帮忙下看程序错在哪里,红色的有错,还请大家指教下,说明为什么错,先谢谢大家了

public class Name
{ private String firstname;
private char mi;
private String lastname;
public Name()
{ this ("Jill",'s',"Barr");
}
public String Name(String firstname,char mi,String lastname)
{ this.firstname = firstname;
this.mi = mi;
this.lastname = lastname;
}
public String getFirstname()
{ return firstname;
}
public void setFirstname(String firstname)
{ this.firstname = firstname;
}
public char getMi()
{ return mi;
}
public void setMi(char mi)
{ this.mi = mi;
}
public String getLastname()
{ return lastname;
}
public void setLastname(String lastname)
{ this.lastname = lastname;
}
public String getFullname()
{ return firstname + ' ' + mi + ' ' + lastname;
}
}

public class A1
{ public static void main(String[] args)
{ Name name = new Name("John",'D',"Smith");
System.out.println(name);
}
}

你得用带参的构造函数!你用this();也是调用类的构造函数,你里面没有带三个参数的构造函数,所以会报错

我把这个
public Name()
{ this ("Jill",'s',"Barr");
}
去掉后,但还是出错,应该怎么改啊

public String Name(String firstname,char mi,String lastname)
这个构造写错了 构造不写返回值地。。。
改为
public Name(String firstname,char mi,String lastname)

你这是对构造方法的重载,不能有返回值.....

对
构造函数不能返回值

而且你的代码
public Name()
{ this ("Jill",'s',"Barr");
}
赋值不对
public Name(){
this.firstname="Jill";
this.mi ='s';
this.lastname ="Barr";
}

哦......this关键字还有这样的用法啊.

[CODE]public String Name(String firstname,char mi,String lastname)//构造方法 没有返回值 也不是void类型
{ this.firstname = firstname;
this.mi = mi;
this.lastname = lastname
[/CODE]
应该为
[CODE]
public Name( firstname,char mi,String lastname)
{...
...
}
[/CODE]
另外 this 关键字用来调用类内的字段和方法 它指带类对象本身

LZ this指针有这种用法吗 6楼的倒是常用