import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;

public class SwingFC implements ActionListener {

  JTextField jtfFirst;  // holds the first file name
  JTextField jtfSecond; // holds the second file name

  JButton jbtnComp; // button to compare the files

  JLabel jlabFirst, jlabSecond; // displays prompts
  JLabel jlabResult; // displays results and error messages

  SwingFC() {

    // Create a new JFrame container.
    JFrame jfrm = new JFrame("Compare Files");

    // Specify FlowLayout for the layout manager.
    jfrm.setLayout(new FlowLayout());

    // Give the frame an initial size.
    jfrm.setSize(200, 190);

    // Terminate the program when the user closes the application.
    jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    // Create the text fields for the file names..
    jtfFirst = new JTextField(14);
    jtfSecond = new JTextField(14);

    // Set the action commands for the text fields.
    jtfFirst.setActionCommand("fileA");
    jtfSecond.setActionCommand("fileB");

    // Create the Compare button.
    JButton jbtnComp = new JButton("Compare");

    // Add action listener for the Compare button.
    jbtnComp.addActionListener(this);

    // Create the labels.
    jlabFirst = new JLabel("First file: ");
    jlabSecond = new JLabel("Second file: ");
    jlabResult = new JLabel("");

    // Add the components to the content pane.
    jfrm.add(jlabFirst);
    jfrm.add(jtfFirst);
    jfrm.add(jlabSecond);
    jfrm.add(jtfSecond);
    jfrm.add(jbtnComp);
    jfrm.add(jlabResult);

    // Display the frame.
    jfrm.setVisible(true);
  }

  // Compare the files when the Compare button is pressed.
  public void actionPerformed(ActionEvent ae) {
    int i=0, j=0;

    // First, confirm that both file names have
    // been entered.
    if(jtfFirst.getText().equals("")) {
      jlabResult.setText("First file name missing.");
      return;
    }
    if(jtfSecond.getText().equals("")) {
      jlabResult.setText("Second file name missing.");
      return;
    }

    // Compare files. Use try-with-resources to manage the files.
    try (FileInputStream f1 = new FileInputStream(jtfFirst.getText());
         FileInputStream f2 = new FileInputStream(jtfSecond.getText()))
    {
      // Check the contents of each file.
      do {
        i = f1.read();
        j = f2.read();
        if(i != j) break;
      } while(i != -1 && j != -1);

      if(i != j)
        jlabResult.setText("Files are not the same.");
      else
        jlabResult.setText("Files compare equal.");
    } catch(IOException exc) {
      jlabResult.setText("File Error");
    }
  }

  public static void main(String args[]) {
    // Create the frame on the event dispatching thread.
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        new SwingFC();
      }
    });
  }
}