android - 在保存状态（变量值）的同时在片段之间切换 [edittexts 和 textviews]

Question

我使用 Android Studio (kotlin) 做了一个“导航抽屉活动”。

在 fragment_home.xml 上，我添加了 EditText 和 Buttons。在 MainActivity.kt 上，我添加了计算，以便当按下 Button 时，结果会显示在同一 fragment_home 上的 TextView 中。

问题是当我滑动导航抽屉，并从 fragment_home 更改为另一个片段，然后回到相同的 fragment_home 时，按钮和编辑文本根本不起作用。

请帮忙，我是新手，正在寻找解决方案很多天。

基本上输入了一些值，并且有两个按钮可用：计算和重置。逻辑是，如果任何 inputtext 为空，它将显示消息“输入正确的值”，如果点击重置按钮，它会将值重置为预设值，默认值是浮点数... mainactivity.kt 的代码如下：

类 MainActivity ： AppCompatActivity() { 私有 lateinit var appBarConfiguration：AppBarConfiguration 私有 lateinit var 绑定：ActivityMainBinding

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    binding = ActivityMainBinding.inflate(layoutInflater)
    setContentView(binding.root)

       //values from editText are imported to variables
    val inputcatload2 = findViewById(R.id.inputcatload1) as EditText
    val inputcatconv2 = findViewById(R.id.inputcatconv1) as EditText
    val inputcfr2 = findViewById(R.id.inputcfr1) as EditText

         //values from Textviews are imported to variables
    val outputcatflow2 = findViewById(R.id.outputcatflow1) as TextView
    val outputdistillateflow2 = findViewById(R.id.outputdistillateflow1) as TextView
    val outputtotalfeed2 = findViewById(R.id.outputtotalfeed1) as TextView
    val outputh1passessv2 = findViewById(R.id.outputh1passessv1) as TextView

         //display of error message and declaration of two buttons
    val msg1 = findViewById(R.id.message1) as TextView
    val btn1 = findViewById(R.id.button1) as Button
    val btn2 = findViewById(R.id.button2) as Button


      //if any input is empty, message "enter proper input" is displayed else calculation is done
    btn1.setOnClickListener {
        inputcatload2.text.toString()
        if (inputcatload2.length() == 0 || inputcatload2.text.toString() == ".") {
            val msg2="Please input correct Load"
            msg1.setText(msg2)

        } else if (inputcatconv2.length() == 0 || inputcatconv2.text.toString() == "."){
            val msg2="Please input correct Cat. Conversion"
            msg1.setText(msg2)

        } else if (inputcfr2.length() == 0 || inputcfr2.text.toString() == "."){
            val msg2="Please input correct CFR"
            msg1.setText(msg2)

        } else {
            val msg2="*** RESULTS ***"
            msg1.setText(msg2)

            val val1 = inputcatload2.text.toString().toFloat()
            val val2 = inputcatconv2.text.toString().toFloat()
            val val3 = inputcfr2.text.toString().toFloat()

            val result1 = val1 * 148.72 / 100;
            val rounded1 = String.format("%.2f", result1)
            outputcatflow2.setText(rounded1)

            val result2 = val1 * 148.72/100 * val3;
            val rounded2 = String.format("%.1f", result2)
            outputtotalfeed2.setText(rounded2)


            val result3 = (val1 * 148.72/100 * val3) - (val1 * 148.72/100);
            val rounded3 = String.format("%.2f", result3)
            outputdistillateflow2.setText(rounded3)

            val result4 = (val1 * 148.72/100 * val3)/2;
            val rounded4 = String.format("%.1f", result4)
            outputh1passessv2.setText(rounded4)

        }
    }
         //this is reset button which sets all inputs to default float values
    btn2.setOnClickListener{
        inputcatload2.setText("100")
        inputcatconv2.setText("31.2")
        inputcfr2.setText("1.24")
        msg1.setText("")
        outputcatflow2.setText("")
        outputdistillateflow2.setText("")
        outputtotalfeed2.setText("")
        outputh1passessv2.setText("")
    }



  //everything is unchanged here

    setSupportActionBar(binding.appBarMain.toolbar)

    binding.appBarMain.fab.setOnClickListener { view ->
        Snackbar.make(view, "Built by Umair Fareed\nFor personal use only. Not to be distributed.", Snackbar.LENGTH_LONG)
            .setAction("Action", null).show()
    }
    val drawerLayout: DrawerLayout = binding.drawerLayout
    val navView: NavigationView = binding.navView
    val navController = findNavController(R.id.nav_host_fragment_content_main)
    // Passing each menu ID as a set of Ids because each
    // menu should be considered as top level destinations.
    appBarConfiguration = AppBarConfiguration(
        setOf(
            R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow
        ), drawerLayout
    )
    setupActionBarWithNavController(navController, appBarConfiguration)
    navView.setupWithNavController(navController)
}

标签： androidandroid-studiokotlinandroid-fragmentsandroid-activity