变量适配器可能未初始化错误

Question

我的编译器没有它。：(现在怎么办？我必须完全重写整个应用程序吗？(？要查看编译器拒绝的行，请按Ctrl+F搜索recycler_menu.setAdapter(adapter(；

当试图编译时，编译器告诉我，"错误：变量celsiusOutput可能没有初始化。"recycler_menu.setAdapter(适配器(
如何使用

private AppBarConfiguration mAppBarConfiguration;
FirebaseDatabase database;
DatabaseReference category;
TextView txtFullName;
RecyclerView recycler_menu;
RecyclerView.LayoutManager layoutManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
Toolbar toolbar = findViewById(R.id.toolbar);
toolbar.setTitle("Menu");
setSupportActionBar(toolbar);
//Init Firebase
database = FirebaseDatabase.getInstance();
category = database.getReference("Category");

FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
//set name for user
View headerView = navigationView.getHeaderView(0);
txtFullName = (TextView)findViewById(R.id.txtFullName);
//error app broken will fix later
/*txtFullName.setText(Common.currentUser.getName());*/
//load menu
recycler_menu = (RecyclerView)findViewById(R.id.recycler_menu);
recycler_menu.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
recycler_menu.setLayoutManager(layoutManager);
LoadMenu();

}
private void LoadMenu() {
final FirebaseRecyclerAdapter<Category, MenuViewHolder> adapter = new FirebaseRecyclerAdapter<Category, MenuViewHolder>(Category.class,R.layout.menu_item,MenuViewHolder.class,category) {
@Override
protected void populateViewHolder(MenuViewHolder viewHolder, Category model, int position) {
viewHolder.txtMenuName.setText(model.getName());
Picasso.get().load(model.getImage())
.into(viewHolder.imageView);
Category clickItem = model;
viewHolder.setItemClickListener(new ItemClickListener() {
@Override
public void onClick(View view, int position, boolean isLongClick) {
Toast.makeText(Home.this, "", Toast.LENGTH_SHORT).show();
}
});
recycler_menu.setAdapter(adapter);
}
};
}

Answer 1

将此行recycler_menu.setAdapter(adapter);置于声明块之外，如下所述。

private void LoadMenu() {
final FirebaseRecyclerAdapter<Category, MenuViewHolder> adapter = new FirebaseRecyclerAdapter<Category, MenuViewHolder>(Category.class,R.layout.menu_item,MenuViewHolder.class,category) {
@Override
protected void populateViewHolder(MenuViewHolder viewHolder, Category model, int position) {
viewHolder.txtMenuName.setText(model.getName());
Picasso.get().load(model.getImage())
.into(viewHolder.imageView);
Category clickItem = model;
viewHolder.setItemClickListener(new ItemClickListener() {
@Override
public void onClick(View view, int position, boolean isLongClick) {
Toast.makeText(Home.this, "", Toast.LENGTH_SHORT).show();
}
});
}
};
recycler_menu.setAdapter(adapter);
}

Answer 2

用null初始化recycler_menu

RecyclerView recycler_menu = null;

然后在方法LoadMenu((中，用空检查包装它

if (recycler_menu != null) {
recycler_menu.setAdapter(adapter);
}

问题是编译器无法检查recycler_menu是否已初始化，因为初始化过程在另一种方法onCreate中