dialog的dismiss方法为什么无效？bt_positive bt_negetive是ss布局下的按钮

final Dialog builder=new Dialog(MainActivity.this);
LayoutInflater factor=LayoutInflater.from(MainActivity.this);
final View view=factor.inflate(R.layout.ss,null);
final EditText alertet=(EditText)view.findViewById(R.id.alertet);
final Button bt_positive=(Button)view.findViewById(R.id.bt_positive);
final Button bt_negetive=(Button)view.findViewById(R.id.bt_negetive);
SpannableString spannableString = new SpannableString( title );
ForegroundColorSpan colorSpan = new ForegroundColorSpan(Color.parseColor("#34eb00"));
spannableString.setSpan(colorSpan, 0, spannableString.length(), Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
alertet.setText(readshareprefeenence("ayddata",m[i],Context.MODE_PRIVATE));
builder.setContentView(view);
builder.show();
bt_negetive.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v)
{
builder.show();
builder.dismiss();
}
});