android studio 菜鸟实战项目 之 spnner实现

1.简单实现效果图：

activity_main.xml文件：

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


MainActivity.java文件：

public class MainActivity extends AppCompatActivity  {
    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);
        //实例化
        textView=(TextView)findViewById(R.id.text);
        spinner=(Spinner)findViewById(R.id.spinner);
        textView.setText("您选择的城市北京");
        //设置数据源
        list=new ArrayList<String>();
        list.add("北京");
        list.add("上海");
        list.add("广州");
        list.add("深圳");
        //新建arrayAdapter,android.R.layout.simple_spinner_item是调用android studio中默认的样式
        adapter=new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,list);
        //adapter设置一个下拉列表
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        //spinner加载适配器
        spinner.setAdapter(adapter);
        //实现监听事件
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @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) {

            }
        });
    }
}

2.自定义实现：添加图标

mainActivity.xml文件：

<TextView
    android:textSize="25sp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/text" />
<Spinner
    android:layout_marginTop="10dp"
    android:id="@+id/spinner"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
</Spinner>

新添加的item.xml文件：

<ImageView
    android:id="@+id/imge"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />
<TextView
    android:layout_marginTop="5dp"
    android:layout_marginLeft="30dp"
    android:id="@+id/city"
    android:textSize="25sp"
    android:textColor="#ff0000"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

mainActivity.java文件：

public class MainActivity extends Activity implements AdapterView.OnItemSelectedListener{
    private TextView textView;
    private Spinner spinner;
    private List<Map<String,Object>> dataList;
    private SimpleAdapter adapter;
    private String[] cityName={"上海","广州","北京","深圳","杭州","南京"};
    private int[] icon={R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher,R.mipmap.ic_launcher};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //实例化
        textView=(TextView)findViewById(R.id.text);
        textView.setText("您选择的城市是上海");
        spinner=(Spinner)findViewById(R.id.spinner);
        //准备数据源
        dataList=new ArrayList<>();
        //新建适配器,特别要注意对from和to两个变量的定义
        adapter=new SimpleAdapter(this,getData(),R.layout.item,new String[]{"image","city"},new int[]{R.id.imge,R.id.city});
        //加载适配器
        spinner.setAdapter(adapter);
        //实现监听事件
        spinner.setOnItemSelectedListener(this);
    }
    private List<Map<String,Object>> getData(){
        for(int i=0;i<cityName.length;i++){
            Map<String,Object>map=new HashMap<>();
            map.put("image",icon[i]);
            map.put("city",cityName[i]);
            dataList.add(map);
        }
        return dataList;
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        String city= dataList.get(position).toString();
        textView.setText("您选择的城市是"+city);
        Toast.makeText(this,"您选择的城市是"+city,Toast.LENGTH_SHORT).show();

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

    }
}