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[ 本帖最后由 base 于 2010-7-14 20:47 编辑 ]

流浪的流氓

results is an array !!! when you use sysout print an array, it will print out the memory pointer, it is not 乱码


  public float[] studentresult()
     {
             int i;
             System.out.println("Please enter the result of four assignment.");
             for(i=0; i<4; i++)
             {
                     results = console.nextFloat();    is this working?? assign a Float value to an array ??
              }
            return results;        
     }

[ 本帖最后由 流浪的流氓 于 2007-9-21 11:00 编辑 ]

19st9

in OO, there is a concept of data hiding, you have created the getter and setter, why do you still acess the member instance straight away outside the class?

kawara

原帖由 19st9 于 2007-9-22 10:33 发表
in OO, there is a concept of data hiding, you have created the getter and setter, why do you still acess the member instance straight away outside the class?

Correct. Officially  it is one aspect of Encapsulation,the other aspect is method hiding

伐木者

Never use such a method called defaultconstructor(). The proper way:

In student class:
public Student(String firstName, String lastName) {
  this.firstName = firstName;
  this.surName = lastName;
}

In driver class:
  Student svenL = new Student("Sven", "Liao");

To print out the contents of an array, you have to loop through it, or use Arrays.toString()

[ 本帖最后由 伐木者 于 2007-9-22 14:23 编辑 ]

伐木者

原帖由 19st9 于 2007-9-22 10:33 发表
in OO, there is a concept of data hiding, you have created the getter and setter, why do you still acess the member instance straight away outside the class?

Right, the program should have made all the instance variables private.

[ 本帖最后由 伐木者 于 2007-9-22 14:22 编辑 ]

伐木者

[quote]原帖由 流浪的流氓 于 2007-9-21 10:54 发表

for(i=0; i<4; i++)
             {
                     results = console.nextFloat();    is this working?? assign a Float value to an array ??
              }


I think he meant :
for (int i = 0; i < result.length; i++) {
  results［i］= console.nextFloat();
}

[ 本帖最后由 伐木者 于 2007-9-22 14:14 编辑 ]

base

已经按照建议修改了大部分的内容。。。

请问修改哪个部分才可以使成绩显示为正确的呢？--------------------Configuration: <Default>--------------------
Please enter the student ID number.
20610327
Please enter unit code.1011
Please enter the 4 times results.
40
50
60
70
[F@1270b73Unit Code: 1011
============================
-------  DISPLAY  ----------
Id number: 20610327
Student first name: Sven
Student surname: Liao
Results: [F@1270b73
Grade: 0
============================


Process completed.



Student Class:

/**
* @(#)student.java
*
* student application
*
* @author
* @version 1.00 2007/9/21
*/
import java.util.*;
public class Student
{
        Scanner console = new Scanner(System.in);
       
                                          
        public int idnumber;
        public String firstname;
        public String surname;
        public String unitcode;
    public float [] results = new float[4];
        public int grade;
       
        public Student(String firstname, String surname)
        {
                this.firstname = firstname;
                this.surname = surname;

        }
       
        public void display()
        {
                System.out.println("============================");
                System.out.println("-------  DISPLAY  ----------");
                System.out.println("Id number: " + idnumber);
                System.out.println("Student first name: " + firstname);
                System.out.println("Student surname: " + surname);
                System.out.println("Results: " + results);
                System.out.println("Grade: " + grade);
                System.out.println("============================");
                System.out.println("");
               
       


        }       
        // Mutator Methods, instance variables will be change after this methods.
        public float[] studentresult()
        {
                int i;
                System.out.println("Please enter the 4 times results.");
                for(i=0; i<4; i++)
                {
                        results = console.nextFloat();
                }
                return results;
        }
       
    // Accessor Methods       
        public float[] getresults()
        {
                return results;
        }
   
    // Mutator Methods, this method is used to setting id number.
        public int setidnumber()
        {
                System.out.print("Please enter student ID number.");
                idnumber=console.nextInt();
                return idnumber;
        }
       
        // Mutator Method
        public String setfirstname()
        {
               
        System.out.print("Please enter first Name.");
        firstname = console.next();
                return firstname;
        }
       
        // Mutator Methods.
        public String setsurname()
        {
                System.out.print("Please enter surname.");
                surname = console.next();
                return surname;
        }
       
        // Mutator Methods
        public String setunitcode()
        {
        System.out.print("Please enter unit code.");
        unitcode = console.next();
        return unitcode;
      
        }
       
        // Accessor Methods       
        public String getunitcode()
        {
                System.out.println("Unit Code: " + unitcode);
                return unitcode;
        }

        // Accessor Methods       
        public int idnumber()
        {
                System.out.println("Please enter the student ID number.");
                idnumber= console.nextInt();
                return idnumber;
        }
       
       
        // Accessor Methods       
        public int getgrade()
        {
           if (grade>80)
                   System.out.println("HD");
                     else if (grade>70)
                             System.out.println("D");
                             else if (grade>60)
                                     System.out.println("C");
                                     else if (grade>50)
                                             System.out.println("P");
                                             else if (grade>0)
                                                     System.out.println("N");
                                                    
                   return grade;
                  
        }
}
   



Driver Class


public class Driver
{
   
    public static void main(String[] args)
    {
           
     Student svenL = new Student("Sven", "Liao");
            svenL.firstname = "Sven";
         svenL.surname = "Liao";       
         svenL.idnumber();
         svenL.setunitcode();
         
         svenL.studentresult();
            System.out.print(svenL.getresults());
            
     svenL.getresults();
         svenL.getunitcode();
         svenL.getgrade();
            svenL.display();       
           

    }
}

[ 本帖最后由 base 于 2007-9-22 20:58 编辑 ]

伐木者

Did you get the last sentence on level 5?

base

In Student Class:

public Student(String firstname, String surname, float results)
        {
                this.firstname = firstname;
                this.surname = surname;
                this.results = results;

        }

In Driver
Student svenL = new Student("Sven", "Liao");
            svenL.firstname = "Sven";
         svenL.surname = "Liao";
         svenL.results(50, 60, 70, 80);         

--------------------Configuration: <Default>--------------------
C:\Documents and Settings\Sven\桌面\1002 Week10 Test\20610327\Driver.java:9: 找不到符号
符号： 构造函数 Student(java.lang.String,java.lang.String)
位置： 类 Student
     Student svenL = new Student("Sven", "Liao");
                     ^
C:\Documents and Settings\Sven\桌面\1002 Week10 Test\20610327\Driver.java:12: 找不到符号
符号： 方法 results(int,int,int,int)
位置： 类 Student
     svenL.results(50, 60, 70, 80);  
          ^
C:\Documents and Settings\Sven\桌面\1002 Week10 Test\20610327\Student.java:26: 不兼容的类型
找到： float
需要： float[]
        this.results = results;
                       ^
3 错误

Process completed.

[ 本帖最后由 base 于 2007-9-22 22:11 编辑 ]

伐木者

To print out the contents of an array, you have to loop through it, or use Arrays.toString()