FirebaseAuth -如何等待值

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.FirebaseApp;

// 初始化FirebaseApp
FirebaseApp.initializeApp();

FirebaseAuth auth = FirebaseAuth.getInstance();
FirebaseUser user = auth.getCurrentUser();

auth.addAuthStateListener(new FirebaseAuth.AuthStateListener() {
    @Override
    public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
        FirebaseUser user = firebaseAuth.getCurrentUser();
        if (user != null) {
            // 用户已登录，可以获取用户信息
            // TODO: 处理用户已登录的逻辑
        } else {
            // 用户未登录或者已注销
            // TODO: 处理用户未登录的逻辑
        }
    }
});