Kotlin应用运行后设备白屏问题求助

问题描述 #

开发Kotlin应用，目标实现点击按钮弹出弹窗功能，但运行后设备始终显示空白白屏，按钮在布局预览中可见但运行时不显示，尝试多种方案未解决。

相关代码 #

MainActivity代码 #

import android.app.AlertDialog
import android.os.Bundle
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import com.example.popup.R
import com.example.popup.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {
private var activityMainBinding: ActivityMainBinding? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.lay_custom_dialog)
        title = "POP UP"
        activityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
        // add the following three lines
        activityMainBinding?.btnShowDefaultDialog?.setOnClickListener {
            showDefaultDialog()
        }
    }
    
    override fun onDestroy() {
        activityMainBinding = null
        super.onDestroy()
    }
    
    private fun showDefaultDialog() {
        val alertDialog = AlertDialog.Builder(this)
    
        alertDialog.apply {
            setIcon(R.drawable.ic_hello)
            setTitle("Hello")
            setMessage("I just wanted to greet you. I hope you are doing great!")
            setPositiveButton("Positive") { _, _ ->
                toast("clicked positive button")
            }
            setNegativeButton("Negative") { _, _ ->
                toast("clicked negative button")
            }
            setNeutralButton("Neutral") { _, _ ->
                toast("clicked neutral button")
            }
        }.create().show()
    }
    private fun toast(text: String) = Toast.makeText(this, text, Toast.LENGTH_SHORT).show()
    
    }

activity_main.xml布局 #

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    
        <Button
            android:id="@+id/btnShowDefaultDialog"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_margin="10dp"
            android:text="@string/show_dialog"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="1.0"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.912" />
    
        <Button
            android:id="@+id/btnShowCustomDialog"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_margin="10dp"
            android:text="@string/show_custom_dialog"
            app:layout_constraintBottom_toTopOf="@id/btnShowDefaultDialog"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.238"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.977" />
    
    </androidx.constraintlayout.widget.ConstraintLayout>

AndroidManifest.xml配置 #

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Popup"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
    </application>

</manifest>

问题原因与解决方法 #

核心问题 #

MainActivity的onCreate方法中，先调用setContentView(R.layout.lay_custom_dialog)加载了空白布局（推测lay_custom_dialog本身无可见元素），后续调用DataBindingUtil.setContentView加载activity_main.xml时，布局已被之前的空白布局覆盖，导致运行时显示白屏。

修改方案 #

删除onCreate中的setContentView(R.layout.lay_custom_dialog)代码行，修改后的onCreate方法如下：

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    title = "POP UP"
    activityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
    activityMainBinding?.btnShowDefaultDialog?.setOnClickListener {
        showDefaultDialog()
    }
}

额外检查 #

• 确认lay_custom_dialog.xml是否为空白布局，若后续无需使用可直接删除，避免混淆。
• 确保strings.xml中已定义show_dialog和show_custom_dialog文本资源，防止按钮文本不显示。

内容的提问来源于stack exchange，提问作者Stephen Adegbite