android - Kotlin fragment 中的API数据

Question

我正在尝试使用Drawer activity，似乎它有3个文件可以将简单文本显示为This is home Fragment:|

无论如何，我已经跟踪了所有这些文件，并找到了fragment_home.xml，HomeFragment.kt和HomeViewModel.kt

Question

How should I call for API data trough fragments?

码
my code
基于android studio documentation，这是我应该用来获取api数据的代码。

val textView = findViewById<TextView>(R.id.TextView)

// Instantiate the RequestQueue.
val queue = Volley.newRequestQueue(this)
val url = "https://example.com/api/listings"

// Request a string response from the provided URL.
val stringRequest = StringRequest(
    Request.Method.GET, url,
    Response.Listener<String> { response ->
        // Display the first 500 characters of the response string.
        textView.text = "Response is: ${response.substring(0, 500)}"
    },
    Response.ErrorListener { textView.text = "That didn't work!" })

// Add the request to the RequestQueue.
queue.add(stringRequest)

PS: I have tried this code above in empty activity it's working

HomeViewModel.kt

class HomeViewModel : ViewModel() {

    private val _text = MutableLiveData<String>().apply {
        value = "This is home Fragment"
    }
    val text: LiveData<String> = _text
}

HomeFragment.kt

class HomeFragment : Fragment() {

    private lateinit var homeViewModel: HomeViewModel

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        homeViewModel =
            ViewModelProviders.of(this).get(HomeViewModel::class.java)
        val root = inflater.inflate(R.layout.fragment_home, container, false)
        val textView: TextView = root.findViewById(R.id.text_home)
        homeViewModel.text.observe(this, Observer {
            textView.text = it
        })
        return root
    }
}

fragment_home.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/text_home"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:textAlignment="center"
        android:textSize="20sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

Please note, before you try to give down-vote: I am aware this question probably is very basic question, but note that it's my first time ever using fragments (basically newbie in android studio), so yes my questions are kind of basic :)

Answer 1

从片段调用API，您可以

class HomeFragment : Fragment() {

  private lateinit var homeViewModel: HomeViewModel

            override fun onCreateView(
                inflater: LayoutInflater,
                container: ViewGroup?,
                savedInstanceState: Bundle?
            ): View? {
                homeViewModel = ViewModelProviders.of(this).get(HomeViewModel::class.java)

                val root = inflater.inflate(R.layout.fragment_home, container, false)

                val textView: TextView = root.findViewById(R.id.text_home)

                //calling the API
                callAPIDemo(textView)

               // homeViewModel.text.observe(this, Observer {
               //     textView.text = it
               // })

                return root
            }

     fun callAPIDemo(textView: TextView) {
        // Instantiate the RequestQueue.
        val queue = Volley.newRequestQueue(activity)
        val url = "https://example.com/api/listings"

        // Request a string response from the provided URL.
        val stringRequest = StringRequest(
                Request.Method.GET, url,
                Response.Listener<String> { response ->
                    // Display the first 500 characters of the response string.
                    textView.text = "Response is: ${response.substring(0, 500)}"
                },
                Response.ErrorListener { textView.text = "That didn't work!" })

        // Add the request to the RequestQueue.
        queue.add(stringRequest)
    }

        }