Java Project – GUI Calculator with Source Code

Program 1

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

package dataflair;

/**
 *
 * @author admin
 */
public class Calculator extends javax.swing.JFrame {

      double num1=0,num2=0;
      double ans=0;
      String operator;
    public Calculator() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">//GEN-BEGIN:initComponents
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        txtoutput = new javax.swing.JTextField();
        btn1 = new javax.swing.JButton();
        btn2 = new javax.swing.JButton();
        btn3 = new javax.swing.JButton();
        btn4 = new javax.swing.JButton();
        btn5 = new javax.swing.JButton();
        btn6 = new javax.swing.JButton();
        btn7 = new javax.swing.JButton();
        btn8 = new javax.swing.JButton();
        btn9 = new javax.swing.JButton();
        btn0 = new javax.swing.JButton();
        btnc = new javax.swing.JButton();
        btndot = new javax.swing.JButton();
        btnplus = new javax.swing.JButton();
        btnminus = new javax.swing.JButton();
        btnmulti = new javax.swing.JButton();
        btndevide = new javax.swing.JButton();
        btnce = new javax.swing.JButton();
        btnequal = new javax.swing.JButton();
        jCheckBox1 = new javax.swing.JCheckBox();
        btnback = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Calculator ");

        txtoutput.setEditable(false);
        txtoutput.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        txtoutput.setHorizontalAlignment(javax.swing.JTextField.RIGHT);

        btn1.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn1.setText("1");
        btn1.setToolTipText("");
        btn1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn1ActionPerformed(evt);
            }
        });

        btn2.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn2.setText("2");
        btn2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn2ActionPerformed(evt);
            }
        });

        btn3.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn3.setText("3");
        btn3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn3ActionPerformed(evt);
            }
        });

        btn4.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn4.setText("4");
        btn4.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn4ActionPerformed(evt);
            }
        });

        btn5.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn5.setText("5");
        btn5.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn5ActionPerformed(evt);
            }
        });

        btn6.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn6.setText("6");
        btn6.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn6ActionPerformed(evt);
            }
        });

        btn7.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn7.setText("7");
        btn7.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn7ActionPerformed(evt);
            }
        });

        btn8.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn8.setText("8");
        btn8.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn8ActionPerformed(evt);
            }
        });

        btn9.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn9.setText("9");
        btn9.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn9ActionPerformed(evt);
            }
        });

        btn0.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btn0.setText("0");
        btn0.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn0ActionPerformed(evt);
            }
        });

        btnc.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btnc.setText("C");
        btnc.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btncActionPerformed(evt);
            }
        });

        btndot.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btndot.setText(".");
        btndot.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btndotActionPerformed(evt);
            }
        });

        btnplus.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btnplus.setText("+");
        btnplus.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnplusActionPerformed(evt);
            }
        });

        btnminus.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btnminus.setText("-");
        btnminus.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnminusActionPerformed(evt);
            }
        });

        btnmulti.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btnmulti.setText("*");
        btnmulti.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnmultiActionPerformed(evt);
            }
        });

        btndevide.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btndevide.setText("/");
        btndevide.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btndevideActionPerformed(evt);
            }
        });

        btnce.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btnce.setText("CE");

        btnequal.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btnequal.setText("=");
        btnequal.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnequalActionPerformed(evt);
            }
        });

        jCheckBox1.setText("On/OFF");
        jCheckBox1.addChangeListener(new javax.swing.event.ChangeListener() {
            public void stateChanged(javax.swing.event.ChangeEvent evt) {
                jCheckBox1StateChanged(evt);
            }
        });

