JAVA8--List.stream().collect-蒲公英云

JAVA8--List.stream().collect

package mypack;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
public class Test
{
    public static void main(String[] args) throws ParseException
    {
        Student s1 = new Student("1", "S1", 10);
        Student s2 = new Student("1", "S1", 10);
        Student s3 = new Student("1", "S1", 10);
        Student s4 = new Student("2", "S2", 20);
        Student s5 = new Student("2", "S2", 20);
        Student s6 = new Student("2", "S2", 20);
        Student s7 = new Student("3", "S3", 30);
        Student s8 = new Student("3", "S3", 30);
        Student s9 = new Student("4", "S4", 40);
        Student s10 = new Student("4", "S4", 40);
        List<Student> sList = new ArrayList<Student>();
        sList.add(s1);
        sList.add(s2);
        sList.add(s3);
        sList.add(s4);
        sList.add(s5);
        sList.add(s6);
        sList.add(s7);
        sList.add(s8);
        sList.add(s9);
        sList.add(s10);
        Map<ParentStudent, List<Student>> sMap = sList.stream().collect(Collectors.groupingBy(student -> new ParentStudent(student.getId())));
        sMap.forEach((key, value) -> {
            System.out.print("id:" + key.getId() + "====");
            for(Student s : value)
            {
                System.out.print("name:" + s.getName() + ",");
            }
            System.out.println("");
        });
    }
}
class ParentStudent extends SupperStudent
{
    String id;
    public ParentStudent(String sid)
    {
        this.id = sid;
    }
    @Override
    public int hashCode()
    {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((id == null) ? 0 : id.hashCode());
        return result;
    }
    @Override
    public boolean equals(Object obj)
    {
        if(this == obj)
            return true;
        if(obj == null)
            return false;
        if(getClass() != obj.getClass())
            return false;
        ParentStudent other = (ParentStudent)obj;
        if(id == null)
        {
            if(other.id != null)
                return false;
        }
        else if(!id.equals(other.id))
            return false;
        return true;
    }
    public String getId()
    {
        return id;
    }
    public void setId(String id)
    {
        this.id = id;
    }
}
class SupperStudent
{
    private String sex;
    public String getSex()
    {
        return sex;
    }
    public void setSex(String sex)
    {
        this.sex = sex;
    }
}
class Student
{
    String id;
    String name;
    int age;
    public Student(String sid)
    {
        this.id = sid;
    }
    public Student(String sid, String sname, int sage)
    {
        this.id = sid;
        this.name = sname;
        this.age = sage;
    }
    public String getId()
    {
        return id;
    }
    public void setId(String id)
    {
        this.id = id;
    }
    public String getName()
    {
        return name;
    }
    public void setName(String name)
    {
        this.name = name;
    }
    public int getAge()
    {
        return age;
    }
    public void setAge(int age)
    {
        this.age = age;
    }
}