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ExpandableListView
一、实现效果
ExpandableListView又称可扩展的ListView,简单来说长这个样:
每一个一级布局下面又可以展开二级布局。
二、实现步骤
使用ExpandableListView主要有三个步骤:
- 编写父布局
- 编写子布局
- 适配器的书写
1.编写父布局parent.xml
父布局其实很简单,就是两个并排的TextView,用于展示课程名字和分数:
<?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:background="#F0F3F6" android:orientation="horizontal">
<LinearLayout style="@style/bg_layout" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_margin="1dp" android:clickable="false">
<TextView android:id="@+id/tv_course_name" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="4" android:gravity="center_vertical" android:paddingBottom="8dp" android:paddingLeft="30dp" android:paddingTop="8dp" android:text="课程名" android:textColor="#000" android:textSize="16sp" />
<TextView android:id="@+id/tv_mark" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:gravity="center_vertical" android:paddingBottom="8dp" android:paddingTop="8dp" android:text="等级" android:textColor="#333" android:textSize="16sp" />
</LinearLayout>
</LinearLayout>
2.编写子布局child.xml
子布局就是多个TextView列在一起,用于展示成绩的详细信息:
<?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:background="#F0F0F0" android:orientation="vertical" android:padding="7dp">
<TextView android:id="@+id/tv_xn" style="@style/item_child_grade" />
<TextView android:id="@+id/tv_xq" style="@style/item_child_grade" />
<TextView android:id="@+id/tv_course_code" style="@style/item_child_grade" />
<TextView android:id="@+id/tv_course_nature" style="@style/item_child_grade" />
<TextView android:id="@+id/tv_credit" style="@style/item_child_grade" />
<TextView android:id="@+id/tv_gpa" style="@style/item_child_grade" />
<TextView android:id="@+id/tv_college" style="@style/item_child_grade" />
<TextView android:id="@+id/tv_class" style="@style/item_child_grade" />
<TextView android:id="@+id/tv_teacher" style="@style/item_child_grade" />
</LinearLayout>
3.编写适配器类GradeAdapter
一般适用于ExpandableListView的Adapter都要继承BaseExpandableListAdapter这个类,并且必须重载getGroupView和getChildView这两个最为重要的方法。
-
getGroupView(),返回外面那层布局的视图,也就是各种课程的名称以及分数:
-
getChildView(),返回子布局里面的视图,也就是每门学科的详细信息:
GradeAdapter的详细代码为:
package com.example.edm.adapter;
import android.content.Context;
import androidx.cardview.widget.CardView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseExpandableListAdapter;
import android.widget.ListView;
import android.widget.TextView;
import com.example.edm.R;
import com.example.edm.Student.Grade;
import java.util.List;
public class GradeAdapter extends BaseExpandableListAdapter {
private Context context;
private List<Grade> list;
public GradeAdapter(Context context, List<Grade> list) {
this.context = context;
this.list = list;
}
@Override
//获取分组个数
public int getGroupCount() {
return list.size();
}
@Override
//分组中子选项个数为1
public int getChildrenCount(int i) {
return 1;
}
@Override
//获取指定分组数据
public Object getGroup(int i) {
return list.get(i);
}
@Override
//获取指定子选项数据
public Object getChild(int i, int j) {
return null;
}
@Override
//获取指定分组的id
public long getGroupId(int i) {
return i;
}
@Override
public long getChildId(int i, int i1) {
return i1;
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public View getGroupView(int i, boolean b, View convertView, ViewGroup viewGroup) {
View view;
GroupHolder groupHolder;
if (convertView == null) {
//父布局
view = View.inflate(context, R.layout.parent, null);
groupHolder = new GroupHolder();
groupHolder.tv_course_name = view.findViewById(R.id.tv_course_name); //课程名
groupHolder.tv_mark = view.findViewById(R.id.tv_mark); //成绩
view.setTag(groupHolder);
} else {
view = convertView;
groupHolder = (GroupHolder) view.getTag();
}
groupHolder.tv_course_name.setText(list.get(i).getCourse_name());
groupHolder.tv_mark.setText(list.get(i).getMark());
return view;
}
public View getChildView(int i, int i1, boolean b, View convertView, ViewGroup viewGroup) {
View view;
ChildHolder childHolder;
if (convertView == null) {
view = View.inflate(context, R.layout.child, null);
childHolder = new ChildHolder();
childHolder.tv_xn = view.findViewById(R.id.tv_xn);
childHolder.tv_xq = view.findViewById(R.id.tv_xq);
childHolder.tv_course_code = view.findViewById(R.id.tv_course_code);
childHolder.tv_course_nature = view.findViewById(R.id.tv_course_nature);
childHolder.tv_credit = view.findViewById(R.id.tv_credit);
childHolder.tv_gpa = view.findViewById(R.id.tv_gpa);;
childHolder.tv_college = view.findViewById(R.id.tv_college);
childHolder.tv_class = view.findViewById(R.id.tv_class);
childHolder.tv_teacher = view.findViewById(R.id.tv_teacher);
view.setTag(childHolder);
} else {
view = convertView;
childHolder = (ChildHolder) view.getTag();
}
childHolder.tv_xn.setText("学年:" + list.get(i).getXn());
childHolder.tv_xq.setText("学期:" + list.get(i).getXq());
childHolder.tv_course_code.setText("课程代码:" + list.get(i).getCourse_code());
childHolder.tv_course_nature.setText("课程性质:" + list.get(i).getCourse_nature());
