如何在 android 应用程序中设置最大音量？

Question

package com.example.va_embedding

import android.content.Context
import android.media.AudioManager
import android.media.MediaPlayer
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.provider.MediaStore
import android.util.Log
import android.view.View
import android.widget.MediaController
import android.widget.SeekBar
import android.widget.VideoView
import android.widget.SeekBar.OnSeekBarChangeListener
import kotlinx.android.synthetic.main.activity_main.*


class MainActivity : AppCompatActivity() {

    private lateinit var mediaPlayer: MediaPlayer
    private lateinit var audioManager: AudioManager



    fun play(view: View){
        mediaPlayer.start()

    }

    fun pause(view: View){
        mediaPlayer.pause()
    }


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

        getSystemService(Context.AUDIO_SERVICE)

        val maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
        val volumeControl = findViewById<SeekBar>(R.id.seekBar2)

        volumeControl.max(maxVolume)


        val venom = findViewById<VideoView>(R.id.venomvideo)

        venom.setVideoPath("android.resource://" + packageName + "/" + R.raw.venom)

        val mediaC = MediaController(this)

        mediaC.setAnchorView(venom)

        venom.setMediaController(mediaC)

        val vc = findViewById<SeekBar>(R.id.seekBar2)

        vc.setOnSeekBarChangeListener(object : OnSeekBarChangeListener {
            override fun onProgressChanged(seekBar: SeekBar?, progress: Int, fromUser: Boolean) {
                Log.i("SeekBar Changed",progress.toString())
                audioManager.setStreamVolume(AudioManager.STREAM_MUSIC, progress, 0)

            }

            override fun onStartTrackingTouch(seekBar: SeekBar?) {

            }

            override fun onStopTrackingTouch(seekBar: SeekBar?) {

            }
        })

        venom.start()
    }
}

XML layout

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <VideoView
        android:id="@+id/venomvideo"
        android:layout_width="333dp"
        android:layout_height="568dp"
        android:layout_marginBottom="5dp"
        app:layout_constraintBottom_toTopOf="@+id/seekBar2"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <SeekBar
        android:id="@+id/seekBar2"
        android:layout_width="249dp"
        android:layout_height="73dp"
        android:layout_marginStart="70dp"
        android:layout_marginEnd="70dp"
        android:layout_marginBottom="50dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Issue/Error max unresolved reference

Objective max volume varies from device to device the aim of this code is to set a max volume variable that captures max volume of the device and the user can vary the volume through the seekbar accordingly

SDK version is 28

I am using android studio 3.6.1

Answer 1

You need to initialize your audioManager.

audioManager = getSystemService(Context.AUDIO_SERVICE) as AudioManager