多线程编程--用接口方法实现选城市旅游

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.wang.myapplication.ZuoyeActivity"
android:orientation="vertical">

<TextView
android:layout_width="match_parent"
android:layout_height="40dp"
android:background="#ccc"
android:textSize="20sp"
android:gravity="center"
android:id="@+id/tv_1" />
<TextView
android:layout_width="match_parent"
android:layout_height="40dp"
android:background="#cba"
android:textSize="20sp"
android:gravity="center"
android:layout_marginTop="5dp"
android:id="@+id/tv_2"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="去哪旅游"
android:id="@+id/bt_1"
android:onClick="bt1_OnClick"/>

</LinearLayout>