[英]variable adapter might not have been initialized error
我的編譯器沒有它。 :( 現在怎么辦?我必須完全重寫整個應用程序嗎?要查看編譯器拒絕的行,請按 Ctrl+F 搜索 recycler_menu.setAdapter(adapter);
嘗試編譯時,編譯器告訴我,“錯誤:變量 celsiusOutput 可能尚未初始化。” recycler_menu.setAdapter(適配器);
如何愛它
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);
}
};
}
帶上這一行recycler_menu.setAdapter(adapter);
在聲明塊之外,如下所示。
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);
}
用null
初始化recycler_menu
RecyclerView recycler_menu = null;
然后在你的方法 LoadMenu() 中,用空檢查包裝它
if (recycler_menu != null) {
recycler_menu.setAdapter(adapter);
}
問題是編譯器無法檢查recycler_menu
是否已初始化,因為初始化過程在另一種方法onCreate
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