Android中使用Spinner实现下拉列表功能

//(layout)activity_main<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context="com.test.spinner.MainActivity"> <LinearLayout  android:layout_width="match_parent"  android:layout_height="wrap_content"  android:orientation="horizontal">  <TextView   android:textSize="20sp"   android:layout_margin="10dp"   android:layout_width="wrap_content"   android:layout_height="wrap_content"   android:text="今年的常规赛MVP："/>  <TextView   android:id="@+id/text"   android:textSize="20sp"   android:layout_marginTop="10dp"   android:layout_width="wrap_content"   android:layout_height="wrap_content"/> </LinearLayout> <Spinner  android:visibility="gone"  android:id="@+id/spinner"  android:layout_marginLeft="10dp"  android:layout_width="wrap_content"  android:layout_height="wrap_content"> </Spinner></LinearLayout>-------------------------------------------------------------------//(layout)item<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="horizontal"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:gravity="center_vertical"> <ImageView  android:id="@+id/imageView"  android:layout_width="80dp"  android:layout_height="80dp"/> <TextView  android:id="@+id/textView"  android:layout_marginLeft="20dp"  android:layout_width="wrap_content"  android:layout_height="wrap_content"/></LinearLayout>

//MainActivityimport android.content.Context;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.widget.AdapterView;import android.widget.ArrayAdapter;import android.widget.SimpleAdapter;import android.widget.Spinner;import android.widget.TextView;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import static com.test.spinner.R.id.simpleAdapter;public class MainActivity extends AppCompatActivity { private Context mContext = MainActivity.this; private Spinner mSpinner; private ArrayAdapter<String> mArrayAdapter; private TextView mTextView; private SimpleAdapter mSimpleAdapter; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  initView();  initData(); } private void initView(){  mSpinner = (Spinner) findViewById(R.id.spinner);  mTextView = (TextView) findViewById(R.id.text); } private void initData(){  // 设置数据集  List<String> list = new ArrayList<>();  list.add("哈登");  list.add("莱昂纳德");  list.add("詹姆斯");  list.add("威斯布鲁克");  List<Map<String ,Object>> maps = new ArrayList<>();  int[] icon = {R.mipmap.pic1 , R.mipmap.pic2, R.mipmap.pic3, R.mipmap.pic4};  String[] iconName = {"哈登" , "莱昂纳德" , "詹姆斯" , "威斯布鲁克"};  // 设置适配器  mArrayAdapter = new ArrayAdapter<>(mContext ,    android.R.layout.simple_spinner_item , list);  mArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);  mSimpleAdapter = new SimpleAdapter(mContext,    maps , R.layout.item , new String[]{"image" , "text"} , new int[]{R.id.imageView ,R.id.textView});  for(int i = 0 ; i < icon.length ; i++){   Map<String ,Object> map = new HashMap<>();   map.put("image", icon[i]);   map.put("text" , iconName[i]);   maps.add(map);  } } @Override public boolean onCreateOptionsMenu(Menu menu) {  getMenuInflater().inflate(R.menu.main , menu);  return true; } @Override public boolean onOptionsItemSelected(MenuItem item) {  switch (item.getItemId()){   case R.id.arrayAdapter:    mSpinner.setVisibility(View.VISIBLE);    mSpinner.setAdapter(mArrayAdapter);    // 设置监听器    mSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {     @Override     public void onItemSelected(AdapterView<?> adapterView, View view, int position, long id) {      mTextView.setText(mArrayAdapter.getItem(position));     }     @Override     public void onNothingSelected(AdapterView<?> adapterView) {     }    });    break;   case simpleAdapter:    mSpinner.setVisibility(View.VISIBLE);    mSpinner.setAdapter(mSimpleAdapter);    // 设置监听器    mSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {     @Override     public void onItemSelected(AdapterView<?> adapterView, View view, int position, long id) {      mTextView.setText(mSimpleAdapter.getItem(position)+"");     }     @Override     public void onNothingSelected(AdapterView<?> adapterView) {     }    });    break;   default:    break;  }  return super.onOptionsItemSelected(item); }}