java.lang.RuntimeException：无法启动活动ComponentInfo，并且由以下原因引起：java.lang.NullPointerException：尝试调用虚拟方法

Question

github上有一个项目：https://github.com/adonixis/android-lightbox 我下载了该项目并将其启动到Android Studio中，但没有用。 我不是Java程序员，所以我无法理解Android Studio给出的错误与以下内容有关：

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: ru.adonixis.lightbox, PID: 21749
              java.lang.RuntimeException: Unable to start activity ComponentInfo{ru.adonixis.lightbox/ru.adonixis.lightbox.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void java.io.OutputStreamWriter.write(java.lang.String)' on a null object reference
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
                  at android.app.ActivityThread.-wrap12(ActivityThread.java)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:154)
                  at android.app.ActivityThread.main(ActivityThread.java:6119)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
               Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void java.io.OutputStreamWriter.write(java.lang.String)' on a null object reference
                  at ru.adonixis.lightbox.MainActivity.onCreate(MainActivity.java:230)
                  at android.app.Activity.performCreate(Activity.java:6679)
                  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726) 
                  at android.app.ActivityThread.-wrap12(ActivityThread.java) 
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477) 
                  at android.os.Handler.dispatchMessage(Handler.java:102) 
                  at android.os.Looper.loop(Looper.java:154) 
                  at android.app.ActivityThread.main(ActivityThread.java:6119) 
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 

此错误与什么有关，如何消除？