SwipeRefreshLayout causes NullPointerException in onCreate

问题

Running my app with SwipeRefreshLayout is causing the app to crash. I have tried to debug the issue, but it seems to occur after the setColorScheme in which it goes into ensureLayout

The logcat:

07-09 16:46:56.093: E/AndroidRuntime(18659): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.heath_bar.twitter/com.heath_bar.twitter.MainActivity}: java.lang.NullPointerException
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2328)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2386)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.app.ActivityThread.access$900(ActivityThread.java:169)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1277)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.os.Handler.dispatchMessage(Handler.java:102)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.os.Looper.loop(Looper.java:136)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.app.ActivityThread.main(ActivityThread.java:5476)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at java.lang.reflect.Method.invokeNative(Native Method)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at java.lang.reflect.Method.invoke(Method.java:515)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at dalvik.system.NativeStart.main(Native Method)
07-09 16:46:56.093: E/AndroidRuntime(18659): Caused by: java.lang.NullPointerException
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.support.v4.widget.SwipeRefreshLayout.ensureTarget(SwipeRefreshLayout.java:293)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.support.v4.widget.SwipeRefreshLayout.setColorScheme(SwipeRefreshLayout.java:268)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at com.heath_bar.twitter.MainActivity.onCreate(MainActivity.java:56)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.app.Activity.performCreate(Activity.java:5451)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
07-09 16:46:56.093: E/AndroidRuntime(18659):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2292)
07-09 16:46:56.093: E/AndroidRuntime(18659):    ... 11 more

Here is my code:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main); 


    SwipeRefreshLayout swipeLayout = (SwipeRefreshLayout) findViewById(R.id.swipe_container);
    swipeLayout.setOnRefreshListener(new OnRefreshListener() {

        @Override
        public void onRefresh() {
            // TODO Auto-generated method stub

        }
    });
    swipeLayout.setColorScheme(Color.RED, Color.BLUE, Color.GREEN,
            Color.YELLOW);

}

My xaml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/swipe_container"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<ScrollView
    android:id="@+id/scrollView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >

    <TableLayout
        android:id="@+id/table"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="5dp" />
</ScrollView>
</android.support.v4.widget.SwipeRefreshLayout>

Any ideas why this might be crashing? I have added the correct jar file as well into my project under Android Private Libraries.

All ideas are greatly appreciated. Thank you in advance.

回答1:

Not a hundred percent sure where the problem was, but I believe I had android.support.v4 version 20.0 not 19.1, but for some odd reason, setColorScheme was not marked as deprecated (as it is in 20.0). Deleting the library and re-adding android.support.v4 library version 20.0. Then changing setColorScheme to set setColorSchemeColors fixed the issue.

I hope this can save someone else some time.

回答2:

The answer is that you should set setColorScheme after your swipeRefreshLayout already add childView. try it!

来源：https://stackoverflow.com/questions/24665504/swiperefreshlayout-causes-nullpointerexception-in-oncreate

标签

android

swiperefreshlayout