        btnback.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        btnback.setText("<");
        btnback.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnbackActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(txtoutput))
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(75, 75, 75)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                            .addGroup(jPanel1Layout.createSequentialGroup()
                                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                    .addGroup(jPanel1Layout.createSequentialGroup()
                                        .addComponent(btn4, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                        .addComponent(btn5, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                        .addComponent(btn6, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE))
                                    .addGroup(jPanel1Layout.createSequentialGroup()
                                        .addComponent(btn1, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                            .addGroup(jPanel1Layout.createSequentialGroup()
                                                .addComponent(btn0, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                                .addComponent(btndot, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE))
                                            .addGroup(jPanel1Layout.createSequentialGroup()
                                                .addComponent(btn2, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                                .addComponent(btn3, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)))))
                                .addGap(22, 22, 22))
                            .addGroup(jPanel1Layout.createSequentialGroup()
                                .addComponent(btn7, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(btn8, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(btn9, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addGap(22, 22, 22))
                            .addGroup(jPanel1Layout.createSequentialGroup()
                                .addComponent(btnback)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(btnce)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(btnc, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addGap(19, 19, 19)))
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(jPanel1Layout.createSequentialGroup()
                                .addComponent(btnplus, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addGap(18, 18, 18)
                                .addComponent(btnequal, javax.swing.GroupLayout.PREFERRED_SIZE, 125, javax.swing.GroupLayout.PREFERRED_SIZE))
                            .addComponent(btnminus, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btnmulti, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btndevide, javax.swing.GroupLayout.PREFERRED_SIZE, 60, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(34, 34, 34)
                        .addComponent(jCheckBox1)))
                .addGap(0, 170, Short.MAX_VALUE))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addComponent(txtoutput, javax.swing.GroupLayout.PREFERRED_SIZE, 55, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addComponent(jCheckBox1)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 112, Short.MAX_VALUE)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(btnc, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btnce, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btnback, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(btn7, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btn8, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btn9, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(btn4, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btn5, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btn6, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(btn1, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btn2, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btn3, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGap(4, 4, 4)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(btn0, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btndot, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addComponent(btndevide, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(btnmulti, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(btnminus, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(btnplus, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(btnequal, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addContainerGap())))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

        pack();
    }// </editor-fold>//GEN-END:initComponents

    private void btn1ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn1ActionPerformed
        // TODO add your handling code here:
        txtoutput.setText(txtoutput.getText()+"1");
    }//GEN-LAST:event_btn1ActionPerformed

    private void btn2ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn2ActionPerformed
        // TODO add your handling code here:
         txtoutput.setText(txtoutput.getText()+"2");
    }//GEN-LAST:event_btn2ActionPerformed

    private void btn3ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn3ActionPerformed
        // TODO add your handling code here:
        txtoutput.setText(txtoutput.getText()+"3");
    }//GEN-LAST:event_btn3ActionPerformed

    private void btn4ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn4ActionPerformed
        // TODO add your handling code here:
        txtoutput.setText(txtoutput.getText()+"4");
    }//GEN-LAST:event_btn4ActionPerformed

    private void btn5ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn5ActionPerformed
        // TODO add your handling code here:
        txtoutput.setText(txtoutput.getText()+"5");
    }//GEN-LAST:event_btn5ActionPerformed

    private void btn6ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn6ActionPerformed
        // TODO add your handling code here:
        txtoutput.setText(txtoutput.getText()+"6");
    }//GEN-LAST:event_btn6ActionPerformed

    private void btn7ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn7ActionPerformed
        // TODO add your handling code here:
        txtoutput.setText(txtoutput.getText()+"7");
    }//GEN-LAST:event_btn7ActionPerformed

    private void btn8ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn8ActionPerformed
        // TODO add your handling code here:
        txtoutput.setText(txtoutput.getText()+"8");
    }//GEN-LAST:event_btn8ActionPerformed

    private void btn9ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn9ActionPerformed
        // TODO add your handling code here:
        txtoutput.setText(txtoutput.getText()+"9");
    }//GEN-LAST:event_btn9ActionPerformed

    private void btn0ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn0ActionPerformed
        // TODO add your handling code here:
        txtoutput.setText(txtoutput.getText()+"0");
    }//GEN-LAST:event_btn0ActionPerformed

    private void btndotActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btndotActionPerformed
        // TODO add your handling code here:
        txtoutput.setText(txtoutput.getText()+".");
    }//GEN-LAST:event_btndotActionPerformed

    private void btncActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btncActionPerformed
        // TODO add your handling code here:
            txtoutput.setText("");
    }//GEN-LAST:event_btncActionPerformed

    private void btnplusActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnplusActionPerformed
        // TODO add your handling code here:
         //txtoutput.setText(txtoutput.getText()+"+");
            num1=Double.parseDouble(txtoutput.getText());
            txtoutput.setText("");
            operator="+";
    }//GEN-LAST:event_btnplusActionPerformed

    private void btnminusActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnminusActionPerformed
        // TODO add your handling code here:
         //txtoutput.setText(txtoutput.getText()+"-");
        num1=Double.parseDouble(txtoutput.getText());
            txtoutput.setText("");
            operator="-";
    }//GEN-LAST:event_btnminusActionPerformed

    private void btnmultiActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnmultiActionPerformed
        // TODO add your handling code here:
         //txtoutput.setText(txtoutput.getText()+"*");
        num1=Double.parseDouble(txtoutput.getText());
            txtoutput.setText("");
            operator="*";
         
