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