Spinner is simple and practical

public class Spinner
extends AbsSpinner
implements DialogInterface.OnClickListener

<!--code display01-->
<Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/spinner_city1"
        android:entries="@array/city"
        android:dropDownWidth="50sp"
        android:popupBackground="#0ff"
        android:spinnerMode="dropdown"/>

<!--code display02-->
<Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/spinner_city2"
        android:entries="@array/city"
        android:dropDownWidth="10sp"
        android:popupBackground="#0ff"
        android:prompt="@string/prompt_name"
        style="@android:style/Widget.Spinner" />

<resources>
    <string name="app_name">Spinner</string>
    <!--数组资源代码-->
    <array name="city">
        <item >北京</item>
        <item >杭州</item>
        <item >西安</item>
        <item >成都</item>
    </array>
</resources>

<!--code display03-->
 <Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/spinner_color"
        android:dropDownWidth="100sp"
        android:popupBackground="#0ff"
        android:spinnerMode="dialog"/>

/*
 * main.java
 */
package com.manu.spinner;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ArrayAdapter;
import android.widget.Spinner;

public class MainActivity extends AppCompatActivity {
    private Spinner spinner;
    private String[] colors = {"red","green","blue","yellow","pink"};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //根据id获得Spinner组件
        spinner = (Spinner) findViewById(R.id.spinner_color);
        //创建适配器
        //public ArrayAdapter (Context context,int resource,int textViewResourceId,T[] objects)
        //参数（上下文，系统自带的TextView或自定义的用于显示子项的TextView，要显示的数据）
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,colors);
        spinner.setPrompt("请选择喜欢的颜色！");
        spinner.setAdapter(adapter);
    }
}

/*
* code display04
* 为spinner添加事件监听器
*/
    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent,View view,int position,long id) {
                Toast.makeText(MainActivity.this,spinner.getItemAtPosition(position).toString()+" is selected!",Toast.LENGTH_SHORT).show();
            }
        //Spinner默认显示第一项
        @Override
        public void onNothingSelected(AdapterView<?> parent) {
                Toast.makeText(MainActivity.this,"no selected!",Toast.LENGTH_SHORT).show();
            }
    });

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Get to know spinner for the first time and continue to understand and learn in depth in the future~

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