设置Spinner下拉列表

重要知识点，对下拉列表的选项设置监听事件。

public class MainActivity extends AppCompatActivity {

private Spinner sp;
private Spinner sp2;


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

    sp = findViewById(R.id.sp);
    sp2= findViewById(R.id.sp2);
    initsp();
    initsp2();


}

private void initsp() {
    String[] strArr = new String[]{"北京", "邯郸", "永年"};

    ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_item, strArr);
    //构造下拉列表三个参数的含义：1、上下文（this）2、列表项的layout资源ID3、下拉列表显示内容的文本
    sp.setAdapter(adapter);
}
private void initsp2(){
    List<Map<String,Object>> list=new ArrayList<Map<String, Object>>();
    Map<String,Object> map1=new HashMap<>();
    map1.put("icon",R.mipmap.ic_launcher);
    map1.put("text","哈哈哈");
    list.add(map1);
    Map<String,Object> map2=new HashMap<>();
    map2.put("icon",R.mipmap.ic_launcher);
    map2.put("text","....");
    list.add(map2);
    SimpleAdapter adapter=new SimpleAdapter(this,list,R.layout.checkbox,new String[]{"icon","text"},new int[]{R.id.iv,R.id.tv});
    sp2.setAdapter(adapter);
    sp2.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            Spinner spinner= (Spinner) parent;

            Map<String,Object> item= (Map<String, Object>) spinner.getItemAtPosition(position);
            setTitle((CharSequence) item.get("text"));
        }

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

        }
    });
}

}
新建个xml文件对spinner格式进行定义