Calc

/**
 * /

/**
 * @author mirchevsvilen
 *
 */
import java.text.DecimalFormat;import java.io.*;import javax.swing.JOptionPane;import java.awt.*;import java.awt.event.*;import  javax.swing.*;import javax.swing.event.*;import java.awt.font.*;
public class Calc extends Frame {
  Double x1 = 0d;Double x2 = 0d;Double d = 0d;
  private JButton btnRechne = new JButton("Calculate");
  private JTextField tbxa = new JTextField("a");
  private JTextField tbxb = new JTextField("b");
  private JTextField tbxc = new JTextField("c");
  private JTextField tbxdiscriminant  = new JTextField("D");
  private JTextField tbxx1  = new JTextField("x1");
  private JTextField tbxx2  = new JTextField("x2");
  private JLabel lbla = new JLabel("a:");
  private JLabel lblb = new JLabel("b:");
  private JLabel lblc = new JLabel("c:");
  private JLabel lblkvadratnouravnenie = new JLabel("<html><h1><b>(ax<sup>2</sup>+bx-c = 0)</b></h1></html>");
  private JLabel lblx1 = new JLabel("x1:");
  private JLabel lblx2 = new JLabel("x2:");
  private JLabel lbldiscriminant = new JLabel("D:");
  private JButton btnReset = new JButton("Reset");
  private JFrame frm = new JFrame("");
  private JMenuBar menubar = new JMenuBar();
  private JMenu menu1  = new JMenu("File");
  private Panel cp = new Panel(null);
  private JMenuItem exit = new JMenuItem("Exit") ;
  private Font font = new Font("Verdana", Font.BOLD, 12);
  private ButtonListener  meinBl = new  ButtonListener ();
  //Constructor
  public Calc (){
    super("Calculator");
    menubar.add(menu1);
    menu1.add(exit);
    exit.addActionListener(meinBl);
    frm.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
    setLocationRelativeTo(null);
    frm.add(cp);
    frm.setJMenuBar(menubar);
    frm.setSize(500,500);
    frm.setResizable(false);
    frm.setVisible(true);
    cp.setBackground(Color.WHITE);
    //******Buttons***************
    //***************
    btnReset.setBounds(250,300,100,50);
    btnReset.setFont(font);
    btnReset.setBackground(Color.RED);
    btnReset.setForeground(Color.WHITE);
    btnReset.addActionListener(new ActionListener (){
      public void actionPerformed(ActionEvent evt){
        btnReset_ActionPerformed(evt);
      }});
    cp.add(btnReset);
    btnRechne.setBounds(50, 300, 100, 50);
    btnRechne.setFont(font);
    btnRechne.setBackground(Color.YELLOW);
    btnRechne.addActionListener(new ActionListener (){
      public void actionPerformed(ActionEvent evt){
        btnRechne_ActionPerformed(evt);
      } } );
    cp.add(btnRechne);
    //******TextBox***************
    //***************
    tbxa.setBounds(20,80,110,30);
    tbxa.setBackground(Color.WHITE);
    cp.add(tbxa);
    tbxb.setBounds(180,80,110,30);
    tbxb.setBackground(Color.WHITE);
    cp.add(tbxb);
    tbxc.setBounds(320,80,110,30);
    tbxc.setBackground(Color.WHITE);
    cp.add(tbxc);
    tbxdiscriminant.setBounds(50,180,100,30);
    tbxdiscriminant.setBackground(Color.WHITE);
    cp.add(tbxdiscriminant);
    tbxx1.setBounds(190,150,200,30);
    cp.add(tbxx1);
    tbxx2.setBounds(190,200,200,30);
    cp.add(tbxx2);
    //****************Label***************
    //***************
    lblkvadratnouravnenie.setBounds(150,2,300,50);
    cp.add(lblkvadratnouravnenie);
    lbla.setBounds(5,80,20,20);
    cp.add(lbla);
    lblb.setBounds(160,80,20,20);
    cp.add(lblb);
    lblc.setBounds(300,80,20,20);
    cp.add(lblc);
    lblx1.setBounds(160,150,100,30);
    cp.add(lblx1);
    lblx2.setBounds(160,200,100,30);
    cp.add(lblx2);
    lbldiscriminant.setBounds(30,180,100,30);
    cp.add(lbldiscriminant);
    //**********************************************
  }//End of Constructor
  public void  btnRechne_ActionPerformed(ActionEvent evt){
    DecimalFormat df = new DecimalFormat("#.##");
    String textc = this.tbxc.getText();
    Double  zahlc = Double.valueOf((textc));
    String textb = this.tbxb.getText();
    Double  zahlb = Double.valueOf((textb));;
    String texta = this.tbxa.getText();
    Double zahla = Double.valueOf((texta));
    if (zahla != 0) {
      try {
        d = (zahlb*zahlb)-(4*zahla*zahlc);
        textc = d.toString();
        this.tbxdiscriminant.setText(textc);
        if (d > 0) {
          x1 = (-zahlb + Math.sqrt(Math.pow(zahlb, 2) - 4*zahla*zahlc)) / (2*zahla);
          textc = x1.toString();
          this.tbxx1.setText(textc);
          x2 = (-zahlb - Math.sqrt(Math.pow(zahlb, 2) - 4*zahla*zahlc)) / (2*zahla);
          textc = x2.toString();
          this.tbxx2.setText(textc);
        } // end of if
        if (d < 0) {
          this.tbxx1.setText("Error");
          this.tbxx2.setText("Error");
        } // end of if
        if (d == 0) {
          x1 = -zahlb/(2*zahla) + Math.round(x1);
          textc = x1.toString();
          this.tbxx1.setText(textc);
          this.tbxx2.setText("");
        } // end of if
      }
      catch (NumberFormatException e) {
      }
      // end of try
    } else if (zahla == 0) {
      try {
        this.tbxx1.setText("Error");
        this.tbxx2.setText("Error");
      }
      catch (NumberFormatException e) {
        System.out.println("Error");
      }
      // end of try
    } // end of if-else
  }
  public void    btnReset_ActionPerformed(ActionEvent evt){
    this.tbxa.setText("");
    this.tbxb.setText("");
    this.tbxc.setText("");
    this.tbxx1.setText("");
    this.tbxx2.setText("");
    this.tbxdiscriminant.setText("");
  }
  public class ButtonListener implements ActionListener {
    public void actionPerformed(ActionEvent ae) {
      if (ae.getSource() == exit) {
        System.exit(0);
      } // end of if
    }
    }
  public static void main(String[] args) {
    new Calc();
    }//End of main
} //End of Class