安卓之返回按钮

要响应安卓的返回按钮，只需添加如下代码

protected void dialog()
{
AlertDialog.Builder builder = new AlertDialog.Builder(this);

builder.setMessage("确定要退出吗？");
builder.setTitle("提示");
builder.setPositiveButton("确定", new android.content.DialogInterface.OnClickListener() {

public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
dialog.dismiss();
North.this.finish();

}
});

builder.setNegativeButton("取消", new android.content.DialogInterface.OnClickListener() {

public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
dialog.dismiss();
}
});


builder.create().show();

}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if(keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0)
{
dialog();
return false;
}

return false;
}

但是在真机调试的时候会提示 没哟 权限 提示 cannot open kaycharmap file ，在网上查了一下，没有找到解决方案

哪位大大知道的话 请告知在下