448)
            at android.view.ViewGroup.onRequestFocusInDescendants(ViewGroup.java:2492)
            at android.view.ViewGroup.requestFocus(ViewGroup.java:2448)
            at android.view.ViewGroup.onRequestFocusInDescendants(ViewGroup.java:2492)
            at android.view.ViewGroup.requestFocus(ViewGroup.java:2448)
            at android.view.ViewGroup.onRequestFocusInDescendants(ViewGroup.java:2492)
            at android.view.ViewGroup.requestFocus(ViewGroup.java:2448)
            at android.view.ViewGroup.onRequestFocusInDescendants(ViewGroup.java:2492)
            at android.view.ViewGroup.requestFocus(ViewGroup.java:2448)
            at android.view.ViewGroup.onRequestFocusInDescendants(ViewGroup.java:2492)
            at android.view.ViewGroup.requestFocus(ViewGroup.java:2448)
            at android.view.ViewGroup.onRequestFocusInDescendants(ViewGroup.java:2492)
            at android.view.ViewGroup.requestFocus(ViewGroup.java:2448)
            at android.view.ViewGroup.onRequestFocusInDescendants(ViewGroup.java:2492)
            at android.view.ViewGroup.requestFocus(ViewGroup.java:2451)
            at android.view.View.requestFocus(View.java:7281)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1898)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1044)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5749)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
            at android.view.Choreographer.doCallbacks(Choreographer.java:580)
            at android.view.Choreographer.doFrame(Choreographer.java:550)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
            at android.os.Handler.handleCallback(Handler.java:738)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5070)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:836)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:631)

回答1:

This issue is caused by an old preview version of Lollipop. If you update your device to the latest preview version you will not see this crash anymore.

The comments mention that the crash occurred in version LPV81C which was released in July 2014. The latest preview version as of Oct 27 2014 is LPX13D which does not have this issue.

来源：https://stackoverflow.com/questions/26584131/material-design-on-nexus-5-with-android-l