Android Can'；t关闭活动

完成（）；第二次按下“后退”按钮时不工作，仅在当前按下按钮一次时可见和不可见

 @Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK){
        final ImageView im = (ImageView)findViewById(R.id.imageView);
        final ScrollView scrol = (ScrollView)findViewById(R.id.scrollView);
        final LinearLayout layOut = (LinearLayout)findViewById(R.id.layout);
        final TextView text = (TextView)findViewById(R.id.textView);
        final VideoView videoview = (VideoView) findViewById(R.id.video_View);
        videoview.setVisibility(View.INVISIBLE);
        im.setVisibility(View.VISIBLE);
        scrol.setVisibility(View.VISIBLE);
        layOut.setVisibility(View.VISIBLE);
        text.setVisibility(View.VISIBLE);
        return false;
    } else {
        finish();
    }
    return super.onKeyDown(keyCode,event);


}

无法生成apk

@Override
public void onBackPressed(){
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == android.view.KeyEvent.KEYCODE_BACK){
            final ImageView im = (ImageView)findViewById(R.id.imageView);
            final ScrollView scrol = (ScrollView)findViewById(R.id.scrollView);
            final LinearLayout layOut = (LinearLayout)findViewById(R.id.layout);
            final TextView text = (TextView)findViewById(R.id.textView);
            final VideoView videoview = (VideoView) findViewById(R.id.video_View);
            videoview.setVisibility(View.INVISIBLE);
            im.setVisibility(View.VISIBLE);
            scrol.setVisibility(View.VISIBLE);
            layOut.setVisibility(View.VISIBLE);
            text.setVisibility(View.VISIBLE);
            return false;
        } else {
            finish();
        }
        return super.onKeyDown(keyCode, event);


    }
}

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尝试重写onBackPressed（）并将此代码放在那里不会出错…您遇到了什么错误？您试图用上述代码实现什么？嘿………如果您遇到错误或应用程序崩溃，请在此处发布pogcat.“无法构建apk”不是错误。请提供更多信息。完成（）；当按下后退按钮两次时，我发现代码：D