Java类的继承

《super class》
public class Card
{
private String name;

public Card()
{
name = "";
}

public Card(String n)
{
name = n;
}

public String getName()
{
return name;
}

public boolean isExpired()
{
return false;
}

public String toString()
{
return "Card holder: " + name;
}
}
子类
public class IDCard extends Card{
private String idnum;
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｝

public class DriverLicense extends IDCard{
private String year;
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要求以如下形式为IDCard、DriverLicense添加构造函数，每个构造函数应该调用超类构造函数来设置名称
public IDCard(String n, String id)
{
super(n);
idnum = id;
}
如何实现？

public class Card {
private String name;

public Card() {
name = "";
}

public Card(String n) {
name = n;
}

public String getName() {
return name;
}

public boolean isExpired() {
return false;
}

@Override
public String toString() {
return "Card holder: " + name;
}
}

// 子类
class IDCard extends Card {
private String idnum;
public IDCard(String n, String id){
super(n);
this.idnum = id;
}
}

class DriverLicense extends IDCard {
private String year;
public DriverLicense(String n, String id, String year) {
super(n, id);
this.year = year;
}
}

//c1.java classpersona{ privatestringname; publicvoidsetname(stringnewname){ name=newname; } publicstringgetname(){ returnname; } } classstudentaextendspersona{ privatestringdepartment; publicvoidsetdepartment(stringnewdepartment){ department=newdepartment; } publicstringgetdepartment(){ returndepartment; } } classc1{ publicstaticvoidmain(stringargs[]){ studentas1=newstudenta(); s1.setname("张三"); s1.setdepartment("计算机系"); system.out.println("你好，我是"+s1.getname());//你这里写错了不是setname system.out.println("我是"+s1.getdepartment()+"的学生");//不是setdepartment } }