Android——使用Spinner实现下拉列表

时间：2021-07-13 10:12:04

1.执行步骤：

（1）确定数据源（添加一个下拉列表项的list）

（2）.定义适配器，添加数据源（为下拉列表定义一个数组适配器ArrayAdapter）

（3）为适配器设置下拉时的菜单样式

adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
（4）将适配器添加到下拉列表上 

spinner.setAdapter(adapter);
（5）为下拉列表设置各种事件的响应，这个事件响应菜单被选中 

spinner.setOnItemSelectedListener(this);

2.用数组适配器ArrayAdapter实现下拉列表

activity_main.xml

<?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:id="@+id/textview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20sp"
        android:textColor="#ff0000"/>

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

    </Spinner>
</LinearLayout>

MainActivity.java

import android.app.Activity;
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 Activity implements AdapterView.OnItemSelectedListener {

    private TextView textView;
    private Spinner spinner;
    private List<String> list;
    private ArrayAdapter<String> adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView = (TextView) findViewById(R.id.textview);
        spinner = (Spinner) findViewById(R.id.spinner);
        textView.setText("您选择的城市是北京");
        //1.设置数据源
        list = new ArrayList<>();
        list.add("北京");
        list.add("上海");
        list.add("广州");
        list.add("深圳");

        //2.定义适配器
        adapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,list);

        //3.adapter设置下拉样式
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        //4.spinner加载适配器
        spinner.setAdapter(adapter);

        //5.spinner设置监听器
        spinner.setOnItemSelectedListener(this);
    }

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

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

3.用简单适配器SimpleAdapter实现下拉列表

simple.xml

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

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <ImageView
            android:id="@+id/seclet_image"
            android:layout_width="60dp"
            android:layout_height="60dp" />
        <TextView
            android:id="@+id/select_text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </LinearLayout>

    <Spinner
        android:id="@+id/simple_spinner"
        android:layout_width="wrap_content"
        android:layout_height="60dp">
    </Spinner>

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

    <ImageView
        android:id="@+id/image"
        android:layout_width="40dp"
        android:layout_height="40dp" />

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#ff0000"
        android:textSize="20sp"/>

</LinearLayout>

SimpleActivity.java 

package com.example.sx.spinner;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ImageView;
import android.widget.SimpleAdapter;
import android.widget.Spinner;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Created by sx on 2016/8/17.
 */
public class SimpleActivity extends Activity implements AdapterView.OnItemSelectedListener{

    private ImageView selectImage;
    private TextView selectText;
    private Spinner simpleSpinner;
    private List<Map<String,Object>> dataList;
    private SimpleAdapter adapter;

    private int[] imageList = {R.drawable.beijing,R.drawable.shanghai,R.drawable.guangzhou,R.drawable.shenzhen};
    private String[] textList = {"北京","上海","广州","深圳"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.simple);

        selectImage = (ImageView) findViewById(R.id.seclet_image);
        selectText = (TextView) findViewById(R.id.select_text);
        simpleSpinner = (Spinner) findViewById(R.id.simple_spinner);

        //1.设置数据源
        dataList = new ArrayList<Map<String,Object>>();

        //2.定义适配器
        adapter = new SimpleAdapter(this,getData(),R.layout.item,new String[]{"image","text"},new int[]{R.id.image,R.id.text});

        //3.adapter设置下拉样式，这里样式不要加，因为它并不支持图片和文字一起显示的样式
//        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        //4.spinner加载适配器
        simpleSpinner.setAdapter(adapter);

        //5.spinner设置监听器
        simpleSpinner.setOnItemSelectedListener(this);
    }

    private List<Map<String,Object>> getData() {
        Map<String,Object> map;
        for (int i = 0; i < textList.length; i++) {
            map = new HashMap<>();
            map.put("image",imageList[i]);
            map.put("text",textList[i]);
            dataList.add(map);
        }
        return dataList;
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        selectImage.setImageResource(imageList[position]);
        selectText.setText(textList[position]);
    }

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


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