teststudent.java

我在学习JAVA的讲义

class Name
{   private String first;                  //例如，“William”
    private String middle;	//例如，“Jefferson”
    private String last;	                  //例如，“Clinton”

    Name( )		//缺省构造函数
    {
    }

    Name(String first,String last)
    {   this.first=first;
        this.last=last;
    }

    Name(String first,String middle,String last)
    {   this(first,last);
        this.middle=middle;
    }

    String first( )
    {   return first;
    }

    String middle( )
    {   return middle;
    }

    String last( )
    {   return last;
    }

    void setFirst(String first)
    {   this.first=first;
    }

    void setMiddle(String middle)
    {   this.middle=middle;
    }

    void setLast(String last)
    {   this.last=last;
    }

    public String toString( )
    {   String s=new String( );
        if(first!=null) s+=first+" ";
        if(middle!=null) s+=middle+" ";
        if(last!=null) s+=last+" ";
        return s.trim( );                   //去掉前后空格
    }
}

class Person
{   protected Name name;
    protected char sex;	//'M'或'F'
    protected String id;	//社会保险号

    Person(Name name,char sex)
    {   this.name=name;
        this.sex=sex;
    }

    Person(Name name,char sex,String id)
    {   this.name=name;
        this.sex=sex;
        this.id=id;
    }

    Name name( )
    {   return name;
    }

    char sex( )
    {   return sex;
    }

    String id( )
    {   return id;
    }

    void setId(String id)
    {   this.id=id;
    }

    public String toString( )
    {   String s=new String(name+"(sex:"+sex);
        if(id!=null) 
            s+=";id:"+id;
        s+=")";
        return s;
    }
}

class Student extends Person
{   protected int credits;	//获得的课时数
    protected double gpa;	//平均的学分

    Student(Name name,char sex,int credits,double gpa)
    {   super(name,sex);	//调用Person类的构造方法
        this.credits=credits;
        this.gpa=gpa;
    }

    int credits( )
    {   return credits;
    }

    double gpa( )
    {   return gpa;
    }

    public String toString( )
    {   String s;
        s=new String(super.toString( ));	//调用Person.toString( )
        s+="\n\tcredits: "+credits;
        s+="\n\tgpa: "+gpa;
        return s;
    }
}

class TestStudent
{   public static void main(String args[ ])
    {   Name annsName=new Name("Ann","Baker");
        Student ann=new Student(annsName,'F',16,3.5);
        System.out.println("ann: "+ann);
    }
}