Android BaseAdapter用法

BaseAdapter是一个抽象类，因此要写自已的适配器，段继承此类，并实现以下方法：

@Override
public int getCount() {
    return 0;
}

@Override

public Object getItem(int position) { 
   return null;
}

@Override

public long getItemId(int position) { 
   return 0;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {  
  return null;
}

主界面布局文件：activity_main
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.zy.baseadapter.MainActivity">

    <ListView
        android:id="@+id/user_list_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </ListView>

</RelativeLayout>

//item_user.xml 布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:scaleType="centerInside"
        android:id="@+id/iv_user_img"
        android:layout_width="60dp"
        android:layout_height="60dp" />
    <TextView
        android:id="@+id/tv_user_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/tv_user_age"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/tv_user_sex"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

public class MainActivity extends AppCompatActivity {

    List<UserInfo> userInfos = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
　　　　 //用户数据
        for (int i = 0;i < 30;i++){
            UserInfo userInfo = new UserInfo();
            userInfo.userName = "张" + i;
            userInfo.userAge = i;
            userInfo.userSex = i%2 == 0?"男":"女";
            userInfos.add(userInfo);
        }
　　　　 //listView
        ListView listView = (ListView) findViewById(R.id.user_list_view);
　　　　 //实例化一个适配器
        UserInfoListAdapter userInfoListAdapter = new UserInfoListAdapter();
        listView.setAdapter(userInfoListAdapter);
    }
//    点击屏幕跳转到第二个Activity （点击事件）
//    @Override
//    public boolean onTouchEvent(MotionEvent event) {
//        int action = event.getAction();
//        if(action == MotionEvent.ACTION_DOWN){
//            Intent intent = new Intent(this,MenuActiviy.class);
//            startActivity(intent);
//        }
//        return false;
//    }

    class UserInfoListAdapter extends BaseAdapter{

        @Override
        public int getCount() {
            return userInfos.size();
        }

        @Override
        public Object getItem(int position) {
            return userInfos.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View itemRootView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_user,null);

            TextView userNameView = (TextView) itemRootView.findViewById(R.id.tv_user_name);
            userNameView.setText(userInfos.get(position).userName);

            TextView userAgeView = (TextView) itemRootView.findViewById(R.id.tv_user_age);
            userAgeView.setText(userInfos.get(position).userAge + "");

            TextView userSexView = (TextView) itemRootView.findViewById(R.id.tv_user_sex);
            userSexView.setText(userInfos.get(position).userSex);

            ImageView imageView = (ImageView) itemRootView.findViewById(R.id.iv_user_img);
            if(userInfos.get(position).userSex.equals("男")){
                imageView.setBackgroundResource(R.drawable.man);
            }else if(userInfos.get(position).userSex.equals("女")){
                imageView.setBackgroundResource(R.drawable.woman);
            }
            return itemRootView;
        }
    }
    class UserInfo{
        private String userName;
        private int userAge;
        private String userSex;
    }
}