Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()解决fang'f

写了一个Adapter适配器，调用的时候报错：

java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference
                      at android.widget.AbsSpinner.onMeasure(AbsSpinner.java:206)
                      at android.view.View.measure(View.java:22071)
                      at android.support.constraint.ConstraintLayout.internalMeasureChildren(ConstraintLayout.java:934)
                      at android.support.constraint.ConstraintLayout.onMeasure(ConstraintLayout.java:973)
                      at android.view.View.measure(View.java:22071)
                      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
                      at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                      at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
                      at android.view.View.measure(View.java:22071)
                      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
                      at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:400)
                      at android.view.View.measure(View.java:22071)
                      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
                      at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                      at android.view.View.measure(View.java:22071)
                      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
                      at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1514)
                      at android.widget.LinearLayout.measureVertical(LinearLayout.java:806)
                      at android.widget.LinearLayout.onMeasure(LinearLayout.java:685)
                      at android.view.View.measure(View.java:22071)
                      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
                      at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                      at com.android.internal.policy.DecorView.onMeasure(DecorView.java:724)
                      at android.view.View.measure(View.java:22071)
                      at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2422)
                      at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1504)
                      at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1761)
                      at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1392)
                      at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6752)
                      at android.view.Choreographer$CallbackRecord.run(Choreographer.java:911)
                      at android.view.Choreographer.doCallbacks(Choreographer.java:723)
                      at android.view.Choreographer.doFrame(Choreographer.java:658)
                      at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:897)
                      at android.os.Handler.handleCallback(Handler.java:790)
                      at android.os.Handler.dispatchMessage(Handler.java:99)
                      at android.os.Looper.loop(Looper.java:164)
                      at android.app.ActivityThread.main(ActivityThread.java:6494)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at

出现这种空指针报错一般情况是我们自定义的适配器返回的view 为null造成的

@Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        ImageView image = new ImageView(_content);
        image.setBackgroundResource(_resSets[i]);
        Gallery.LayoutParams layoutparams = new Gallery.LayoutParams(300,300); 
        image.setLayoutParams(layoutparams);
        image.setScaleType(ImageView.ScaleType.FIT_XY); 
-        return null;
+        return image;
    }