相关疑难解决方法(0)

我正在使用Android架构组件.我想要的是当用户在Edittext中键入"0"并单击按钮以将Fragment替换为新的,并且如果键入任何其他内容后发布Toast错误消息.在问题是当我从新的Fragment(BlankFragment)返回并再次单击按钮并再次输入"0"并单击时,onchange()被多次调用,因此片段被多次创建

FragmentExample.class:

     @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        manager = getActivity().getSupportFragmentManager();
        viewmModel = ViewModelProviders.of(getActivity(), viewModelFactory)
                .get(VModel.class);

        View v = inflater.inflate(R.layout.fragment_list, container, false);   
        b = (Button) v.findViewById(R.id.b);
        et = (EditText) v.findViewById(R.id.et);

        viewmModel.observeData().observe(getActivity(), new Observer<String>() {
            @Override
            public void onChanged(@Nullable String s) {

                if(s.equals("0")) {
                    BlankFragment fragment = (BlankFragment) manager.findFragmentByTag(DETAIL_FRAG);
                    if (fragment == null) {
                        fragment = BlankFragment.newInstance();
                    }
                    addFragmentToActivity(manager,
                            fragment,
                            R.id.root_activity_detail,
                            DETAIL_FRAG
                    );
                } else {
                    Toast.makeText(getContext(), "Wrong text", Toast.LENGTH_SHORT).show();
                }
            }
        });

        b.setOnClickListener(new View.OnClickListener() {
            @Override …

嘿，我正在 android 中的 kotlin flow 工作。我注意到我的 kotlin 流程collectLatest调用了两次，有时甚至更多。我尝试过这个答案，但它对我不起作用。我在我的函数中打印了日志，collectLatest它打印了日志。我正在添加代码

MainActivity.kt

class MainActivity : AppCompatActivity(), CustomManager {

    private val viewModel by viewModels<ActivityViewModel>()
    private lateinit var binding: ActivityMainBinding
    private var time = 0

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        setupView()
    }

    private fun setupView() {
        viewModel.fetchData()

        lifecycleScope.launchWhenStarted {
            repeatOnLifecycle(Lifecycle.State.STARTED) {
                viewModel.conversationMutableStateFlow.collectLatest { data ->
                    Log.e("time", "${time++}")
                   ....
                }
            }
        }
    }
}

ActivityViewModel.kt

class ActivityViewModel(app: Application) : AndroidViewModel(app) {

    var conversationMutableStateFlow = MutableStateFlow<List<ConversationDate>>(emptyList()) …