JComboBox displaying variable two times, why?

**ecliptical** · 01-24-2010, 08:29 AM

Hi guys,
So I was able to set up JComboBox perfectly for my first class, but for my second class when a teacher is added to the class the ComboBox displays the teacher twice.. why? I looked over my code yet I couldn't find any error with it.

All help is appreciated,
Thanks in advance.

-Ecliptical

Here's the code needed to run the program

Java Code:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.util.*;


public class BHSSDatabaseTestDriver
{
   public static void main (String[] args)
  {
  //Create and set up the window.
  JFrame frame = new JFrame("The BHSS Database");
  frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
  BHSSDatabasePanelTABBEDTest tabbedPanel = new BHSSDatabasePanelTABBEDTest();
  //Add content to the window.
  
  //Display the window.
    frame.getContentPane().add(tabbedPanel.primary);
    frame.pack();
    frame.setVisible(true); 
  
}
}

Java Code:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.util.*;

public class BHSSDatabasePanelTABBEDTest extends JPanel implements ActionListener
{
  private JLabel mainDisplay, line1, studNameLabel, osisLabel, cutsLabel, examGradeLabel1, examGradeLabel2, examGradeLabel3, examGradeLabel4, finalExamLabel, homeworkLabel, homeworkCLabel, studentListLabel, teacherNameLabel, teacherListLabel, classNameLabel,
    classListLabel, finalGrade, studentOsisLabel, studentAddressLabel, teacherClassLabel, teacherAddressLabel, yearsServiceLabel, teacherDeptLabel, teacherSalaryLabel;
  private JTabbedPane tabbedPanel;
  private JPanel panel1, panel2, panel3, panel4;
  public static JPanel primary;
  // private JComponent panel1, panel2, panel3, panel4; 
  private JTextField studentNameInput, studentAddressInput, osisInput, cutsInput, homeworkInput, homeworkCInput, examGrade1Input, examGrade2Input, examGrade3Input, examGrade4Input, finalExamInput, 
    projectGrade1Input, projectGrade2Input, projectGrade3Input, yearsServiceInput, teacherAddressInput, teacherNameInput, classNameInput, teacherClassInput, teacherSalaryInput, teacherDeptInput;
  private JComboBox studentNameList, studentNameList2, teacherNameList, classNameList;
  private JButton button1, button2, button3, button4, button5, button6, button7;
  private ArrayList <Teacher> teachers;
  private Teacher [] teachers1;
  
  public BHSSDatabasePanelTABBEDTest()
  {
    teachers = new ArrayList<Teacher>();
    teachers1 = new Teacher[1];
    
    panel2 = new JPanel();
    teacherNameLabel = new JLabel("Name of the Teacher to Add");
    teacherNameInput = new JTextField(20);
    teacherAddressLabel = new JLabel("Teacher's Address: ");
    teacherAddressInput = new JTextField(20);
    teacherClassLabel = new JLabel("Enter the class which this teacher teaches.");
    teacherClassInput = new JTextField(8);
    teacherDeptLabel = new JLabel("Which Department?");
    teacherDeptInput = new JTextField(9);
    teacherSalaryLabel = new JLabel("How much does this teacher make?");
    teacherSalaryInput = new JTextField(6);
    yearsServiceLabel = new JLabel("How many years in service?");
    yearsServiceInput = new JTextField(2);
    button3 = new JButton("Hire this teacher!");
    button3.addActionListener(this);
    teacherListLabel = new JLabel("Select the teacher which you wish to remove.");
    teacherNameList = new JComboBox(teachers1);
    button4 = new JButton("Fire This Teacher!");
    button4.addActionListener(this);
    
    panel2.add(teacherNameLabel);
    panel2.add(teacherNameInput);
    panel2.add(teacherAddressLabel);
    panel2.add(teacherAddressInput);
    panel2.add(teacherClassLabel);
    panel2.add(teacherClassInput);
    panel2.add(teacherDeptLabel);
    panel2.add(teacherDeptInput);
    panel2.add(teacherSalaryLabel);
    panel2.add(teacherSalaryInput);
    panel2.add(yearsServiceLabel);
    panel2.add(yearsServiceInput);
    panel2.add(button3);
    button3.addActionListener(this);
    panel2.add(teacherListLabel);
    panel2.add(teacherNameList);
    panel2.add(button4);
    button4.addActionListener(this);
    
    tabbedPanel = new JTabbedPane();
    add(tabbedPanel);
    tabbedPanel.addTab("Add/Remove Teacher", panel2);
    
    primary = new JPanel();
    primary.setBackground (Color.white);
    primary.setPreferredSize (new Dimension(500, 475));
    primary.setLayout( new BorderLayout() );
    primary.add( tabbedPanel, BorderLayout.CENTER );
    
    tabbedPanel.setTabLayoutPolicy(JTabbedPane.SCROLL_TAB_LAYOUT);
    setPreferredSize(new Dimension(345, 550));
  }
  
  public void actionPerformed(ActionEvent e)
  {
    if(e.getSource() == button3)
    {
      String nameT, addressT, deptT, classT;
      int years;
      double salaryT;
      Teacher teacher = new Teacher();
      nameT = teacherNameInput.getText();
      addressT = teacherAddressInput.getText();
      deptT = teacherDeptInput.getText();
      classT = teacherClassInput.getText();
      years = Integer.parseInt(yearsServiceInput.getText());
      salaryT = Double.parseDouble(teacherSalaryInput.getText());
      teacher.setName(nameT);
      teacher.setAddress(addressT);
      teacher.setDepartment(deptT);
      teacher.setClassTaught(classT);
      teacher.setYearsInService(years);
      teacher.setSalary(salaryT);
      teacherNameList.addItem(teacher.getName());
      teachers.add(teacher);
    }
  } 
}

Java Code:

public class Teacher
{
  private String teacherName, address, department, classTaught;
  private int yearsInService;
  private double salary;
  public Teacher()
  {
    teacherName = "";
    address = "";
    yearsInService = 0;
    salary = 0;
    department = "";
    classTaught = "";
  }
  
  public void setName(String teacherName1)
  {
    teacherName = teacherName1;
  }
  
  public String getName()
  {
    return teacherName;
  }
  
  public void setAddress(String address1)
  {
    address = address1;
  }
  
  public String getAddress()
  {
    return address;
  }
  
  public void setYearsInService(int yearsInService1)
  {
    yearsInService = yearsInService1;
  }
  
  public int getYearsInService()
  {
    return yearsInService;
  }
  
  public void setSalary(double salary1)
  {
    salary = salary1;
  }
  
  public double getSalary()
  {
    return salary;
  }
  
  public void setDepartment(String department1)
  {
    department = department1;
  }
  
  public String getDepartment()
  {
    return department;
  }
  
  public void setClassTaught(String classTaught1)
  {
    classTaught = classTaught1;
  }
  
  public String getClassTaught()
  {
    return classTaught;
  }
  

  
}

**pbrockway2** · 01-24-2010, 09:41 AM

How many times does the actionPerformed() method get called when you click on button3? (addTeacherBut would be a nicer name). You can tell by adding a System.out.println("Ding!") to the start of the if block.

Then ask yourself why it might be being called that number of times.

**ecliptical** · 01-24-2010, 10:07 AM

I did as you said, and indeed it does call it twice.
I have no slight idea as to why though, but I'd guess it has something to do with the loop.

Thanks for the tip pbrockway.

**Fubarable** · 01-24-2010, 02:12 PM

It has nothing to do with a loop. Search through your file and find every reference to button3, and see what you are doing with the button at that time.