<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
  xmlns:android="http://schemas.android.com/apk/res/android" 
  xmlns:app="http://schemas.android.com/apk/res-auto" 
  android:orientation="vertical" 
  xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" 
  android:layout_height="match_parent" tools:context="com.bwei.czx.czx.MainActivity"> 
 
  <Button 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_gravity="center" 
    android:text="更換城市" 
    android:id="@+id/btn"/> 
  <TextView 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:gravity="center" 
    android:textSize="30sp" 
    android:id="@+id/name"/> 
 
 
</LinearLayout> 

package com.bwei.czx.czx; 
 
import android.content.Intent; 
import android.os.Bundle; 
import android.support.v7.app.AppCompatActivity; 
import android.view.View; 
import android.widget.Button; 
import android.widget.TextView; 
 
import com.example.city_picker.CityListActivity; 
 
public class MainActivity extends AppCompatActivity { 
 
  private TextView tv; 
 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    Button btn = (Button) findViewById(R.id.btn); 
    tv = (TextView) findViewById(R.id.name); 
    btn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
        CityListActivity.startCityActivityForResult(MainActivity.this); 
 
      } 
    }); 
  } 
  @Override 
  protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    super.onActivityResult(requestCode, resultCode, data); 
    if(requestCode == 101&& resultCode ==102){ 
      String city = data.getStringExtra("city"); 
      tv.setText(city); 
    } 
  } 
}