    }//GEN-LAST:event_btnmultiActionPerformed

    private void btndevideActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btndevideActionPerformed
        // TODO add your handling code here:
        // txtoutput.setText(txtoutput.getText()+"/");
        num1=Double.parseDouble(txtoutput.getText());
            txtoutput.setText("");
            operator="/";
    }//GEN-LAST:event_btndevideActionPerformed

    private void jCheckBox1StateChanged(javax.swing.event.ChangeEvent evt) {//GEN-FIRST:event_jCheckBox1StateChanged
        // TODO add your handling code here:
        if(jCheckBox1.isSelected())
            disablecalc();
        else
            enablecalc();
    }//GEN-LAST:event_jCheckBox1StateChanged

    private void btnbackActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnbackActionPerformed
        // TODO add your handling code here:
        int txtlength=txtoutput.getText().length();
        int txtnumber=txtoutput.getText().length()-1;
        if(txtlength>0)
        {
            StringBuilder sb=new StringBuilder(txtoutput.getText());
            sb.deleteCharAt(txtnumber);
            String str;
            str=sb.toString();
            txtoutput.setText(str);
        }
    }//GEN-LAST:event_btnbackActionPerformed

    private void btnequalActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnequalActionPerformed
        // TODO add your handling code here:
        num2=Double.parseDouble(txtoutput.getText());
        switch(operator)
        {
            case "+":
                   ans=num1+num2;break;
            case "-":
                   ans=num1-num2;break;
           case "*":
                   ans=num1*num2;break;
           case "/":
                   ans=num1/num2;break;
   
        }
       txtoutput.setText(Double.toString(ans));
       ans=0;
       operator=null;
    }//GEN-LAST:event_btnequalActionPerformed
    public void disablecalc()
    {
        btn0.setEnabled(false);
        btn1.setEnabled(false);
        btn2.setEnabled(false);
        btn3.setEnabled(false);
        btn4.setEnabled(false);
        btn5.setEnabled(false);
        btn6.setEnabled(false);
        btn7.setEnabled(false);
        btn8.setEnabled(false);
        btn9.setEnabled(false);
        btndot.setEnabled(false);
        btnplus.setEnabled(false);
        btnminus.setEnabled(false);
        btndevide.setEnabled(false);
        btnmulti.setEnabled(false);
         btnequal.setEnabled(false);
         btnc.setEnabled(false);
         btnce.setEnabled(false);
    }
    public void enablecalc()
    {
        btn0.setEnabled(true);
        btn1.setEnabled(true);
        btn2.setEnabled(true);
        btn3.setEnabled(true);
        btn4.setEnabled(true);
        btn5.setEnabled(true);
        btn6.setEnabled(true);
        btn7.setEnabled(true);
        btn8.setEnabled(true);
        btn9.setEnabled(true);
        btndot.setEnabled(true);
        btnplus.setEnabled(true);
        btnminus.setEnabled(true);
        btndevide.setEnabled(true);
        btnmulti.setEnabled(true);
        btnequal.setEnabled(true);
        btnc.setEnabled(true);
        btnce.setEnabled(true);
    }
    
    
    
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(Calculator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Calculator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Calculator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Calculator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Calculator().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify//GEN-BEGIN:variables
    private javax.swing.JButton btn0;
    private javax.swing.JButton btn1;
    private javax.swing.JButton btn2;
    private javax.swing.JButton btn3;
    private javax.swing.JButton btn4;
    private javax.swing.JButton btn5;
    private javax.swing.JButton btn6;
    private javax.swing.JButton btn7;
    private javax.swing.JButton btn8;
    private javax.swing.JButton btn9;
    private javax.swing.JButton btnback;
    private javax.swing.JButton btnc;
    private javax.swing.JButton btnce;
    private javax.swing.JButton btndevide;
    private javax.swing.JButton btndot;
    private javax.swing.JButton btnequal;
    private javax.swing.JButton btnminus;
    private javax.swing.JButton btnmulti;
    private javax.swing.JButton btnplus;
    private javax.swing.JCheckBox jCheckBox1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JTextField txtoutput;
    // End of variables declaration//GEN-END:variables
}