android中添加级联更新的下拉菜单

package com.silei.day04_spinnercity;

import android.app.Activity;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.widget.AdapterView;

import android.widget.AdapterView.OnItemSelectedListener;

import android.widget.ArrayAdapter;

import android.widget.Spinner;

public class MainActivity extends Activity {

Spinner mSpinner1;

ArrayAdapter<String> mAdapterSP1;

String[] mDataSP1;

Spinner mSpinner2;

ArrayAdapter<String> mAdapterSP2;

String[] mDataSP2;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

initFind();

initSPData1();

initSPEvent1();

//initSPdata2();

}

private void initSPdata2() {

mDataSP2=new String[]{};

//分配一个数据长度为0的字符串数组给变量

mAdapterSP2=new ArrayAdapter<String>(

getApplicationContext(),

android.R.layout.simple_spinner_dropdown_item);

//跟上一个的区别，动态生成的，动态更新

mSpinner2.setAdapter(mAdapterSP2);

}

private void initSPEvent1() {

// 组件事件

mSpinner1.setOnItemSelectedListener(new OnItemSelectedListener() {

@Override

public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

int cityIndex = position;

//准备适配器，第一种方法，是可以的。

mDataSP2 = readCity12(cityIndex);

mAdapterSP2 = new ArrayAdapter<String>(MainActivity.this,

android.R.layout.simple_spinner_dropdown_item,

mDataSP2);

mSpinner2.setAdapter(mAdapterSP2);

//不管是第一次还是后续的，先清数据源的数据

mAdapterSP2.clear();

//读取数据源的数据

mDataSP2 = readCity12(cityIndex);

//设置适配器的数据源

mAdapterSP2.addAll(mDataSP2);*/

}

@Override

public void onNothingSelected(AdapterView<?> parent) {

// TODO Auto-generated method stub

}

});

}

private String[] readCity1() {

String[] provinces = new String[] { "北京", "河南" };

return provinces;

}

// 读出指定省下面的城市

private String[] readCity12(int cityIndex) {

String[][] cities = new String[][] {

{ "海淀", "朝阳","昌平" },

{ "郑州", "新乡" ,"洛阳","信阳"} };

return cities[cityIndex];

}

private void initSPData1() {

// 读取数据源

mDataSP1 = readCity1();

// 实例化适配器

mAdapterSP1 = new ArrayAdapter<String>(MainActivity.this,

android.R.layout.simple_spinner_dropdown_item,

mDataSP1);

// 设置适配器

mSpinner1.setAdapter(mAdapterSP1);

}

private void initFind() {

mSpinner1 = (Spinner) findViewById(R.id.spinner1);

mSpinner2 = (Spinner) findViewById(R.id.spinner2);

}

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