无法初始化android中的片段中的按钮

Question

我正在使用片段并尝试初始化其中的按钮。以下是我的代码，我无法找到任何错误。但是，当我在按钮上实现onSetCLickListener时，我仍然得到一个空指针异常。我不知道为什么要添加品牌按钮＆＃39;在代码中仍为null。请帮我。感谢

public class BrandsFragment extends Fragment {

    private Button addBrandButton;
    private EditText addBrandText;

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_brands, container, false);
    addBrandText = (EditText)rootView.findViewById(R.id.addBrandText);
    addBrandButton = (Button)rootView.findViewById(R.id.brandsButton);

    addBrandButton.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v){
            Toast.makeText(getActivity(),addBrandText.getText().toString(),Toast.LENGTH_SHORT).show();

        }
    });
   return rootView;
  }
}

以下是我得到的错误：

    java.lang.RuntimeException: Unable to start activity     ComponentInfo{com.swipeit.swipeit/com.swipeit.swipeit.BrandsActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2693)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2760)
        at android.app.ActivityThread.access$900(ActivityThread.java:177)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1448)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:145)
        at android.app.ActivityThread.main(ActivityThread.java:5944)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1389)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1184)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at com.swipeit.swipeit.BrandsFragment.onCreateView(BrandsFragment.java:67)
        at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:953)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1136)
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1499)
        at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:548)
        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1234)
        at android.app.Activity.performStart(Activity.java:6329)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2656)