一手遮天 Android - view（选择类）: Spinner 通过自定义 BaseAdapter 显示数据
一手遮天 Android - view（选择类）: Spinner 通过自定义 BaseAdapter 显示数据
示例如下:
/view/selection/SpinnerDemo5.java
/**
* Spinner - 列表选择框控件（演示如何通过自定义 BaseAdapter 显示数据）
*/
package com.webabcd.androiddemo.view.selection;
import android.content.Context;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import com.webabcd.androiddemo.R;
import java.util.ArrayList;
import java.util.List;
public class SpinnerDemo5 extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
private Spinner mSpinner1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_selection_spinnerdemo5);
mSpinner1 = findViewById(R.id.spinner1);
// 选择项发生变化时触发的事件（注：第一次加载时也会触发此事件）
mSpinner1.setOnItemSelectedListener(this);
sample();
}
private void sample() {
// 构造数据
List<MyData> myDataList = new ArrayList<MyData>();
myDataList.add(new MyData(R.drawable.img_sample_son, "中国", "我是中国"));
myDataList.add(new MyData(R.drawable.img_sample_son, "美国", "我是美国"));
myDataList.add(new MyData(R.drawable.img_sample_son, "日本", "我是日本"));
// 实例化自定义的 BaseAdapter
MyAdapter myAdapter = new MyAdapter(myDataList, this);
mSpinner1.setAdapter(myAdapter);
}
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
// parent 就是 ListView
// view 就是被点击的 item
// position 就是被点击的 item 的索引位置
// id 就是被点击的 item 的 id（通过调用 BaseAdapter 的 getItemId(int position) 来获取此 id）
// 调用 BaseAdapter 的 getItem(int position)
// MyData myData = (MyData)parent.getAdapter().getItem(position);
// 与上面的代码其实是一样的，会调用 BaseAdapter 的 getItem(int position)
MyData myData = (MyData)parent.getItemAtPosition(position);
Toast.makeText(this,String.format("click position:%d, id:%d, data:%s", position, id, myData.getName()),Toast.LENGTH_SHORT).show();
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
// 自定义实体类
class MyData {
private int _logoId;
private String _name;
private String _comment;
public MyData() {
}
public MyData(int logoId, String name, String comment) {
this._logoId = logoId;
this._name = name;
this._comment = comment;
}
public int getLogoId() {
return _logoId;
}
public String getName() {
return _name;
}
public String getComment() {
return _comment;
}
public void setLogoId(int logoId) {
this._logoId = logoId;
}
public void setName(String name) {
this._name = name;
}
public void setComment(String comment) {
this._comment = comment;
}
}
// 自定义 BaseAdapter
class MyAdapter extends BaseAdapter {
private List<MyData> _myDataList;
private Context _context;
public MyAdapter(List<MyData> myDataList, Context context) {
this._myDataList = myDataList;
this._context = context;
}
// 需要呈现的 item 的总数
@Override
public int getCount() {
return _myDataList.size();
}
// 返回指定索引位置的 item 的对象
@Override
public Object getItem(int position) {
return _myDataList.get(position);
}
// 返回指定索引位置的 item 的 id
@Override
public long getItemId(int position) {
return position;
}
/*
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = LayoutInflater.from(_context).inflate(R.layout.item_view_selection_spinnerdemo5,parent,false);
ImageView imgLogo = (ImageView) view.findViewById(R.id.imgLogo);
TextView txtName = (TextView) view.findViewById(R.id.txtName);
TextView txtComment = (TextView) view.findViewById(R.id.txtComment);
imgLogo.setBackgroundResource(_myDataList.get(position).getLogoId());
txtName.setText(_myDataList.get(position).getName());
txtComment.setText(_myDataList.get(position).getComment());
return view;
}
*/
// 每构造一个 item 就会调用一次 getView() 来获取这个 item 的 view
// 数据量不大的话就可以像上面那样写，数量大的话则可以像下面这样写
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
if (convertView == null) {
convertView = LayoutInflater.from(_context).inflate(R.layout.item_view_selection_spinnerdemo5, parent, false);
holder = new ViewHolder();
holder.imgLogo = (ImageView) convertView.findViewById(R.id.imgLogo);
holder.txtName = (TextView) convertView.findViewById(R.id.txtName);
holder.txtComment = (TextView) convertView.findViewById(R.id.txtComment);
convertView.setTag(holder); // 将 holder 保存到 convertView 中
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.imgLogo.setBackgroundResource(_myDataList.get(position).getLogoId());
holder.txtName.setText(_myDataList.get(position).getName());
holder.txtComment.setText(_myDataList.get(position).getComment());
return convertView;
}
class ViewHolder {
ImageView imgLogo;
TextView txtName;
TextView txtComment;
}
}
}
/layout/activity_view_selection_spinnerdemo5.xml
<?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:id="@+id/spinner1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
/layout/item_view_selection_spinnerdemo5.xml
<?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="horizontal">
<ImageView
android:id="@+id/imgLogo"
android:layout_width="64dp"
android:layout_height="64dp" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/txtName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#1D1D1D"
android:textSize="24sp" />
<TextView
android:id="@+id/txtComment"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#B4B4B4"
android:textSize="14sp" />
</LinearLayout>
</LinearLayout>
