Java：通过JOptionPane对话框将数据存储在对象数组中

Question

I need to know how I can insert data inside objects inside an array of objects using my already made Set methods.

i need to know how should i do it through user , i mean JOptionPane input dialog

student[] s = new student[5];

for (int i=1 ; i <= s.length ;i++) {
    s[i] = new student(i,"AAA","Ecommerce",0.0);
}

for (int i=1; i<=s.length;i++) {
    name = JOptionPane.showInputDialog("Please Write Name for student n " + i);
    major = JOptionPane.showInputDialog("Please Write Major for student n " + i);
    gpa = Double.parseDouble(JOptionPane.showInputDialog("Please Write GPA for student n " +i));

    s[i] = new student(i,name,major,gpa);  
}

I tried to do vars here that get data from user by JOptionPane, but it seems that i only use my already made constructor , not the Set methods.

I need to use the methods because it has some validation code inside it.

Any ideas?

Answer 1

Don't use values as constructor parameters.

Use only implicit constructor that will allocate memory. As for set methods, write them like :

public void setName(String name) { this.name = name; }

In this set methods do your validation code . Your class needs to have private attiributes, which are exact same as your constructor parameters.

Then change line s[i]=new student(i,name,major,gpa); with

s[i] = new Student();
s[i].setNumber(i);
s[i].setName(name);
s[i].setMajor(major);
s[i].setGpa(gpa);

I hope this is what you meant

Edit : Or continue using constructors and do validaing with parameters BEFORE you make new instance of Student

Answer 2

It's not so clear but actually what you want to do is to inizialize a student without adding it to the array until you are sure that fields are correct

Student[] s = new Student[5];
String name, major;
double gpa;
boolean isCorrect = false;
Student currentStudent;

// in your code there is i = 1, is it intended or mistake?
for (int i=0; i <= s.length; i++)
{
  currentStudent = new Student();

  while (!isCorrect)
  {
    name = JOptionPane.showInputDialog("Please Write Name for student n " + i);
    isCorrect = currentStudent.setName(name);

    if (!isCorrect)
      JOptionPane.showMessageDialog(null, "Errors in validating name!");
  }

  isCorrect = false;
  while (!isCorrect)
  {
    major = JOptionPane.showInputDialog("Please Write Major for student n " + i);
    isCorrect = currentStudent.setMajor(major);

    if (!isCorrect)
      JOptionPane.showMessageDialog(null, "Errors in validating major!");
  }

  isCorrect = false
  while (!isCorrect)
  {
    gpa = Double.parseDouble(JOptionPane.showInputDialog("Please Write GPA for student n " +i));
    isCorrect = currentStudent.setGPA(gpa);

    if (!isCorrect)
      JOptionPane.showMessageDialog(null, "Errors in validating GPA!");
  }

  s[i] = currentStudent;
}

This approach will keep asking the user the same field until it's correct.. of course your setters will need to return a boolean that is false if validation failed.