// java.lang.StringIndexOutOfBoundsException: length=8; regionStart=-1; regionLength=9
// at java.lang.String.startEndAndLength(String.java:298)
// at java.lang.String.substring(String.java:1087)
// at CN.MyPrivateMessages.Calculator.d(Unknown Source)
// at CN.MyPrivateMessages.Calculator.onClick(Unknown Source)
// at android.view.View.performClick(View.java:5204)
// at android.view.View$PerformClick.run(View.java:21153)
// at android.os.Handler.handleCallback(Handler.java:739)
// at android.os.Handler.dispatchMessage(Handler.java:95)
// at android.os.Looper.loop(Looper.java:148)
// at android.app.ActivityThread.main(ActivityThread.java:5417)
// at java.lang.reflect.Method.invoke(Native Method)
// at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
// at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)