SwitchCompat not showing thumb image on Android 5.0 lollipop emulator

问题

I read about the new SwitchCompat that has been introduced to implement the Switch widget in Android 5.0. I tried using the same but I am not able to see the drawable thumb image as seen in below image.

My XML code is as follows,

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="5dp">

    <android.support.v7.widget.SwitchCompat
        android:id="@+id/sampleSwitch"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:showText="false"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="20dp"
        android:text="@string/action" />

    <TextView
        android:id="@+id/switchStatus"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/sampleSwitch"
        android:layout_marginTop="22dp"
        android:text="@string/status"
        android:textAppearance="?android:attr/textAppearanceMedium" />

</RelativeLayout>

I am able to see the thumb image in preview design (graphical layout tab in eclipse) for the above layout but when I run my code I dont see the image.

Preview design

This is the exception I get

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.graphics.drawable.Drawable.getPadding(android.graphics.Rect)' on a null object reference

Please can someone help solve the problem?

回答1:

This is a known issue and you should provide the thumb and track:

    android:thumb="@drawable/thumb"
    android:track="@drawable/bg"

or

    SwitchCompat switchCompat = (SwitchCompat)findViewById(R.id.sampleSwitch);
    switchCompat.setThumbResource(R.drawable.apptheme_switch_thumb_holo_light);
    switchCompat.setTrackResource(R.drawable.apptheme_switch_track_holo_light);

you can use this link to customize it.

Layout:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="5dp">

    <android.support.v7.widget.SwitchCompat
        android:id="@+id/sampleSwitch"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="20dp"
        android:textOff="OFF"
        android:textOn="ON"
        android:text="Toggle Me"
        android:clickable="true"
        android:checked="true" />

</RelativeLayout>

And the codes

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); 

        SwitchCompat switchCompat = (SwitchCompat)findViewById(R.id.sampleSwitch);
        switchCompat.setThumbResource(R.drawable.apptheme_switch_thumb_holo_light);
        switchCompat.setTrackResource(R.drawable.apptheme_switch_track_holo_light);    
    }

}

回答2:

It's a bug with corrupt file in drawable-hdpi on AppCompat https://code.google.com/p/android/issues/detail?id=78262

To fix it, juste override it with this 2 files https://github.com/lopespm/quick-fix-switchcompat-resources Add it on your directory drawable-hdpi

XML

<android.support.v7.widget.SwitchCompat
android:id="@+id/dev_switch_show_dev_only"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>

And nothing was necessary on Java

来源：https://stackoverflow.com/questions/27568560/switchcompat-not-showing-thumb-image-on-android-5-0-lollipop-emulator