我的应用程序启动时没有任何问题。但是，当我登录并且下一个活动即将启动时，应用程序崩溃，出现以下异常：
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:453)
at android.widget.ArrayAdapter.getView(ArrayAdapter.java:415)
at android.widget.AbsSpinner.onMeasure(AbsSpinner.java:204)
at android.widget.Spinner.onMeasure(Spinner.java:602)
at android.view.View.measure(View.java:23169)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1535)
at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:1187)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:706)
at android.view.View.measure(View.java:23169)
at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:1168)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:706)
at android.view.View.measure(View.java:23169)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1535)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:825)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:704)
at android.view.View.measure(View.java:23169)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
at android.view.View.measure(View.java:23169)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1535)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:825)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:704)
at android.view.View.measure(View.java:23169)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at android.view.View.measure(View.java:23169)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:461)
at android.view.View.measure(View.java:23169)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at com.android.internal.policy.DecorView.onMeasure(DecorView.java:716)
at android.view.View.measure(View.java:23169)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2718)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1572)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1855)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1460)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7183)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:949)
at android.view.Choreographer.doCallbacks(Choreographer.java:761)
at android.view.Choreographer.doFrame(Choreographer.java:696)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:935)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
令我惊讶的是，我的类或外部库都没有出现。如果我保留了整个包，下一个活动就会成功开始。但我也不需要使用混淆。这也很奇怪：如果我保留我的整个包裹，它会很好用。但是，如果我保留这两个子包(package.name.technical&package.name.functional(，它将不起作用。
我保存了很多View的东西，这些东西是我在网上找到的。例如：
-keep class android.widget.AutoCompleteTextView {*;}
-keep class android.widget.Spinner {*;}
-keep class android.widget.ArrayAdapter {*;}
-keep public class * extends android.widget.AdapterView {*;}
-keep public class * extends android.widget.Adapter {*;}
-keep public class * extends android.widget.BaseAdapter {*;}
-keep public class * extends android.view.View {
public <init>(android.content.Context);
public <init>(android.content.Context, android.util.AttributeSet);
public <init>(android.content.Context, android.util.AttributeSet, int);
public void set*(...);
}
我还保留了应该开始的活动。
build.gradle.中未启用"shrinkResources">
有人知道为什么吗？我真的很绝望，不知道该怎么办。
有趣的问题！让我们深入研究一下。
首先，什么是null？好吧，在ArrayAdapter.createViewFromResource中只有一个toString()调用，所以必须是这样。
这是几行之后从getItem(position)返回的项目。
getItem很简单：它只是从传递到构造函数的对象的List中返回一个项。
因此，您的问题是，您的Proguard模糊处理导致您将List中的null项传递到其中一个ArrayAdapters中。也许是通过Gson或其他基于反射的反序列化来膨胀模型的问题？