android 关于Tabhost子Activity不能响应退出键的解决办法

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
dialog();
return false;
}
return false;
}
protected void dialog() {
AlertDialog.Builder builder = new AlertDialog.Builder(main.this);
builder.setMessage("确定要退出吗?");
builder.setTitle("提示");
builder.setPositiveButton("确认",
new android.content.DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
dialog.dismiss();
main.this.finish();
}
});
builder.setNegativeButton("取消",
new android.content.DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
builder.create().show();
}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
return false;
}