主布局、适配器、item布局与内容
- 主布局
- 适配器
public class spinnerDropDownActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
// 数据
List names = Arrays.asList(new String[]{"火星", "地球","金星","水星"});
private Spinner spinnerId;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_spinner_drop_down);
initView();
// 适配器
ArrayAdapter adapter = new ArrayAdapter<>(this, R.layout.item_view, names);
spinnerId.setAdapter(adapter);
spinnerId.setSelection(0);
spinnerId.setOnItemSelectedListener(this);
}
private void initView() {
spinnerId = (Spinner) findViewById(R.id.spinner_id);
}
@Override
public void onItemSelected(AdapterView adapterView, View view, int i, long l) {
Log.e(TAG, "onItemSelected: int " + i + " long:" + l);
Toast.makeText(this,names.get(i),Toast.LENGTH_LONG).show();
}
@Override
public void onNothingSelected(AdapterView adapterView) {
}
}
- item布局
SimpleAdapter
simpleAdapter与ArrayAdapter类似，不同之处在于传入参数 不同：
package com.example.viewpager;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.SimpleAdapter;
import android.widget.Spinner;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MySimpleAdapter extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
private Spinner spinnerId;
// 定义下拉列表需要显示的行星图标数组
private static final int[] iconArray = {
R.drawable.shuixing, R.drawable.jinxing, R.drawable.diqiu,
R.drawable.huoxing, R.drawable.muxing, R.drawable.tuxing
};
// 定义下拉列表需要显示的行星名称数组
private static final 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_my_simple_adapater);
initView();
List> list = new ArrayList<>();
for (int i = 0; i < iconArray.length; i++) {
HashMap map = new HashMap<>();
map.put("icon", iconArray[i]);
map.put("name", starArray[i]);
list.add(map);
}
// 这是simpleAdapter 的传入参数 from指的是数据 to指的是视图对应id
SimpleAdapter simpleAdapter = new SimpleAdapter(this, list,
R.layout.simple_item,
new String[]{"icon", "name"},
new int[]{R.id.icon, R.id.tv_id});
spinnerId.setAdapter(simpleAdapter);
spinnerId.setPrompt("请选择：");
spinnerId.setSelection(0);
spinnerId.setOnItemSelectedListener(this);
}
private void initView() {
spinnerId = (Spinner) findViewById(R.id.spinner_id);
}
@Override
public void onItemSelected(AdapterView parent, View view, int position, long id) {
Toast.makeText(this, "选择了 " + starArray[position], Toast.LENGTH_SHORT).show();
}
@Override
public void onNothingSelected(AdapterView parent) {
}
}
BaseAdapter
四个要素：主布局、实现的BaseAdapter、数据类以及数据、item布局、主程序
- 主布局：
- 实现的BaseAdapter：
public class PlanetBaseAdapter extends BaseAdapter {
private Context context;
private List planetList;
public PlanetBaseAdapter(Context context,List planetList){
this.context = context;
this.planetList = planetList;
}
// count返回的是数据的总数
@Override
public int getCount() {
return planetList.size();
}
// 返回的是对应位置的数据
@Override
public Object getItem(int position) {
return planetList.get(position);
}
// 返回的是item对应的ID,可以设置为position
@Override
public long getItemId(int position) {
return position;
}
// 返回的是item页面的View
@Override
public View getView(int position, View convertView, ViewGroup parent) {
convertView = LayoutInflater.from(context).inflate(R.layout.item_layout, null);
ImageView imageView = (ImageView) convertView.findViewById(R.id.icon);
TextView tv_desc = (TextView) convertView.findViewById(R.id.tv_desc);
TextView tv_name = (TextView) convertView.findViewById(R.id.tv_name);
Planet planet = planetList.get(position);
imageView.setImageResource(planet.image);
tv_name.setText(planet.name);
tv_desc.setText(planet.desc);
return convertView;
}
}
- 数据类与数据：
public class Planet {
public int image; // 行星图标
public String name; // 行星名称
public String desc; // 行星描述
public Planet(int image, String name, String desc) {
this.image = image;
this.name = name;
this.desc = desc;
}
private static int[] iconArray = {R.drawable.shuixing, R.drawable.jinxing, R.drawable.diqiu,
R.drawable.huoxing, R.drawable.muxing, R.drawable.tuxing};
private static String[] nameArray = {"水星", "金星", "地球", "火星", "木星", "土星"};
private static String[] descArray = {
"水星是太阳系八大行星最内侧也是最小的一颗行星，也是离太阳最近的行星",
"金星是太阳系八大行星之一，排行第二，距离太阳0.725天文单位",
"地球是太阳系八大行星之一，排行第三，也是太阳系中直径、质量和密度最大的类地行星，距离太阳1.5亿公里",
"火星是太阳系八大行星之一，排行第四，属于类地行星，直径约为地球的53%",
"木星是太阳系八大行星中体积最大、自转最快的行星，排行第五。它的质量为太阳的千分之一，但为太阳系中其它七大行星质量总和的2.5倍",
"土星为太阳系八大行星之一，排行第六，体积仅次于木星"
};
public static List getDefaultList() {
List planetList = new ArrayList();
for (int i = 0; i < iconArray.length; i++) {
planetList.add(new Planet(iconArray[i], nameArray[i], descArray[i]));
}
return planetList;
}
}
- item布局：
- 主程序
public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
private Spinner spinnerId;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
PlanetBaseAdapter planetBaseAdapter = new PlanetBaseAdapter(this, Planet.getDefaultList());
spinnerId.setAdapter(planetBaseAdapter);
spinnerId.setSelection(0);
spinnerId.setOnItemSelectedListener(this);
}
private void initView() {
spinnerId = (Spinner) findViewById(R.id.spinner_id);
}
@Override
public void onItemSelected(AdapterView parent, View view, int position, long id) {
Toast.makeText(this,"你选择了：" + Planet.getDefaultList().get(position).name,Toast.LENGTH_SHORT).show();
}
@Override
public void onNothingSelected(AdapterView parent) {
}
}
