<?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">
 
    <Spinner
        android:layout_width="200dp"
        android:id="@+id/spinner"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:spinnerMode="dropdown"
        android:dropDownVerticalOffset="45dp"
        android:background="@null"/>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="45dp"
    android:background="@android:color/holo_blue_dark"
    android:textSize="14sp"
    android:textColor="@android:color/holo_red_light"
    android:gravity="center"/>

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="45dp"
    android:textColor="@android:color/black"
    android:textSize="14sp"
    android:gravity="center"/>

public class MainActivity extends AppCompatActivity{
 
    private String[] starArray = {"水星","金星","地球","火星","木星","土星"};
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initSpinner();
    }
 
    private void initSpinner(){
        //聲明一個(gè)下拉列表的數(shù)組適配器
        ArrayAdapter<String> starAdapter = new ArrayAdapter<String>(this,R.layout.item_select,starArray);
        //設(shè)置數(shù)組適配器的布局樣式
        starAdapter.setDropDownViewResource(R.layout.item_dropdown);
        //從布局文件中獲取名叫sp_dialog的下拉框
        Spinner sp = findViewById(R.id.spinner);
        //設(shè)置下拉框的標(biāo)題，不設(shè)置就沒(méi)有難看的標(biāo)題了
        sp.setPrompt("請(qǐng)選擇行星");
        //設(shè)置下拉框的數(shù)組適配器
        sp.setAdapter(starAdapter);
        //設(shè)置下拉框默認(rèn)的顯示第一項(xiàng)
        sp.setSelection(0);
        //給下拉框設(shè)置選擇監(jiān)聽(tīng)器，一旦用戶(hù)選中某一項(xiàng)，就觸發(fā)監(jiān)聽(tīng)器的onItemSelected方法
        sp.setOnItemSelectedListener(new MySelectedListener());
    }
 
    class MySelectedListener implements AdapterView.OnItemSelectedListener{
 
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
            Toast.makeText(MainActivity.this,"您選擇的是："+starArray[i],Toast.LENGTH_SHORT).show();
        }
 
        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {
 
        }
    }
}

<style name="XSpinnerStyle" parent="android:Widget.ListView.DropDown">
        <!-- 分隔線(xiàn)顏色 -->
        <item name="android:divider">#000000</item>
        <item name="android:dividerHeight">1dp</item>
</style>

 <item name="android:dropDownListViewStyle">@style/XSpinnerStyle</item>