使用Android导航组件中的navigationUp传递数据/捆绑 [英] Pass data/bundle using navigateUp in Android Navigation Component

问题描述

我找到了问题，但代码中没有解决方案

当要进行后按/手动后退时，我想获取数据.我正在使用navigateUp()返回.如何将数据传递到上一个片段? navigateUp()没有任何工具可以将数据传递到上一个片段.甚至我都没有找到使用安全Args 的解决方案一个>.它正在转发数据.我想在向后的Frad B中-> Frag A.

I want to have data when backpress/manual back happens. I am using navigateUp() to go back. How can I pass data to previous fragment? navigateUp() does not have any facility to pass data to previous fragment. Even I did not find solution using Safe Args. It's passing data forward. I want to have in backward Frad B -> Frag A.

我的代码返回上一个片段

My code to go back to previous fragment

Navigation.findNavController(view).navigateUp()

我的问题是，我如何获取上一个片段中的数据.我可以使用

My question is, How can i get data in previous fragment. I can navigate to Frag A from Frag B using

推荐答案

根据 developer.android.com ，您可以将common用于要共享数据的片段 ViewModel 使用其活动范围.

According to developer.android.com, you can use common for fragments where you want to share data ViewModel using their activity scope.

以下是步骤:

1. 创建将保留数据的视图模型:

class SharedViewModel : ViewModel() {
    val dataToShare = MutableLiveData<String>()

    fun updateData(data: String) {
        dataToShare.value = data
    }
}

1. 观察Fragment1中的数据更改:

class Fragment1 : Fragment() {

    private lateinit var viewModel: SharedViewModel

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        viewModel = ViewModelProviders.of(activity!!).get(SharedViewModel::class.java)
        viewModel.dataToShare.observe(this, Observer<String> { dataFromFragment2 ->
            // do something with data
        })
    }
}

1. 更新Fragment2中的数据，现在，如果您正确地处理了导航，则应该能够在Fragment1上接收数据更改:

1. Update data in Fragment2 and if you're handling navigation properly, now, you should be able to receive data changes on Fragment1:

class Fragment2 : Fragment() {

    private lateinit var viewModel: SharedViewModel

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        viewModel = ViewModelProviders.of(activity!!).get(SharedViewModel::class.java)

        updateDataButton.setOnClickListener { v ->
            viewModel.updateData("New data for fragment1")
        }
    }
}

我希望答案会有所帮助.

I hope answer helps.

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