ListView的使用

主要3步骤：

• 创建ListView

• 创建适配器Adapter，和Adapter对应的视图

• 开始渲染数据

效果图：

✅1. 创建ListView

例如现有DemoActivity页面，对于布局文件activity_demo.xml

1.在activity_demo.xml中创建ListView组件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"tools:context=".DemoActivity"><!--创建ListView--><ListViewandroid:id="@+id/lv_list"android:layout_width="match_parent"android:layout_height="wrap_content"android:divider="@null" /></LinearLayout>

2.在DemoActivity页面中获取组件

private static ListView lv_list;//全局声明protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_demo);lv_list = findViewById(R.id.lv_list);//获取视图组件}

✅2. 创建适配器Adapter

1.例如创建一个学生适配器StudentListAdapter,并继承BaseAdapter

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import com.st.bottomnavigation.R;
import com.st.bottomnavigation.bean.Student;import java.util.List;public class StudentListAdapter extends BaseAdapter {private Context mContext;//上下文private List<Student> studentList;//数据//构造方法public StudentListAdapter(Context mContext) {this.mContext = mContext;}//设置数据public void setData( List<Student> studentList){this.studentList = studentList;}//加载新的数据public void addData(List<Student> newData) {studentList.addAll(newData);}@Overridepublic int getCount() {return studentList.size();}@Overridepublic Object getItem(int i) {return studentList.get(i);}@Overridepublic long getItemId(int i) {return i;}@Overridepublic View getView(int position, View convertView, ViewGroup viewGroup) {ViewHolder holder;// 1.推断是不是第一次进来if (convertView == null){convertView = LayoutInflater.from(mContext).inflate(R.layout.item_stu_listview,null);holder = new ViewHolder();holder.stuNo = convertView.findViewById(R.id.stuNo);  //holder.stuName = convertView.findViewById(R.id.stuName);  //convertView.setTag(holder);//标记,能够复用}else {holder = (ViewHolder) convertView.getTag();}//2.填充数据Student student = studentList.get(position);holder.stuNo.setText(student.getStuNo());  //学号holder.stuName.setText(student.getStuName());  //姓名//3.返回convertViewreturn convertView;}//创建ViewHolder,定义item_stu_listview.xml中的组件public final class ViewHolder {TextView stuNo;    //TextView stuName;  //}
}

2.创建实体类Student

public class Student {private String stuNo;private String stuName;public String getStuNo() {return stuNo;}public void setStuNo(String stuNo) {this.stuNo = stuNo;}public String getStuName() {return stuName;}public void setStuName(String stuName) {this.stuName = stuName;}
}

3.创建对应视图文件item_stu_listview.xml，这里可以定义任意类型组件，文本，下拉框，复选框，单选框，图像等等。

<?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="wrap_content"android:background="#eeeeee"android:paddingTop="4dp"android:paddingBottom="4dp"android:paddingLeft="4dp"android:paddingRight="4dp"android:descendantFocusability="blocksDescendants"android:orientation="vertical"><LinearLayoutandroid:id="@+id/ll_item"android:layout_width="match_parent"android:layout_height="wrap_content"android:paddingBottom="10dp"android:paddingTop="10dp"android:paddingLeft="10dp"android:background="@drawable/shape_background_white"android:orientation="vertical"><!--第一行--><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="horizontal"><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:text="学号：" /><TextViewandroid:id="@+id/stuNo"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="" /></LinearLayout><!--第二行--><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="horizontal"><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:text="姓名：" /><TextViewandroid:id="@+id/stuName"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="" /></LinearLayout></LinearLayout></LinearLayout>

对应的shape_background_white.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" ><solid android:color="#FFFFFFFF" /><strokeandroid:width="0dp"android:color="#999999" /><corners android:radius="10dp" /></shape>

✅3. 开始渲染数据

1.造数据，也可以直接从后端数据库获取的数据

   public List<Student> getData(){List<Student> list = new ArrayList<>();for (int i = 0; i < 10; i++) {Student student = new Student();student.setStuName("学生"+i);student.setStuNo(1000+i+"");list.add(student);}return list;}

2.封装渲染方法showStudentListView

    private void showStudentListView(List<Student> studentList) {if(studentListAdapter == null) {//第一次加载studentListAdapter = new StudentListAdapter(this);studentListAdapter.setData(studentList);lv_list.setAdapter(studentListAdapter);// 设置列表视图的适配器}else {// 非第一次，更新数据studentListAdapter.setData(studentList);studentListAdapter.notifyDataSetChanged();}}

3.调用并显示数据

List<Student> studentList = getData();//获取数据
showStudentListView(studentList);//显示数据