activity 开始后立即设置操作栏项目可见性很热吗？

Question

当 Activity 重新启动时，一切正常，但我想在 Activity 启动时设置菜单项可见性。

private boolean userIsCompany = false;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Fragment vacancyListFragment = new VacancyListFragment();
    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_frame, 
                                                           vacancyListFragment).commit();


    GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestIdToken(getString(R.string.default_web_client_id))
            .requestEmail()
            .build();
    mGoogleSignInClient = GoogleSignIn.getClient(this, gso);
    final GoogleSignInAccount account = GoogleSignIn.getLastSignedInAccount(this);

如果 Firebase 中的用户有 child , boolean userIsCompany 将变为 true;

    //      Check if current user is CompanyUser.
    //      If it is addVacancy button will become visible.
    assert account != null;
    companiesUidRef = mRef
            .child("Companies")
            .child(Objects.requireNonNull(account.getId()));
    companiesUidRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists()) {
                userIsCompany = true;
            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });
}

这是 OncreateOptionsMenu 方法

@Override
public boolean onCreateOptionsMenu(final Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.action_bar_menu, menu);
    MenuItem addVacancy = menu.findItem(R.id.action_add_vacancy);
    if(!userIsCompany){
        addVacancy.setVisible(false);
    }
    return true;
}

Answer 1

在 onCreateOptionsMenu 完成菜单初始化之前，变量 userIsCompany 似乎不会为真。解决此问题的方法是在将 userIsCompany 设置为 true 后添加对 invalidateOptionsMenu() 的调用。

这将再次调用 onCreateOptionMenu 并更新其可见性。

activity 开始后立即设置操作栏项目可见性很热吗？

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