Printing out all the objects in array list

Question

I need to be able to print out the Student objects all variables  in my array list  Is this possible  When i try to print it outputs this sort of thing e g student Student 82701e  I think it s hexadecimal or something  This is my code   package student   public class Student        private String studentName      private String studentNo      private String email      private int year        public Student             this studentName   null          this studentNo   null          this email   null          this year   -1             public Student String nName  String nNum  String nEmail  int nYr            this studentName   nName          this studentNo   nNum          this email   nEmail          this year   nYr             public void setStudentName String newStudentName            this studentName   newStudentName             public void setStudentNo String newStudentNo            this studentNo   newStudentNo             public void setEmail String newEmail            this email   newEmail             public void setYear int newYear            this year   newYear             public String getStudentName             return studentName             public String getStudentNo             return studentNo             public String getEmail             return email             public int getYear             return year           package student   import java util ArrayList  import java util List  import java util Scanner   public class studentTest        public static void main String   args            Scanner input   new Scanner System in              List lt Student gt  Students   new ArrayList              Student student1   new Student             student1 setStudentName  Bob Marley            student1 setStudentNo  N0002            student1 setEmail  student2 student com            student1 setYear 2            Students add student1            Student student2   new Student             student2 setStudentName  Bill Harvey            student2 setStudentNo  N0003            student2 setEmail  student3 student com            student2 setYear 2            Students add student2            Student student3   new Student             student3 setStudentName  John Beans            student3 setStudentNo  N0004            student3 setEmail  student4 student com            student3 setYear 2            Students add student3             System out println  Add new students              System out println  Enter number of students to add              int countStudents   input nextInt             for  int i   0  i  lt  countStudents  i                  Student newStudents   new Student                  System out println  Enter details for student       i   1                 System out println  Enter name                  newStudents setStudentName input next                  System out println  Enter Number                  newStudents setStudentNo input next    System out println  Search by student number                     System out println  Enter email                  newStudents setEmail input next                  System out println  Enter year                  newStudents setYear input nextInt                 Students add newStudents

User · Answer

Whenever you print any instance of your class, the default toString implementation of Object class is called, which returns the representation that you are getting. It contains two parts: - Type and Hashcode

So, in student.Student@82701e that you get as output ->

student.Student is the Type, and
82701e is the HashCode

So, you need to override a toString method in your Student class to get required String representation: -

@Override
public String toString() {
    return "Student No: " + this.getStudentNo() + 
           ", Student Name: " + this.getStudentName();
}

So, when from your main class, you print your ArrayList, it will invoke the toString method for each instance, that you overrided rather than the one in Object class: -

List<Student> students = new ArrayList();

// You can directly print your ArrayList
System.out.println(students); 

// Or, iterate through it to print each instance
for(Student student: students) {
    System.out.println(student);  // Will invoke overrided `toString()` method
}

In both the above cases, the toString method overrided in Student class will be invoked and appropriate representation of each instance will be printed.

User · Answer

You have to define public String toString   method in your Student class  For example   public String toString       return  Student      studentName          studentNo

User · Answer

Override toString   method in Student class as below       Override    public String toString             return   StudentName   this getStudentName                          Student No     this getStudentNo                           Email     this getEmail                           Year       this getYear

[java] Printing out all the objects in array list

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