如果 SD 卡中没有 mp3 文件，则显示 toast

Question

在此类中，从 sd 卡播放 mp3 文件，但如果 mp3 文件不可用 应用程序给予“强制关闭” 如果 SD 卡中没有 mp3（不下载）并返回上一个活动，我想要显示 toast 的 cods。请帮助我

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

getInit();
seekUpdation();
}


public void getInit() {  
seek_bar = (SeekBar) findViewById(R.id.seek_bar);
play_button = (Button) findViewById(R.id.play_button);
pause_button = (Button) findViewById(R.id.pause_button);
text_shown = (TextView) findViewById(R.id.text_shown);
play_button.setOnClickListener(this);
pause_button.setOnClickListener(this);
String filePath = Environment.getExternalStorageDirectory() + "/Android/music.mp3";
mediaPlayer = new MediaPlayer();
try {
    mediaPlayer.setDataSource(filePath);
} catch (IllegalArgumentException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (SecurityException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (IllegalStateException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
mediaPlayer.setOnPreparedListener(new OnPreparedListener() {
    @Override
    public void onPrepared(MediaPlayer mediaPlayer) {

    }
});
mediaPlayer.prepareAsync();
seek_bar.setMax(mediaPlayer.getDuration());
}

Runnable run = new Runnable() {

@Override
public void run() {
    seekUpdation();
}
};

public void seekUpdation() {

seek_bar.setProgress(mediaPlayer.getCurrentPosition());
seekHandler.postDelayed(run, 1000);
seek_bar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {

    @Override
    public void onStopTrackingTouch(SeekBar seek_bar) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onStartTrackingTouch(SeekBar seek_bar) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProgressChanged(SeekBar seek_bar, int progress, boolean fromUser) {
        if(fromUser){ 
            mediaPlayer.seekTo(progress); 
            seek_bar.setProgress(progress);
        }

    }
});
}

@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.play_button:
    text_shown.setText("Playing...");
    mediaPlayer.start();
    break;
case R.id.pause_button:
    mediaPlayer.pause();
    text_shown.setText("Paused...");
}

 }

public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { 
if(fromUser){ 
    mediaPlayer.seekTo(progress); 
    seekBar.setProgress(progress);
}
}

Answer 1

在 IOException 捕获块中放置以下代码：

Toast.makeText(context,'No mp3 file found',Toast.LENGTH_SHORT).show();
this.finish()

finish() 将完成当前活动并返回到上一个活动。