threadid=1: thread exiting with uncaught exception (group=0x417cce00)问题

今天拷贝一个开源项目到本项目中，出现：

threadid=1: thread exiting with uncaught exception (group=0x417cce00)问题，原因是Manfest.xml中activity的Theme与Appliacation的Theme冲突，将activity设置android:theme="@android:style/Theme.Holo.Light"问题得到解决。

出现这样的问题如：

W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x41863e00)
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.xmfcdz.jingjia, PID: 21319
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.xmfcdz.jingjia/com.xmfcdz.jingjia.MarkActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2151)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2279)
at android.app.ActivityThread.access$800(ActivityThread.java:142)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1213)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5241)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:818)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:634)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.xmfcdz.jingjia.MarkActivity.<init>(MarkActivity.java:20)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1208)
at android.app.Instrumentation.newActivity(Instrumentation.java:1062)
at com.qihoo360.mobilesafe.loader.c.newActivity(SourceFile:241)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2142)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2279)
at android.app.ActivityThread.access$800(ActivityThread.java:142)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1213)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5241)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:818)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:634)
at dalvik.system.NativeStart.main(Native Method)

此类问题大多跟mainfest.xml文件配置问题有关，比如主题设置错误、未设置activity等。