android----Spinner下拉列表控件

Spinner就是有下拉列表功能的控件

1.在布局文件新建TextView，Spinner

2.初始化它们

3.新建一个数据源list  List<String>  new Arraylist<>();

4.添加数据list.add（）;

5.新建一个适配器数组适配器

  arrayAdapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,list);

6.为适配器做一个下拉列表

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

7.加载适配器

spinner.setAdapter(arrayDapter);

8.下拉列表设置监听事件

spinner.setOnItemSelectedListener(this);

9.  textView.setText("您选择的城市：");
String cityname=list.get(position);

  textView.setText("您选择的城市："+cityname);   

MainActivity

package com.example.wuzuo.xialaliebiao;

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

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
private TextView textView;
private Spinner spinner;
private List<String> list;
private ArrayAdapter<String> arrayAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView= (TextView) findViewById(R.id.text1);
textView.setText("您选择的城市：");
spinner= (Spinner) findViewById(R.id.spinner1);
//设置数据源
list=new ArrayList<>();
list.add("北京");
list.add("驻马店");
list.add("上海");
list.add("广州");
//新建一个适配器
arrayAdapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,list);
//下拉列表
arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
//下拉列表加载适配器
spinner.setAdapter(arrayAdapter);
//spinner设置监听器
spinner.setOnItemSelectedListener(this);
}

@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String cityname=list.get(position);
textView.setText("您选择的城市："+cityname);

}

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

}
}


main-activity
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
>

<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="#a32a2a"
android:textSize="25dp"
android:id="@+id/text1"/>
<Spinner
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/spinner1">

</Spinner>
</LinearLayout>