我正在开发我的第一个Android应用程序（具有在其他系统（例如Visual Basic）中进行开发的经验。
发生一个奇怪的错误：当我在java活动类中的onCreate之后使用onStart方法时，活动在启动时立即崩溃。而没有onStart的话一切正常（仅使用onCreate）。同样的事情是当我放置onRestart而不是onStart时。
它发生在我的两个不同的活动中，即Main和Help，这两个活动并不相似。重要为什么我需要使用onStart（onRestart）：
在MainActivity中，我希望在每次出现时，在第一次加载以及从其他活动返回后淡入布局，
HelpActivity使用同一框架（ScrollView）中的帮助页面来扩展其他子视图，但是在设备旋转时，它会返回到“帮助目录”，最初是在onCreate中设置为该框架。您会看到，这不是用户想要的。
将应用代码和Logcat。
我将旧的电子阅读器Pocketbook iq 701与Android 2.0.1（通过USB插入）和第三方仿真器YouVawe一起使用，并且两者均出现错误。
如果有人遇到过同样的问题，请告诉我这是Android错误还是我做错了什么。也许我可能会做得过多，但是根据blablabla博士的常规方法，它会更可取，更方便。
提前感谢！
主要活动：
public class MainActivity extends Activity {
public Animation fadeIn;
public View mainView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mainView=(View)findViewById(R.id.linearLayoutMain);
mainView.setVisibility(View.INVISIBLE); //to fadein later
//fade-in animation to use on activity (re)start
fadeIn = AnimationUtils.loadAnimation(this, R.anim.fadein);
}
@Override
protected void onStart() {
super.onStart();
mainView.setVisibility(View.INVISIBLE);
mainView.startAnimation(fadeIn);
mainView.setVisibility(View.VISIBLE);
}
帮助活动：
public class HelpActivity extends Activity {
public LinearLayout layoutHelpFrame;
public View viewHelpPage;
public LayoutInflater inflater;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_help);
//frame to display help content
layoutHelpFrame = (LinearLayout)findViewById(R.id.frameHelp);
//load initially the Help TOC
inflater = getLayoutInflater();
viewHelpPage=inflater.inflate(R.layout.help_0, null);
//if no onStart or if onRestart used, add view here:
// layoutHelpFrame.addView(viewHelpPage);
}
@Override
protected void onStart() {
super.onStart();
//when restarted on orientation change, help page is restored
layoutHelpFrame.addView(viewHelpPage);
}
//on click topic links
public void showHelpTopic(View topiclnk) {
//clear view
layoutHelpFrame.removeView(viewHelpPage);
//get corresponding topic Id by link textview Id
String lnkname=getResources().getResourceEntryName(topiclnk.getId());
String topicN=lnkname.substring(lnkname.length()-1); //1 last char (digit)
int layoutID = MainActivity.getResId("help_"+topicN, R.layout.class);
//load the Help topic into frame
viewHelpPage=inflater.inflate(layoutID, null);
layoutHelpFrame.addView(viewHelpPage);
layoutHelpFrame.scrollTo(0, 0);
}
LogCat（自崩溃时刻起）：
03-20 06:19:18.136: D/AndroidRuntime(10243): Shutting down VM
03-20 06:19:18.136: W/dalvikvm(10243): threadid=3: thread exiting with uncaught exception (group=0x4001b180)
03-20 06:19:18.136: E/AndroidRuntime(10243): Uncaught handler: thread main exiting due to uncaught exception
03-20 06:19:18.146: E/AndroidRuntime(10243): java.lang.RuntimeException: Unable to start activity ComponentInfo{ru.a_z_b_u_k_a.ourabc/ru.a_z_b_u_k_a.ourabc.HelpActivity}: java.lang.ClassCastException: android.widget.ScrollView
03-20 06:19:18.146: E/AndroidRuntime(10243): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2468)
03-20 06:19:18.146: E/AndroidRuntime(10243): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2484)
03-20 06:19:18.146: E/AndroidRuntime(10243): at android.app.ActivityThread.access$2200(ActivityThread.java:119)
03-20 06:19:18.146: E/AndroidRuntime(10243): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1835)
03-20 06:19:18.146: E/AndroidRuntime(10243): at android.os.Handler.dispatchMessage(Handler.java:99)
03-20 06:19:18.146: E/AndroidRuntime(10243): at android.os.Looper.loop(Looper.java:123)
03-20 06:19:18.146: E/AndroidRuntime(10243): at android.app.ActivityThread.main(ActivityThread.java:4325)
03-20 06:19:18.146: E/AndroidRuntime(10243): at java.lang.reflect.Method.invokeNative(Native Method)
