只能得到地址值！姓名、性别的值得不到！

Question

只能得到地址的值。
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/*
*学生类的重载
*/public class StudentOverloading
{
public static void main(String[] args)
{
Student tom = new Student("Tom");
tom.setStudentSex("man");
tom.setStudentAddress("America");
System.out.println(tom.toString());
}
}class Student
{
private String strName = "";
private String strNumber = "";
private String strSex = "";
private String strBirthday = "";
private String strSpeciality = "";
private String strAddress = "";

public Student()
{}

public Student(String name)
{
this(name, "");
}

public Student(String name, String number)
{
strName = name;
strNumber = number;
}

public String getStudentName()
{
return strName;
}

public String getStudentNumber()
{
return strNumber;
}

public void setStudentSex(String sex)
{
strSex = sex;
}

public String getStudentSex()
{
return strSex;
}

public void setStudentBirthday(String birthday)
{
strBirthday = birthday;
}

public String getStudentBirthday()
{
return strBirthday;
}

public void setStudentSpeciality(String speciality)
{
strSpeciality = speciality;
}

public String getStudentSpeciality()
{
return strSpeciality;
}

public void setStudentAddress(String address)
{
strAddress = address;
}

public String getStudentAddress()
{
return strAddress;
}

public String toString()
{
String information = "姓名:" + strName + ", 学号:" + strNumber;
if(!strSex.equals(""))
information = "性别:" + strSex;
if(!strSpeciality.equals(""))
information = "专业:" + strSpeciality;
if(!strBirthday.equals(""))
information = "出生日期:" + strBirthday;
if(!strAddress.equals(""))
information = "地址:" + strAddress;
return information;
}
}

Answer 1

information += "xx:" + xx;
           ===

Answer 2

public String toString()
    {
        String information = "姓名:" + strName + ", 学号:" + strNumber;
        if(!strSex.equals(""))
            information = "性别:" + strSex;
        if(!strSpeciality.equals(""))
            information = "专业:" + strSpeciality;
        if(!strBirthday.equals(""))
            information = "出生日期:" + strBirthday;
        if(!strAddress.equals(""))
            information = "地址:" + strAddress;
        return information;
    }
上述方法写的有问题~~~
可以改为如下~~    public String toString()
    {
        String information = "姓名:" + strName + ", 学号:" + strNumber;
        if(!strSex.equals(""))
            information = information + ", 性别:" + strSex;
        if(!strSpeciality.equals(""))
            information = information + ", 专业:" + strSpeciality;
        if(!strBirthday.equals(""))
            information = information + ", 出生日期:" + strBirthday;
        if(!strAddress.equals(""))
            information = information + ", 地址:" + strAddress;
        return information;
    }

Answer 3

if(!strSex.equals(""))
information =information + "性别:" + strSex;
if(!strSpeciality.equals(""))
information =information + "专业:" + strSpeciality;
if(!strBirthday.equals(""))
information =information + "出生日期:" + strBirthday;
if(!strAddress.equals(""))
information =information + "地址:" + strAddress;