Android_(控件)动态添加或删除Spinner下拉菜单

使用ArrayList动态数组的依赖性实现动态增减Spinner下拉菜单选项功能。

设置一个EditText输入框，当用户输入了文字并单击【添加】按钮的同时，就会将输入的值添加Spinner至下拉菜单的最后一项，接着Spinner会停留在刚刚添加的选项上，单击【删除】按钮则会删除选择的Spinner选项。

运行截图：

程序结构

package com.example.asus.gary_0400;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private static final String[] countriesStr = {"周一","周二","周三","周四","周五"};
    private TextView myTextView;
    private EditText myEditText;
    private Button myButton_add;
    private Button myButton_remove;
    private Spinner mySpinner;
    private ArrayAdapter<String>adapter;
    private List<String> allCountries;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        allCountries = new ArrayList<String>();

        for(int i=0;i<countriesStr.length;i++)
        {
            allCountries.add(countriesStr[i]);
        }

        //新建ArrayAdapter对象并将allCountries传入
        adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_dropdown_item,allCountries);

        adapter.setDropDownViewResource(
                android.R.layout.simple_spinner_dropdown_item);

        //以findViewById()取的对象
        myTextView = (TextView)findViewById(R.id.myTextView);
        myEditText = (EditText)findViewById(R.id.myEditText);
        myButton_add=(Button)findViewById(R.id.myButton_add);
        myButton_remove = (Button)findViewById(R.id.myButton_remove);
        mySpinner = (Spinner)findViewById(R.id.myspinner);

        //将ArrayAdapter添加到Spinner对象中
        mySpinner.setAdapter(adapter);

        myButton_add.setOnClickListener(new Button.OnClickListener() {

            @Override
            public void onClick(View v) {
                String newCountry = myEditText.getText().toString();
                //先比较添加的值是否存在，不存在才可以添加
                for(int i=0;i<adapter.getCount();i++)
                {
                    if(newCountry.equals(adapter.getItem(i))){
                        return;
                    }
                }

                if(!newCountry.equals(""))
                {
                    //将值添加至adapter
                    adapter.add(newCountry);
                    //取得添加的值的位置
                    int position = adapter.getPosition(newCountry);
                    //将Spinner选择在添加的值的位置
                    mySpinner.setSelection(position);
                    //将myEditText清空
                    myEditText.setText("");
                }
            }
        });

        //为myButton_remove添加OnclickListener
        myButton_remove.setOnClickListener(new Button.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(mySpinner.getSelectedItem()!=null)
                {
                    //删除mySpinner的值
                    adapter.remove(mySpinner.getSelectedItem().toString());
                    //将myEditText清空
                    myEditText.setText("");
                    if(adapter.getCount()==0)
                    {
                        //将myTextView清空
                        myTextView.setText("");
                    }
                }
            }
        });

        //为mySpinner添加OnItemSelextedListener
        mySpinner.setOnItemSelectedListener(new Spinner.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                //将所选mySpinner的值带入myTextView中
                myTextView.setText(parent.getSelectedItem().toString());
            }

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

            }
        });
    }
}

MainActivity

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.asus.gary_0400.MainActivity"
    android:weightSum="1">

    <TextView
        android:id="@+id/myTextView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Gary_动态添加或删除菜单"
        android:textSize="40px" />

    <EditText
        android:id="@+id/myEditText"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:ems="10"
        android:hint="填写添加项"
        android:inputType="textPersonName" />

    <Button
        android:id="@+id/myButton_add"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="添加" />

    <Button
        android:id="@+id/myButton_remove"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="删除" />

    <Spinner
        android:id="@+id/myspinner"
        android:layout_width="match_parent"
        android:layout_height="50px"
        android:layout_weight="0.13" />

</LinearLayout>

activity_main.xml

一、界面布局

　　一个TextView显示框用来显示添加所选项的字符串， EditText作为输入框，两个Button按钮作为”添加“和“删除”对Spinner菜单进行操作

二、实现程序功能

　　1、创建ArrayAdapter对象并将当前Spinner菜单中数据个数多少的值传入

 adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_dropdown_item,allCountries);

        adapter.setDropDownViewResource(
                android.R.layout.simple_spinner_dropdown_item);

　　2、将ArrayAdapter添加到Spinner对象中

// mySpinner = (Spinner)findViewById(R.id.myspinner);
//mySpinner取得Spinner控件对象
mySpinner.setAdapter(adapter);

　　3、实现"添加"按钮功能

  myButton_add.setOnClickListener(new Button.OnClickListener() {

            @Override
            public void onClick(View v) {
                String newCountry = myEditText.getText().toString();
                //先比较添加的值是否存在，不存在才可以添加
                for(int i=0;i<adapter.getCount();i++)
                {
                    if(newCountry.equals(adapter.getItem(i))){
                        return;
                    }
                }

                if(!newCountry.equals(""))
                {
                    //将值添加至adapter
                    adapter.add(newCountry);
                    //取得添加的值的位置
                    int position = adapter.getPosition(newCountry);
                    //将Spinner选择在添加的值的位置
                    mySpinner.setSelection(position);
                    //将myEditText清空
                    myEditText.setText("");
                }
            }
        });

　　4、实现"删除"按钮功能

 myButton_remove.setOnClickListener(new Button.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(mySpinner.getSelectedItem()!=null)
                {
                    //删除mySpinner的值
                    adapter.remove(mySpinner.getSelectedItem().toString());
                    //将myEditText清空
                    myEditText.setText("");
                    if(adapter.getCount()==0)
                    {
                        //将myTextView清空
                        myTextView.setText("");
                    }
                }
            }
        });

　　5、实现TextView控件功能(显示添加进入Spinner中的字符串)

 mySpinner.setOnItemSelectedListener(new Spinner.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                //将所选mySpinner的值带入myTextView中
                myTextView.setText(parent.getSelectedItem().toString());
            }

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

            }
        });