android - 基本的 Android 启动器启动画面

Question

我是编写代码的新手，对于我猜测的可能是一个非常简单的问题，我深表歉意。我关注了 Android 的 Build your first app指导。接下来，我尝试按照一些教程 ( this being one of them ) 添加启动器启动画面。当我在模拟器中运行应用程序时，它的加载速度如此之快，以至于我无法判断启动画面是否有效。有没有办法暂时减慢模拟器的速度以检查启动画面？此外，当单击“发送”按钮时应用程序崩溃，这是没有意义的，因为 sendMessage函数存在于 MainActivity 中。

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.myfirstapp, PID: 9242
    java.lang.IllegalStateException: Could not find method sendMessage(View) in a parent or ancestor Context for android:onClick attribute defined on view class androidx.appcompat.widget.AppCompatButton with id 'button'
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:436)
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:393)
        at android.view.View.performClick(View.java:7125)
        at android.view.View.performClickInternal(View.java:7102)
        at android.view.View.access$3500(View.java:801)
        at android.view.View$PerformClick.run(View.java:27336)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

老实说，我不确定出了什么问题，或者应用程序是否太小以至于无法显示启动画面。我也不确定在这里分享我的项目的最佳方式。所以下面是所有的代码。
AndroidManifest.xml

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity android:name=".SplashActivity"
            android:theme="@style/SplashTheme">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".DisplayMessageActivity"
                  android:parentActivityName=".MainActivity">
            <!-- For API 15 -->
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".MainActivity" />
        </activity>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
            </intent-filter>
        </activity>
    </application>
</manifest>

主 Activity .kt

package com.example.myfirstapp

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.EditText

const val EXTRA_MESSAGE = "come.example.myfirstapp.MESSAGE"

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

    //Called when user taps Send button
    fun sendMessage(view: View)
    {
        val editText = findViewById<EditText>(R.id.editTextTextPersonName)
        val message = editText.text.toString()
        val intent = Intent(this, DisplayMessageActivity::class.java).apply {putExtra(EXTRA_MESSAGE, message)}
        startActivity(intent)
    }
}

显示消息 Activity

package com.example.myfirstapp

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.TextView

class DisplayMessageActivity : AppCompatActivity()
{
    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_display_message)

        //Get the Intent that started this activity and extract the string
        val message = intent.getStringExtra(EXTRA_MESSAGE)

        //Capture the layout's TextView and set the string as its text
        val text = findViewById<TextView>(R.id.textView).apply {text = message}
    }
}

飞溅 Activity

package com.example.myfirstapp

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity

class SplashActivity : AppCompatActivity()
{
    override fun onCreate(savedIntanceState: Bundle?)
    {
        setTheme(R.style.AppTheme)
        super.onCreate(savedIntanceState)
        setContentView(R.layout.activity_main)
    }
}

可绘制的 splash_background.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android"
    android:opacity="opaque">
    <item android:drawable="@color/colorPrimary" />
    <item>
        <bitmap android:gravity="center" android:src="@mipmap/ic_launcher" />
    </item>
</layer-list>

值样式.xml

<resources>
    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

    <!-- Splash Screen theme. -->
    <style name="SplashTheme" parent="Theme.AppCompat.NoActionBar">
        <item name="android:windowBackground">@drawable/splash_background</item>
    </style>
</resources>

很抱歉这个新手问题，我希望我发布它没有违反任何规则，但希望得到一些指导。谢谢!
编辑 - 来自 S T 的帮助后更新错误

Answer 1

如果您想为首次发布添加教程，这里有很好的解释如何使用幻灯片创建介绍:
https://www.androidhive.info/2016/05/android-build-intro-slider-app/
如果您只想在每次启动应用程序时出现一个简单的启动画面，请参阅以下内容:
https://android.jlelse.eu/the-complete-android-splash-screen-guide-c7db82bce565