mediaPlayer.stop并没有停止

Question

我想要一个按钮负责播放和暂停音乐。我还想根据其状态更改按钮背景。 当我点击＆＃34;播放＆＃34;音乐开始播放，背景图像变为＆＃34;暂停＆＃34;。 当我点击＆＃34;暂停＆＃34;音乐不会停止播放，但背景图像会再次改变为播放＆＃34;

当我将mediaPlayer.stop（）设置为另一个按钮（不是相同的）时，我检查它是否有效，并且它有效。

public boolean isplaying=false;
public void onClick(View view)
{
    int clickedViewId = view.getId();
    switch(clickedViewId){
        case R.id.time_playButton:
            {
                playpauseButton = (Button) findViewById(R.id.time_playButton);
                mediaPlayer = MediaPlayer.create(this,R.raw.time);

                if(isplaying==false){
                    start();
                    return;
                }
                else {
                    stop();
                    return;
                }

            }
        case R.id.time_ytButton:
            //if I write here
            //mediaPlayer.stop() 
            // it working well but this button is for other thing
            startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("https://www.youtube.com/watch?v=JwYX52BP2Sk")));
    }
}

public void start(){
    playpauseButton.setBackgroundResource(R.drawable.pause);
    mediaPlayer.start();
    isplaying=true;
}
public void stop(){
    playpauseButton.setBackgroundResource(R.drawable.play);
    mediaPlayer.stop();
    Toast.makeText(songs.this, "Checking if mediaPlayer.stop() is calliing on and it is but don't know why isn't work", Toast.LENGTH_SHORT).show();
    isplaying=false;
}