Spinner的简单使用

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实现一个Spinner需要完成以下五个步骤。
1为下拉列表项定义数据源;

<resources>    <string-array name="cityname">        <item>北京</item>        <item>天津</item>        <item>上海</item>        <item>辽宁</item>    </string-array></resources>

2实例化一个适配器;

private Spinner  spinner ;spinner = (Spinner)findViewById(R.id.spinner);

3为Spinner设置下拉列表下拉时的显示样式;

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

4将适配器添加到Spinner上;

spinner.setAdapter(adapter);

5为Spinner添加监听器,设置各种事件的响应操作。
setOnItemSelectedListener

实例:

package com.example.activity_spinner_zyw109;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;public class MainActivity extends AppCompatActivity {    private TextView textView;    private Spinner  spinner ;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        textView = (TextView)findViewById(R.id.xianshiTextView);        spinner = (Spinner)findViewById(R.id.spinner);        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this ,R.array.cityname ,                android.R.layout.simple_spinner_item);        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);        //绑定适配器        spinner.setAdapter(adapter);        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {            @Override            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {                System.out.println("--Position"+position+"");                String  str =parent.getItemAtPosition(position).toString();                        //str = parent.getItemAtPosition(position).toString();                textView.setText(str);            }            @Override            public void onNothingSelected(AdapterView<?> parent) {            }        });    }}//Cursor 绑定数据库//处理用户请求 填充布局//字符串和字符序列的区别
<?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"    >    <TextView        android:id="@+id/xianshiTextView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Hello World!" />    <Spinner        android:id="@+id/spinner"        android:layout_width="match_parent"        android:layout_height="wrap_content">    </Spinner></LinearLayout>
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