android - 如何在 Android Kotlin 中将 MainActivity 代码转换为片段

Question

我正在尝试将主要活动代码转换为导航抽屉模板中的片段。我看过这篇文章，但这是用 Java 编写的。我可以就如何将以下主要内容转换为片段幻灯片获得一些帮助和指导吗？

我的主要：

package com.example.testingapp

import android.graphics.Color
import android.os.Bundle
import com.google.android.material.floatingactionbutton.FloatingActionButton
import com.google.android.material.snackbar.Snackbar
import androidx.appcompat.app.AppCompatActivity
import android.view.Menu
import android.view.MenuItem
import android.view.inputmethod.EditorInfo
import android.webkit.WebView
import android.webkit.WebViewClient
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // Variable and constants declaration
        val btnShow = findViewById<Button>(R.id.btnShow)
        val editText = findViewById<EditText>(R.id.editText)
        val btnExit = findViewById<Button>(R.id.btnExit)
        val webview = findViewById<WebView>(R.id.webview)
        btnExit.setOnClickListener{
            finish()
        }

        // Function that runs when the showButton is clicked.
        // It takes one argument, which is the text entered by the user.
        // Then it loads a web page, using the text as a part of the url.
        btnShow.setOnClickListener{

            // Declare the text from editText
            val text = editText.text

            // Show the text from the user in a small toast window
            Toast.makeText(this, text, Toast.LENGTH_SHORT).show()

            // Make the webView
            webview.webViewClient = WebViewClient()
            webview.setBackgroundColor(Color.parseColor("#ffffff"))

        }
    }
}

主要的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"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/btnUpdate"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffff"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/btnExit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="16dp"
        android:layout_marginBottom="24dp"
        android:backgroundTint="@color/colorPrimary"
        android:textColor="@android:color/white"
        android:text="Exit"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

    <Button
        android:id="@+id/btnShow"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginBottom="24dp"
        android:backgroundTint="@color/colorPrimary"
        android:text="show temp"
        android:textColor="@android:color/white"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent" />

    <WebView
        android:id="@+id/webview"
        android:layout_width="337dp"
        android:layout_height="386dp"
        android:layout_marginStart="32dp"
        android:layout_marginLeft="32dp"
        android:layout_marginEnd="32dp"
        android:layout_marginRight="32dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.581"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.213" />

    <EditText
        android:id="@+id/editText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:ems="10"
        android:hint="Enter sensor name"
        android:inputType="textPersonName"
        app:layout_constraintBottom_toTopOf="@+id/btnShow"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

目标：将上述主要代码转换为导航抽屉模板中的片段

class GalleryFragment : Fragment() {

    private lateinit var galleryViewModel: GalleryViewModel

    override fun onCreateView(
            inflater: LayoutInflater,
            container: ViewGroup?,
            savedInstanceState: Bundle?): View? {
        galleryViewModel =
            ViewModelProvider(this).get(GalleryViewModel::class.java)
        val root = inflater.inflate(R.layout.fragment_gallery, container, false)
        val textView: TextView = root.findViewById(R.id.text_gallery)
        galleryViewModel.text.observe(viewLifecycleOwner, Observer {
            textView.text = it
        })
        return root 
    }
}

\

标签： androidkotlinandroid-fragments

Answer 1

您发布的答案似乎直截了当，但我看到 Java 对新的 Kotlin Android 开发人员来说是多么难以理解。不过，我强烈建议您尝试一下，学习一点 Java 也可以让您更好地理解 Kotlin。

我试图以尽可能少的代码更改来回答，因此将来如何重现它会更加明显。只有大约三行发生了变化。

import android.graphics.Color
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.webkit.WebView
import android.webkit.WebViewClient
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
import androidx.fragment.app.Fragment

class MainFrag: Fragment() {
    override fun onCreateView(inflater: LayoutInflater,
                              container: ViewGroup?, savedInstanceState: Bundle?): View?
    = inflater.inflate(R.layout.activity_main, container, false).apply {

        // Variable and constants declaration
        val btnShow = findViewById<Button>(R.id.btnShow)
        val editText = findViewById<EditText>(R.id.editText)
        val btnExit = findViewById<Button>(R.id.btnExit)
        val webview = findViewById<WebView>(R.id.webview)
        btnExit.setOnClickListener { activity?.finish() }

        // Function that runs when the showButton is clicked.
        // It takes one argument, which is the text entered by the user.
        // Then it loads a web page, using the text as a part of the url.
        btnShow.setOnClickListener {

            // Declare the text from editText
            val text = editText.text

            // Show the text from the user in a small toast window
            Toast.makeText(context, text, Toast.LENGTH_SHORT).show()

            // Make the webView
            webview.webViewClient = WebViewClient()
            webview.setBackgroundColor(Color.parseColor("#ffffff"))
        }
    }
}