Spinner

<resources>
<string name="app_name">HelloWorld</string>

<string-array name="city_labels">
<item>北京</item>
<item>上海</item>
<item>广州</item>
<item>深圳</item>
</string-array>
</resources>

<?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:orientation="vertical"
tools:context="com.pingyijinren.helloworld.MainActivity">

<Spinner
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:entries="@array/city_labels"
android:id="@+id/spinner"></Spinner>
</LinearLayout>

package com.pingyijinren.helloworld;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Spinner;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
private Spinner spinner;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

spinner=(Spinner)findViewById(R.id.spinner);
spinner.setPrompt("选择你所在的城市");
spinner.setOnItemSelectedListener(this);
}

@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String[] cities=getResources().getStringArray(R.array.city_labels);
Toast.makeText(this,cities[position]+"",Toast.LENGTH_SHORT).show();
}

@Override
public void onNothingSelected(AdapterView<?> parent) {
}
}