03-20 06:19:18.146: E/AndroidRuntime(10243): at java.lang.reflect.Method.invoke(Method.java:521)
03-20 06:19:18.146: E/AndroidRuntime(10243): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
03-20 06:19:18.146: E/AndroidRuntime(10243): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
03-20 06:19:18.146: E/AndroidRuntime(10243): at dalvik.system.NativeStart.main(Native Method)
03-20 06:19:18.146: E/AndroidRuntime(10243): Caused by: java.lang.ClassCastException: android.widget.ScrollView
03-20 06:19:18.146: E/AndroidRuntime(10243): at ru.a_z_b_u_k_a.ourabc.HelpActivity.onCreate(HelpActivity.java:25)
03-20 06:19:18.146: E/AndroidRuntime(10243): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-20 06:19:18.146: E/AndroidRuntime(10243): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2431)
03-20 06:19:18.146: E/AndroidRuntime(10243): ... 11 more
03-20 06:19:18.156: I/dalvikvm(10243): threadid=7: reacting to signal 3
03-20 06:19:18.156: E/dalvikvm(10243): Unable to open stack trace file '/data/anr/traces.txt': Permission denied
03-20 06:19:57.116: D/AndroidRuntime(10322): Shutting down VM
03-20 06:19:57.116: W/dalvikvm(10322): threadid=3: thread exiting with uncaught exception (group=0x4001b180)
03-20 06:19:57.116: E/AndroidRuntime(10322): Uncaught handler: thread main exiting due to uncaught exception
03-20 06:19:57.126: E/AndroidRuntime(10322): java.lang.RuntimeException: Unable to start activity ComponentInfo{ru.a_z_b_u_k_a.ourabc/ru.a_z_b_u_k_a.ourabc.MainActivity}: java.lang.NullPointerException
03-20 06:19:57.126: E/AndroidRuntime(10322): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2468)
03-20 06:19:57.126: E/AndroidRuntime(10322): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2484)
03-20 06:19:57.126: E/AndroidRuntime(10322): at android.app.ActivityThread.access$2200(ActivityThread.java:119)
03-20 06:19:57.126: E/AndroidRuntime(10322): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1835)
03-20 06:19:57.126: E/AndroidRuntime(10322): at android.os.Handler.dispatchMessage(Handler.java:99)
03-20 06:19:57.126: E/AndroidRuntime(10322): at android.os.Looper.loop(Looper.java:123)
03-20 06:19:57.126: E/AndroidRuntime(10322): at android.app.ActivityThread.main(ActivityThread.java:4325)
03-20 06:19:57.126: E/AndroidRuntime(10322): at java.lang.reflect.Method.invokeNative(Native Method)
03-20 06:19:57.126: E/AndroidRuntime(10322): at java.lang.reflect.Method.invoke(Method.java:521)
03-20 06:19:57.126: E/AndroidRuntime(10322): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
03-20 06:19:57.126: E/AndroidRuntime(10322): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
03-20 06:19:57.126: E/AndroidRuntime(10322): at dalvik.system.NativeStart.main(Native Method)
03-20 06:19:57.126: E/AndroidRuntime(10322): Caused by: java.lang.NullPointerException
03-20 06:19:57.126: E/AndroidRuntime(10322): at ru.a_z_b_u_k_a.ourabc.MainActivity.onCreate(MainActivity.java:44)
03-20 06:19:57.126: E/AndroidRuntime(10322): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-20 06:19:57.126: E/AndroidRuntime(10322): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2431)
03-20 06:19:57.126: E/AndroidRuntime(10322): ... 11 more
03-20 06:19:57.136: I/dalvikvm(10322): threadid=7: reacting to signal 3
03-20 06:19:57.136: E/dalvikvm(10322): Unable to open stack trace file '/data/anr/traces.txt': Permission denied
最佳答案
您的layoutHelpFrame不能同时是滚动视图和linearLayout。您必须混淆ID或类似的东西。
给滚动视图和linearLayout指定一个不同的ID，并正确调用它们，它应该可以工作。
关于java - 当onStart(onRestart)进入onCreate之后时， Activity 崩溃，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/22525074/