我如何将字符串从Activity发送到片段

Question

我一直在开发一个应用程序，用户可以登录到活动中，并且会有一个导航抽屉，其中包含“我的个人资料”，“首页”和“设置”片段。在登录时，我将传递从数据库中检索到的帐户的“名称”和“电子邮件”，以便可以在“我的个人资料”片段中显示它，但无法将在“登录活动”中检索到的名称传递给“我的个人资料”片段。

登录活动中的代码

    Bundle bundle = new Bundle();
    bundle.putString("first", extraName);
    ProfileFragment myProfile = new ProfileFragment();
    myProfile.setArguments(bundle);

ProfileFragment中的代码

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Bundle bundle = this.getArguments();
            String name = bundle.getString("first");
            Log.i("PASSED: ","hello " + name);
            Toast.makeText(getActivity(),"Hello " + name, Toast.LENGTH_SHORT);
        return inflater.inflate(R.layout.fragment_js_profile, container, false);
}

我总是得到Error Null对象参考

Process: com.example.myapplication, PID: 31888

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
    at com.example.myapplication.JobSeeker.ProfileFragment.onCreateView(ProfileFragment.java:27)

    at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2439)
    at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManager.java:1460)
    at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
    at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
    at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:802)
    at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManager.java:2625)
    at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2411)
    at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366)
    at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2273)
    at androidx.fragment.app.FragmentManagerImpl$1.run(FragmentManager.java:733)
    at android.os.Handler.handleCallback(Handler.java:789)
    at android.os.Handler.dispatchMessage(Handler.java:98)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6541)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

谢谢，抱歉英语不好。

Answer 1

提及，您的片段处于同一活动或不同活动中。根据您的问题，您的片段代码位于错误的method或function中，即使您未创建view，也尝试打印或获取字符串。

override onActivityCreated()方法在您的片段中，并将这些代码行放入其中。

Bundle bundle = this.getArguments();
            String name = bundle.getString("first");
            Log.i("PASSED: ","hello " + name);
            Toast.makeText(getActivity(),"Hello " + name, Toast.LENGTH_SHORT);

并且不要打扰您onCreateView()方法内的任何内容，只需将这些代码行上方的内容剪切并粘贴到onActivityCreated()中>]

Answer 2

@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    View view= inflater.inflate(R.layout.fragment_js_profile, container, false);
    Bundle bundle = getArguments();
            String name = bundle.getString("first");
            Log.i("PASSED: ","hello " + name);
            Toast.makeText(getActivity(),"Hello " + name, Toast.LENGTH_SHORT);
        return view;

Answer 3

谢谢您的所有回答，我的错误是在Switch Case代码中