Question

我试图在碎片中使用Butterknife时得到java.lang.NullPointerException。我错过了什么？

@Bind(R.id.tv_detail_startTime) TextView tv_detail_startTime;

@Override
public View onCreateView(LayoutInflater inflater,
                         @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    v = inflater.inflate(R.layout.fragment_detail_expanlv,
            container, false);
    ButterKnife.bind(getActivity());

    //THIS IS THE LINE WHERE 
    tv_detail_startTime.setText("Trying Butterknife out in Android");

}

如果我使用锅炉板代码来声明tv_detail_startTime，它就可以了。只需使用Bind就会出错。

完成Stacktrace：

10-29 04:30:28.971 24953-24953/com.mavdev.focusoutfacebook E/AndroidRuntime:   FATAL EXCEPTION: main
Process: com.mavdev.focusoutfacebook, PID: 24953
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at     com.mavdev.focusoutfacebook.fragments.scheduledblocks.Fragment_detail_expanlv.onCreateView(Fragment_detail_expanlv.java:424)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:458)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

Answer 1

绑定片段而不是活动

View v = inflater.inflate(R.layout.xxx, container, false);
ButterKnife.bind(this, v);

Answer 2

ButterKnife可能假设您将活动视图绑定到活动，而不是片段。请尝试使用ButterKnife.bind(this, getActivity())（注意额外的这个）。

在片段中使用Butterknife时的java.lang.NullPointerException

2 个答案: