播放完媒體文件時的Android通知

Question

我有一個帶有所有方法的mediaplayer類。 我只是想獲得何時播放文件的指示，但是遇到了麻煩。 方法如下：

public boolean isPlaying()
{
    final boolean still_playing = true;
    mediaplayer.setOnCompletionListener(new OnCompletionListener() 
    {
        @Override
        public void onCompletion(MediaPlayer mp) 
        {
            still_playing = false;
        }
    });
    return still_playing;
}

我遇到錯誤，例如the final local variable cannot be assigned, since it is defined in an enclosing type或者當我嘗試其他操作時，我得到了variabledeclaratorIdexpected

Answer 1

您的final boolean still_playing = true; 是一個常量變量，表示在運行時無法更改。

在程序的后面：

@Override
public void onCompletion(MediaPlayer mp) 
{
    still_playing = false;
}

您正在嘗試更改其價值。

為了解決這個問題，您應該定義boolean still_playing = true; 作為sow這樣的類的成員變量：

public class classExample {
    // member variables
    private boolean still_playing = true;

    public boolean isPlaying() {

        /* I DELETED THE VARIABLE AND DECLARED IT OUTSIDE THE METHOD */

        mediaplayer.setOnCompletionListener(new OnCompletionListener() {
             @Override
             public void onCompletion(MediaPlayer mp) {

                  /* You could declare it here too without the private
                     keyword like this:
                             boolean still_playing = true; */

                  still_playing = false;
             }
        });
        return still_playing;
    }
}