Create an application that uses a graphic interface to capture employee data and

Question

Create an application that uses a graphic interface to capture employee data and writes that data to a random access output file. The data required for each employee includes an employee ID number from 1 through 99 inclusive, the first and last names of the employee, and the employee's hourly pay rate. Allow the user to enter data one record at a time and to click a button to save each record. Save the class as CreateRandomEmployeeFile.java. b. Create an application that allows the user to enter an employee ID number. When the user clicks a button, display all the stored data for the employee. Save the file as ReadRandomEmployeeFile.java.

Explanation / Answer

CreateRandomEmployeeFile.java

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class CreateRandomEmployeeFile extends JFrame
implements ActionListener
{
   private JLabel title =
     new JLabel("Employee data");
   Font bigFont = new Font("Helvetica", Font.ITALIC, 24);
   private JLabel prompt =
      new JLabel("    Enter employee data    ");
   private JTextField idField = new JTextField(4);
   private JTextField firstField = new JTextField(14);
   private JTextField lastField = new JTextField(14);
   private JTextField payField = new JTextField(8);
   private JLabel idLabel = new JLabel("ID");
   private JLabel fnLabel = new JLabel("First name");
   private JLabel lnLabel = new JLabel("Last name");
   private JLabel payLabel = new JLabel("Pay rate");
   private JButton enterDataButton =
      new JButton("Enter data");
   private Container con = getContentPane();
   DataOutputStream ostream;
   RandomAccessFile empFile;
   final int RECORD_SIZE = 32;
   final int NUM_RECORDS = 100;
   StringBuffer blankName = new StringBuffer(10);
   public CreateRandomEmployeeFile()
   {
     super("Create File");
     try
     {
        empFile =
          new RandomAccessFile("Employees.dat","rw");
        for(int x = 0; x < NUM_RECORDS; ++x)
        {
           empFile.writeInt(0);
           empFile.writeUTF(blankName.toString());
           empFile.writeUTF(blankName.toString());
           empFile.writeDouble(0.0);
        }
      }
      catch(IOException e)
      {
         System.err.println("File not opened");
         System.exit(1);
      }
      setSize(289, 200);
      con.setLayout(new FlowLayout());
      title.setFont(bigFont);
      con.add(title);
      con.add(prompt);
      con.add(idLabel);
      con.add(idField);
      con.add(fnLabel);
      con.add(firstField);
      con.add(lnLabel);
      con.add(lastField);
      con.add(payLabel);
      con.add(payField);
      con.add(enterDataButton);
      enterDataButton.addActionListener(this);
      setVisible(true);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   }
   @Override
   public void actionPerformed(ActionEvent e1)
   {
     final int MAXNUM = 99;
     int num;
     double pay;
     try
     {
         num = Integer.parseInt(idField.getText());
         pay = Double.parseDouble(payField.getText());
         if(num > MAXNUM)
            num = MAXNUM;
         empFile.seek((num - 1) * RECORD_SIZE);
         empFile.writeInt(num);
         empFile.writeUTF(firstField.getText());
         empFile.writeUTF(lastField.getText());
         empFile.writeDouble(pay);
         idField.setText("");
         lastField.setText("");
         firstField.setText("");
         payField.setText("");
      }
      catch(NumberFormatException e2)
      {
         System.err.println("Invalid employee ID number");
      }
      catch(IOException e3)
      {
          System.err.println("Error writing file");
          System.exit(1);
      }
   }
   public static void main(String[] args)
   {
      CreateRandomEmployeeFile file = new CreateRandomEmployeeFile();
   }
}

ReadRandomEmployeeFile.java

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ReadRandomEmployeeFile extends JFrame
implements ActionListener
{
   private JLabel title =
     new JLabel("Employee data");
   Font bigFont = new Font("Helvetica", Font.ITALIC, 24);
   private JLabel prompt =
      new JLabel("    Enter empployee data    ");
   private JTextField idField = new JTextField(4);
   private JTextField firstField = new JTextField(14);
   private JTextField lastField = new JTextField(14);
   private JTextField payField = new JTextField(8);
   private JLabel idLabel = new JLabel("ID");
   private JLabel fnLabel = new JLabel("First name");
   private JLabel lnLabel = new JLabel("Last name");
   private JLabel payLabel = new JLabel("Pay rate");
   private JButton enterDataButton =
      new JButton("Enter data");
   private Container con = getContentPane();
   DataOutputStream ostream;
   RandomAccessFile empFile;
   final int RECORD_SIZE = 32;
   final int NUM_RECORDS = 100;
   StringBuffer blankName = new StringBuffer(10);
   public ReadRandomEmployeeFile()
   {
     try
     {
       empFile =
          new RandomAccessFile("Employees.dat","rw");
     }
     catch(IOException e)
     {
        System.err.println("File not opened");
        System.exit(1);
     }
     setSize(280, 200);
     con.setLayout(new FlowLayout());
     title.setFont(bigFont);
     con.add(title);
     con.add(idLabel);
     con.add(idField);
     con.add(enterDataButton);
     enterDataButton.addActionListener(this);
     con.add(fnLabel);
     con.add(firstField);
     con.add(lnLabel);
     con.add(lastField);
     con.add(payLabel);
     con.add(payField);
     setVisible(true);
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   }
   @Override
   public void actionPerformed(ActionEvent e1)
   {
      String firstName;
      String lastName;
      int num;
      double pay;
      try
      {
         num = Integer.parseInt(idField.getText());
         empFile.seek((num - 1) * RECORD_SIZE);
         num = empFile.readInt();
         firstName = empFile.readUTF();
         lastName = empFile.readUTF();      
         pay = empFile.readDouble();
         idField.setText("" + num);
         firstField.setText(firstName);
         lastField.setText(lastName);
         payField.setText("" + pay);
      }
      catch(NumberFormatException e2)
      {
         System.err.println("Invalid employee number");
      }
      catch(IOException e3)
      {
          System.err.println("Error reading file");
          System.exit(1);
      }
   }
   public static void main(String[] args)
   {
      ReadRandomEmployeeFile file = new ReadRandomEmployeeFile();
   }
}

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