Question

06/14 10:51:04: Launching 'app' on Pixel 2 API 27.
$ adb shell am start -n "com.wordsforfun.wordsforplay/com.wordsforfun.words.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Error while executing: am start -n "com.wordsforfun.wordsforplay/com.wordsforfun.words.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.wordsforfun.wordsforplay/com.wordsforfun.words.MainActivity }
Error type 3
Error: Activity class {com.wordsforfun.wordsforplay/com.wordsforfun.words.MainActivity} does not exist.

Error while Launching activity

1）我的android应用在版本9上运行，在版本6上落后，但在android 7,8上崩溃。 2）请任何人都可以帮我这个我是Android Studio新手 3）现在做了很多实验，我已经将我的开始活动更改为其他活动，然后它可以正常工作，我将在此处提供主要活动内容

main activity

package com.wordsforfun.words


import android.content.Intent
import android.media.MediaPlayer
import android.os.Bundle
import android.view.Menu
import android.view.MenuItem
import android.widget.Button
import android.widget.Switch
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    lateinit var mp:MediaPlayer
    lateinit var mp2:MediaPlayer
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        var btn = findViewById<Button>(R.id.start)
        var btn2=findViewById<Button>(R.id.btn2)
        val mySwitch=findViewById<Switch>(R.id.switch1)
        mySwitch.setOnCheckedChangeListener { buttonView, isChecked ->
            if(isChecked) {
                mp = MediaPlayer.create(this@MainActivity, resources.getIdentifier(btn.tag as String, "raw", packageName))
                if(mp.isPlaying)
                {
                    return@setOnCheckedChangeListener
                }
                else {
                    mp = MediaPlayer.create(this@MainActivity, resources.getIdentifier(btn.tag as String, "raw", packageName))
                    mp.start()
                }
            }
            else{
                mp.stop()
            }
        }
        btn.setOnClickListener {
            mp2= MediaPlayer.create(this@MainActivity,resources.getIdentifier(btn2.tag as String,"raw",packageName))
            mp2.start()

            var intent = Intent(this@MainActivity,actual_file::class.java)
            startActivity(intent)
        }

    }


    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        val inflater2=menuInflater
        inflater2.inflate(R.menu.customfile2,menu)
        return true
    }
    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        when (item?.itemId) {
            R.id.instructions -> {
                val intent10= Intent(this@MainActivity,instructions::class.java)
                startActivity(intent10)
                return true
            }
            R.id.moreinfo -> {
                val intent11= Intent(this@MainActivity,more_info::class.java)
                startActivity(intent11)
                return true
            }

        }
        return true
    }

}

this is my xml of main activity




<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.wordsforfun.words.MainActivity">

    <Button
        android:id="@+id/btn2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:tag="click"
        android:text="Button"
        android:visibility="invisible" />

    <ImageView
        android:id="@+id/imageView4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:scaleType="centerCrop"
        app:srcCompat="@drawable/p11" />

    <Switch
        android:id="@+id/switch1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="Music"
        android:textColor="#43034E"
        android:textSize="24sp" />

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="150dp"
        android:layout_marginTop="30dp"
        android:background="@drawable/p11"
        android:src="@drawable/r" />

    <androidx.cardview.widget.CardView
        android:id="@+id/a"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        app:cardCornerRadius="50dp"
        app:cardElevation="50dp"
        app:cardMaxElevation="50dp">

        <Button
            android:id="@+id/start"
            android:layout_width="200sp"
            android:layout_height="60sp"
            android:background="@drawable/y1"
            android:tag="start"
            android:text="Play"
            android:textSize="36sp"
            android:textStyle="italic" />

        <ImageView
            android:id="@+id/imageView6"
            android:layout_width="200sp"
            android:layout_height="60sp"
            app:srcCompat="@drawable/y1" />
    </androidx.cardview.widget.CardView>

</RelativeLayout>

Answer 1

尝试从manifest.xml文件更改活动名称

如果是这样的：

<activity android:name="MainActivity">

在活动名称的开头添加句点：

<activity android:name=".MainActivity">

OR

将包名称添加到活动名称的开头：

<activity android:name="com.wordsforfun.words.MainActivity">

Answer 2

实际上我知道我在第一次活动中使用了2张图片0f 800kb，所以它崩溃了

某些设备上的android应用启动错误

2 个答案: