The JFrame “Window” and its contents don't show up, why?

Question

The data is stored in a file called Jobs.json here is the file:

[
{
  "JobTitle":" Computer Programmer",
  "field":"Software Development",
  "Company":"Ideal Life",
  "Education":"Any undergraduate degree",
  "Salary":"$68,500 - $75,000 a year",
  "Hours":"37.5 hours per week",

  "Experience":"Solid coding chops with HTML, CSS, Javascript; this includes JQuery and Bootstrap",

  "Responsibilities":"Assist in producing data exports/reports via SQL query routines",

  "University":"Bachelor of Engineering:\nEnglish/Anglais (ENG4U/EAE4U preferred)\nAdvanced Functions (MHF4U)\nPhysics (SPH4U)\nChemistry (SCH4U)\nCalculus and Vectors (MCV4U)\nGrades should be 80-87% for consideration.",
  "College":"N/A"
},
{
  "JobTitle":"IT Specialist",
  "field":"IT",
  "Company":"Meriti Wealth Advisors Inc",
  "Education":"a diploma/degree in Computer Science",
  "Salary":"$68,500 - $75,000 a year",
  "Hours":"Not given",
  "Experience":"sample text",
  "Responsibilities":"more sample text",
  "University":"Low 90%s to consider",
  "College":"N/A"
},
{

  "JobTitle":"Computer Programmer",
  "field":"Computer Software",
  "Company":"IBM",
  "Education":"Bachelor’s degree in Computer Science, Software Engineering or equivalent",
  "Salary":"Not given",
  "Hours":"Not given",
  "Experience":"responsive web applications",
  "Responsibilities":"Work alongside our multidisciplinary team of developers and designers",
  "University":"Low 90%s to consider",
  "College":"N/A"
},
{
  "JobTitle":"Computer programmer",
  "field":"Computer Software/Transportation Management",
  "Company":"Degama",
  "Education":"College, or other non-university certificate or diploma from a program of 1 year to 2 years",
  "Salary":"$73,000.00 per year",
  "Hours":"40 hours per week",
  "Experience":"Experience an asset",
  "Responsibilities":"Write, modify, integrate and test software code;",
  "University":"N/A",
  "College":"(Seneca Computer Programming Diploma)\nOntario Secondary School Diploma (OSSD) or equivalent with:\nGrade 12 English: ENG4(C) or ENG4(U)\nGrade 12 Mathematics: (C) or (U) or Grade 11 Mathematics: (U) or (M)"
},
{
  "JobTitle":"Software Test Engineer",
  "field":"Auto industry",
  "Company":"General Motors",
  "Education":"Bachelor's degree in Computer Science, Software Engineering, or equivalent field",
  "Salary":"Not given",
  "Hours":"Not given",
  "Experience":"Advanced degrees preferred",
  "Responsibilities":"Define test strategy and test plan based on software development plan",
  "University":"Low 90%s to consider",
  "College":"N/A"
}
]

This is the java program I wrote, i tried saving everything on the JSON file in the program and putting the job titles into a combo box.

import java.awt.Color;
import java.awt.Font;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.Insets;
import java.awt.Panel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JComboBox;


import org.json.JSONArray;
import org.json.JSONObject;


public class Main 
{
    static Scanner input;
    static String file;
    static String[] jobs;
    static String[] field;
    static String[] company;
    static String[] education;
    static String[] salary;
    static String[] hours;
    static String[] experience;
    static String[] responsibilities;
    static String[] university;
    static String[] college;
    static JComboBox<String> combo = new JComboBox <String>()


public static void main(String[] args) 
{
    try
    {
        input = new Scanner(new File("Jobs.json"));
    }
    catch(FileNotFoundException e)
    {
        System.out.println("error");
    }
    while(input.hasNextLine());
    {
        file+=input.nextLine();
    }
    final JSONArray jason=new JSONArray(file);
    for(int a=0;a<jason.length();a++)
    {
        JSONObject object=jason.getJSONObject(a);
        jobs[a]=object.getString("JobTitle");
        field[a]=object.getString("field");
        company[a]=object.getString("Company");
        education[a]=object.getString("Education");
        salary[a]=object.getString("Salary");
        hours[a]=object.getString("Hours");
        experience[a]=object.getString("Experience");
        responsibilities[a]=object.getString("Responsibilities");
        university[a]=object.getString("University");
        college[a]=object.getString("College");
        combo.addItem(jobs[a]);
    }
    JFrame jframe = new JFrame("Window");
    jframe.setSize(640, 480);
    jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    jframe.setVisible(true);


    JPanel jpanel = new JPanel();
    jpanel.setBackground(Color.CYAN);

    GridBagLayout layout = new GridBagLayout();
    GridBagConstraints constraints = new GridBagConstraints();

    final JLabel label = new JLabel(" ");
    label.setFont(new Font("Ariel", Font.PLAIN, 14));

    JButton button = new JButton("Press for Info");
    button.addActionListener(new ActionListener()
    {
        @Override
        public void actionPerformed(ActionEvent e) 
        {

            label.setText(combo.getSelectedItem().toString());
        }

    });

            //Add to the jpanel
            jpanel.setLayout(layout);
            constraints.anchor = GridBagConstraints.NORTHWEST;
            constraints.gridx = 0;
            constraints.gridy = 0;
            constraints.weightx = 1;
            constraints.fill = GridBagConstraints.HORIZONTAL;
            //insets(top, left, bottom, right);
            constraints.insets = new Insets(0,0,0,200);
            jpanel.add(combo,constraints);

            //Add Button
            constraints.gridx = 0;
            constraints.gridy = 1;
            constraints.weightx = 0.1;
            constraints.fill = GridBagConstraints.NONE;
            //insets(top, left, bottom, right);
            constraints.insets = new Insets(0,0,0,0);
            jpanel.add(button,constraints);

            //Add label
            constraints.gridx = 0;
            constraints.gridy = 2;
            constraints.insets = new Insets(10,0,0,0);
            jpanel.add(label,constraints);

            //Add the panel container to our window
            jframe.add(jpanel);
            jframe.setVisible(true);
}

}

Answer 1

replace

while(input.hasNextLine());

with

while(input.hasNextLine())

in your main method

your now code will run into infinite-loop.