Android navigatorDrawer头中的SetText

Question

 DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
 TextView text = (TextView) drawer.findViewById(R.id.textViewNames);
 text.setText("HELLO");

 NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
 try {
      View header = LayoutInflater.from(this).inflate(R.layout.nav_header_profiler, null);
      navigationView.addHeaderView(header);
      TextView text = (TextView) header.findViewById(R.id.textViewNames);
      text.setText("HELLO");
 } catch (Exception e) {
      Toast.makeText(getApplicationContext(),e.toString(), Toast.LENGTH_LONG).show();
 }

但什么都不起作用。我总是得到`NullPointerException。出于某种原因，这种方法只是简单地诉诸于控件工作：

 @SuppressWarnings("StatementWithEmptyBody")
 @Override
 public boolean onNavigationItemSelected(MenuItem item) {
      TextView textView = (TextView) findViewById(R.id.textViewNames);
      textView.setText(LoginActivity.FIRST_NAME + "\n" + LoginActivity.LAST_NAME);

      // Handle navigation view item clicks here.
      int id = item.getItemId();

      if (id == R.id.nav_camera) {
           // Handle the camera action
      } else if (id == R.id.nav_gallery) {

      } else if (id == R.id.nav_slideshow) {

      } else if (id == R.id.nav_manage) {

      } else if (id == R.id.Find) {

      } else if (id == R.id.LogOut) {

      }

      DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
      drawer.closeDrawer(GravityCompat.START);
      return true;
 }

编辑：我的日志：

Answer 1

删除此属性app:headerlayout=“@layout/nav_header_main”

<android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:menu="@menu/activity_main_activiy_drawer" />

在MainActivity中动态添加和添加

 NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
        View headerView = navigationView.inflateHeaderView(R.layout.nav_header_main_activiy);
        ImageView user_iv = (ImageView) headerView.findViewById(R.id.user_iv);
        TextView fullName_tv = (TextView) headerView.findViewById(R.id.fullName_tv);
       TextView userEmail_tv = (TextView) headerView.findViewById(R.id.userEmail_tv);

        fullName_tv.setText("Your Full Name");
        userEmail_tv.setText("Your Email id");

这在我的案子里起作用了