childHolder.tv_credit.setText("学分:" + list.get(i).getCredit());
childHolder.tv_gpa.setText("绩点:" + list.get(i).getGpa());
childHolder.tv_college.setText("开课学院:" + list.get(i).getCollege());
childHolder.tv_class.setText("教学班:" + list.get(i).getClass_());
childHolder.tv_teacher.setText("任课教师:" + list.get(i).getTeacher());
return view;
}
@Override
public boolean isChildSelectable(int i, int i1) {
return false;
}
static class GroupHolder {
TextView tv_course_name;
TextView tv_mark;
}
static class ChildHolder {
TextView tv_xn;
TextView tv_xq;
TextView tv_course_code;
TextView tv_course_nature;
TextView tv_credit;
TextView tv_gpa;
TextView tv_college;
TextView tv_class;
TextView tv_teacher;
}
}
三、解析适配器类
适配器类有一个私有列表变量,列表的类型为Grade,Grade是一个封装好的关于成绩信息的类,Grade.java代码为:
package com.example.edm.Student;
public class Grade {
private String xn; //学年
private String xq; //学期
private String course_code; //课程代码
private String course_name; //课程名字
private String course_nature; //课程性质
private String credit; //学分
private String gpa; //绩点
private String mark; //分数
private String grade_nature; //成绩性质
private String class_; //教学班
private String teacher; //老师
public String getXn() {
return xn;
}
public void setXn(String xn) {
this.xn = xn;
}
public String getXq() {
return xq;
}
public void setXq(String xq) {
this.xq = xq;
}
public String getCourse_code() {
return course_code;
}
public void setCourse_code(String course_code) {
this.course_code = course_code;
}
public String getCourse_name() {
return course_name;
}
public void setCourse_name(String course_name) {
this.course_name = course_name;
}
public String getCourse_nature() {
return course_nature;
}
public void setCourse_nature(String course_nature) {
this.course_nature = course_nature;
}
public String getCredit() {
return credit;
}
public void setCredit(String credit) {
this.credit = credit;
}
public String getGpa() {
return gpa;
}
public void setGpa(String gpa) {
this.gpa = gpa;
}
public String getMark() {
return mark;
}
public void setMark(String mark) {
this.mark = mark;
}
public String getCollege() {
return college;
}
public void setCollege(String college) {
this.college = college;
}
public String getClass_() {
return class_; }
public void setClass_(String class_) {
this.class_ = class_;
}
public String getTeacher() {
return teacher; }
public void setTeacher(String teacher) {
this.teacher = teacher;
}
}
里面包含设置和获取每种信息的方法。
getGroupView和getChildView两个方法我举getGroupView来详细讲解:
public View getGroupView(int i, boolean b, View convertView, ViewGroup viewGroup) {
View view;
GroupHolder groupHolder;
if (convertView == null) {
//父布局
view = View.inflate(context, R.layout.parente, null);
groupHolder = new GroupHolder();
groupHolder.tv_course_name = view.findViewById(R.id.tv_course_name); //课程名
groupHolder.tv_mark = view.findViewById(R.id.tv_mark); //成绩
view.setTag(groupHolder);
} else {
view = convertView;
groupHolder = (GroupHolder) view.getTag();
}
groupHolder.tv_course_name.setText(list.get(i).getCourse_name());
groupHolder.tv_mark.setText(list.get(i).getMark());
return view;
}
view = View.inflate(context, R.layout.parent, null);
这句代码作用为设置外面布局为我们编写的parent.xml, 但现在里面还没有数据。
我们定义了一个GroupHolder来保存这些数据:
static class GroupHolder {
TextView tv_course_name;
TextView tv_mark;
}
里面包含了父布局的所有数据属性,我们在getGroupView中初始化这些变量,这些变量的数据都保存在list里面,都在我们初始化GradeAdapter时传进来。
groupHolder = new GroupHolder();
groupHolder.tv_course_name = view.findViewById(R.id.tv_course_name); //课程名
groupHolder.tv_mark = view.findViewById(R.id.tv_mark); //成绩
设置groupHolder的各种值:
groupHolder.tv_course_name.setText(list.get(i).getCourse_name());
groupHolder.tv_mark.setText(list.get(i).getMark());
附上主界面GradeActivity代码:
String year = schoolYear.getText().toString();
String semester_ = semester.getText().toString();
String course_nature = course.getText().toString();
if(year.equals("学年")) {
ToastUtil.showMessage(this,"请选择学年!");
}else if(semester_.equals("学期")) {
ToastUtil.showMessage(this, "请选择学期!");
}else if(course_nature.equals("课程性质")) {
ToastUtil.showMessage(this, "请选择课程性质!");
}else {
//开始查询成绩并显示
try {
String year_ = year.substring(0, 4);
ArrayList<Grade> list = connectJWGL.getStudentGrade(Integer.parseInt(year_), Integer.parseInt(semester_), course_nature);
if (list.size() == 0) {
ToastUtil.showMessage(this, "没有查到记录!");
}else {
for(int i = 0; i < list.size(); ++i) {
list.get(i).setXn(year);
list.get(i).setXq(semester_);
}
expand_lv.setAdapter(new GradeAdapter(this, list));
}
} catch (Exception e) {
e.printStackTrace();
}
}
这一步涉及到一些网络爬虫的知识,大家在用这个demo的时候只要自己定义一个list,然后在里面手动添加一些数据就好了。核心代码为:
expand_lv.setAdapter(new GradeAdapter(this, list));
list里面已经包含了所有我们需要的信息。
布局代码也很简单,只要有一个ExpandableListView就好了:
<ExpandableListView android:id="@+id/expand_lv" android:layout_margin="1dp" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#F0F3F6" android:divider="@null">
</ExpandableListView>
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