旧问重提java.lang.NullPointerException

java.lang.NullPointerException

// at com.android.hellomiss.ablier.onClick(ablier.java:669)

// at android.view.View.performClick(View.java:2408)

// at android.view.View.onKeyUp(View.java:4121)

// at android.widget.TextView.onKeyUp(TextView.java:4367)

// at android.view.KeyEvent.dispatch(KeyEvent.java:1061)

// at android.view.View.dispatchKeyEvent(View.java:3740)

// at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)

// at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)

// at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)

// at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)

// at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)

// at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchKeyEvent(PhoneWindow.java:1667)

// at com.android.internal.policy.impl.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1102)

// at android.app.Activity.dispatchKeyEvent(Activity.java:2063)

// at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1643)

// at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2471)

// at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2441)

// at android.view.ViewRoot.handleMessage(ViewRoot.java:1735)

// at android.os.Handler.dispatchMessage(Handler.java:99)

// at android.os.Looper.loop(Looper.java:123)

// at android.app.ActivityThread.main(ActivityThread.java:4628)

// at java.lang.reflect.Method.invokeNative(Native Method)

// at java.lang.reflect.Method.invoke(Method.java:521)

// at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:880)

// at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:638)

// at dalvik.system.NativeStart.main(Native Method)

这个是什么问题？
谁遇到过此类问题，应该怎么着手解决？