尝试在 getActivity() 上调用虚拟方法 'java.lang.String android.content.Context.getPackageName()

Question

当我尝试在 Fragment 类上创建意图以移动我的活动页面 HomeScreenActivity 时，

Intent intent = new Intent(getActivity(), HomeScreenActivity.class);
startActivity(intent);
getActivity().finish(); 

我在Fabric 上收到以下错误Fatal Exception: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference。我在操作系统版本为 7 的 Galaxy S7 Edge 上收到此错误。在执行Intent intent = new Intent(getActivity(), HomeScreenActivity.class); 行时（LoginFragment.java 上的行号338）

这是我从Fabric 得到的完整日志，

Fatal Exception: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
       at android.content.ComponentName.<init>(ComponentName.java:128)
       at android.content.Intent.<init>(Intent.java:5359)
       at com.example.android.fragments.LoginFragment.handleValidateEmployeeResponse(LoginFragment.java:338)
       at com.example.android.fragments.LoginFragment.access$100(LoginFragment.java:53)
       at com.example.android.fragments.LoginFragment$3.onResponse(LoginFragment.java:249)
       at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$1.run(ExecutorCallAdapterFactory.java:68)
       at android.os.Handler.handleCallback(Handler.java:751)
       at android.os.Handler.dispatchMessage(Handler.java:95)
       at android.os.Looper.loop(Looper.java:154)
       at android.app.ActivityThread.main(ActivityThread.java:6692)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1468)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1358)

Answer 1

尝试使用attach方法

public Activity mActivity;

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    this.mActivity = activity;
}

并像这样使用

Intent intent = new Intent(mActivity, HomeScreenActivity.class);
startActivity(intent);
mActivity.finish();

Answer 2

我做了这样的事情，

拿Activity参考点赞

MainActivity activity = (MainActivity) getActivity();

然后将对象传递到你想要的地方，比如

Intent intent = new Intent(activity , HomeScreenActivity.class);
activity.finish();