android dialog一闪而过两下偶的钛合眼

我的dialog起来后我还没点按钮呢，自己就不见了，怎么回事。一闪而过，停留1S左右的样子

这是dialog所在的Demo（一个添加按钮的响应事件，点击添加按钮时先将该添加信息和已存数组中的逐个比较，如果有相同的就弹出dialog提示【带有确定和取消按钮】，如果添加成功了挑战到列表页）

 dev_reg_add.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    String name = dev_selected.getSelectedItem().toString();
                    for (int i = 0; i <= dev_grp.dev_num; i++) {
                        if (name.equals(dev_grp.dev_list[i].dev_name)) {
                            Dialog dialog = new AlertDialog.Builder(AddDevActivity.this).setIcon(
                                    android.R.drawable.btn_star).setTitle("添加项已存在").setMessage(
                                    "你需要继续添加设备吗").setPositiveButton("是",
                                    new DialogInterface.OnClickListener() {

                                        @Override
                                        public void onClick(DialogInterface dialog, int which) {                                           Toast.makeText(AddDevActivity.this, "继续添加",
                                                    Toast.LENGTH_LONG).show();
                                        }
                                    }).setNeutralButton("否", new DialogInterface.OnClickListener() {
                              public void onClick(DialogInterface dialog, int which) {
                                    Toast.makeText(AddDevActivity.this, "返回", Toast.LENGTH_LONG)
                                            .show();
                                }
                            }).create();

                            dialog.show();
                            name = null;
                            break;
                        }
                    }

                    dev_grp.dev_list[dev_grp.dev_num].dev_name = name;
                    dev_grp.dev_list[dev_grp.dev_num].dev_ip = "192.168.1.";
                    dev_grp.dev_num++;
                    Intent intent = new Intent(AddDevActivity.this, DevListActivity.class);
                    startActivity(intent);
                }
            });
            }