Question

当声音播放完毕时，我试图将暂停图标更改为播放图标。这里有两个ImageButton，第二个ImageButton可以很好地将暂停图标更改为在声音播放完毕时播放，但是第一个按钮不会更改为在声音播放完毕时播放的图标。

public class MainActivity extends AppCompatActivity {


    ImageButton playBtn, playbutton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        playBtn = (ImageButton) findViewById(R.id.button1);
        playbutton= (ImageButton) findViewById(R.id.button2);

        final MediaPlayer sound = MediaPlayer.create(this,R.raw.evumm);

        playBtn.setBackgroundResource(R.drawable.playicon);
        playBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (sound.isPlaying()) {
                    sound.pause();
                    playBtn.setBackgroundResource(R.drawable.playicon);
                } else {

                    sound.start();
                    playBtn.setBackgroundResource(R.drawable.pauseicon);
                }
            }

        });

        sound.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                playBtn.setBackgroundResource(R.drawable.playicon);
            }
        });


        playbutton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                if (sound.isPlaying()) {
                    sound.pause();
                    playbutton.setBackgroundResource(R.drawable.playicon);
                } else {

                    sound.start();
                    playbutton.setBackgroundResource(R.drawable.pauseicon);
                }

            }
        });

        sound.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                playbutton.setBackgroundResource(R.drawable.playicon);
            }
        });


    }
}

这是XML方面

<?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="develop.kokoson.playorstopapp.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Play or Pause !"
        android:textSize="25dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="46dp"
        android:id="@+id/textView" />

    <ImageButton
        android:id="@+id/button1"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:background="@drawable/playicon"
        android:layout_marginTop="81dp"
        android:layout_below="@+id/textView"
        android:layout_centerHorizontal="true" />

    <ImageButton
        android:id="@+id/button2"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:background="@drawable/playicon"
        android:layout_centerVertical="true"
        android:layout_alignLeft="@+id/button1"
        android:layout_alignStart="@+id/button1" />

   </RelativeLayout>

Answer 1

因为MediaPlayer类的一个实例只有一个OnCompletionListener侦听器，所以调用

sound.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
    @Override
    public void onCompletion(MediaPlayer mp) {
        playBtn.setBackgroundResource(R.drawable.playicon);
    }
});

它将注册一个新的侦听器，该侦听器设置了playBtn按钮的图标。之后，您致电

sound.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
    @Override
    public void onCompletion(MediaPlayer mp) {
        playbutton.setBackgroundResource(R.drawable.playicon);
    }
});

它将设置一个新的侦听器，该侦听器设置playbutton按钮的图标并覆盖第一个侦听器。因此，第一个侦听器中的代码未执行且playBtn的图标也未更改的原因。

您应该使用一个侦听器，然后将要执行的所有代码放入其中。

playBtn = (ImageButton) findViewById(R.id.button1);
playbutton= (ImageButton) findViewById(R.id.button2);

final MediaPlayer sound = MediaPlayer.create(this,R.raw.evumm);

playBtn.setBackgroundResource(R.drawable.playicon);

playBtn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {

        if (sound.isPlaying()) {
            sound.pause();
            playBtn.setBackgroundResource(R.drawable.playicon);
        } else {

            sound.start();
            playBtn.setBackgroundResource(R.drawable.pauseicon);
        }
    }

});

playbutton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {

        if (sound.isPlaying()) {
            sound.pause();
            playbutton.setBackgroundResource(R.drawable.playicon);
        } else {

            sound.start();
            playbutton.setBackgroundResource(R.drawable.pauseicon);
        }

    }
});

sound.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
    @Override
    public void onCompletion(MediaPlayer mp) {
        playBtn.setBackgroundResource(R.drawable.playicon);
        playbutton.setBackgroundResource(R.drawable.playicon);
    }
});

在两个ImageButton中完成播放声音后将暂停图标更改为播放图标

1 个答案: