BaseAdapter 适配器
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;
}
Demo:
描述：用ListView,BaseAdapter实现多个用户信息展示，根据用户性不同显示不同的性别图片（如下图）
代码如下：
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>
图片文件
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;
}
}