Spinner控件:Spinner绑定的监听是SetOnItemSelectedListener

（一）

1.效果图：ArrayAdapter可以不用设置

arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_item);

2.activity_main.xml

 <?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.example.app3.MainActivity">
 
     <Spinner
         android:id="@+id/spin"
         android:background="@color/colorAccent"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:dropDownVerticalOffset="100dp"
         android:dropDownHorizontalOffset="100dp"
         />
 </LinearLayout>

3.MianActivity.java

 package com.example.app3;
 
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.view.View;
 import android.widget.Adapter;
 import android.widget.AdapterView;
 import android.widget.ArrayAdapter;
 import android.widget.Spinner;
 import android.widget.Toast;
 
 import java.util.ArrayList;
 import java.util.List;
 
 public class MainActivity extends AppCompatActivity {
     private Spinner spinner;
     private List<String> list;
     private ArrayAdapter arrayAdapter;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
 
         spinner=(Spinner)findViewById(R.id.spin);
 
         //新建适配器
         list = new ArrayList<>();
         for (int i=0;i<3;i++){
             list.add("spinner"+i);
         }
         arrayAdapter = new ArrayAdapter(MainActivity.this,android.R.layout.simple_spinner_item,list);
 
         spinner.setAdapter(arrayAdapter);
 
         spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                 Toast.makeText(MainActivity.this,list.get(position),Toast.LENGTH_SHORT).show();
             }
 
             @Override
             public void onNothingSelected(AdapterView<?> parent) {
 
             }
         });
     }
 }

（二）用简单适配器的时候必须设置