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I'm new to java, I'm trying to select shape using jframe and then display the area using console output, I tried using it as follow, but it's giving me an error. Not sure how to do an if statement, it says non static variable can't be referenced from static context. How to fix my code? Thank you in advance

public class design extends javax.swing.JFrame {

    int type;
    int xtl, ytl, xtr, ytr, xbl, ybl,xbr, ybr;
    /**
     * Creates new form design
     */
    public design() {
        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">                          
    private void initComponents() {

        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();
        jButton3 = new javax.swing.JButton();
        jButton4 = new javax.swing.JButton();
        jButton5 = new javax.swing.JButton();
        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jLabel3 = new javax.swing.JLabel();
        jLabel4 = new javax.swing.JLabel();
        jLabel5 = new javax.swing.JLabel();
        jLabel6 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jTextField2 = new javax.swing.JTextField();
        jTextField3 = new javax.swing.JTextField();
        jTextField4 = new javax.swing.JTextField();
        jTextField5 = new javax.swing.JTextField();
        jTextField6 = new javax.swing.JTextField();
        jTextField7 = new javax.swing.JTextField();
        jTextField8 = new javax.swing.JTextField();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton1.setText("Quadrilateral");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jButton2.setText("Rectangle");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });

        jButton3.setText("Parallelogram");
        jButton3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton3ActionPerformed(evt);
            }
        });

        jButton4.setText("Square");
        jButton4.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton4ActionPerformed(evt);
            }
        });

        jButton5.setText("Trapezoid");
        jButton5.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton5ActionPerformed(evt);
            }
        });

        jLabel1.setText("X:");

        jLabel2.setText("Y:");

        jLabel3.setText("Top left point");

        jLabel4.setText("Top right point");

        jLabel5.setText("Bottom left point");

        jLabel6.setText("Bottom right point");

        jTextField1.setText("               ");
        jTextField1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField1ActionPerformed(evt);
            }
        });

        jTextField2.setText("               ");
        jTextField2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField2ActionPerformed(evt);
            }
        });

        jTextField3.setText("               ");
        jTextField3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField3ActionPerformed(evt);
            }
        });

        jTextField4.setText("               ");
        jTextField4.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField4ActionPerformed(evt);
            }
        });

        jTextField5.setText("              ");
        jTextField5.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField5ActionPerformed(evt);
            }
        });

        jTextField6.setText("               ");
        jTextField6.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField6ActionPerformed(evt);
            }
        });

        jTextField7.setText("               ");
        jTextField7.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField7ActionPerformed(evt);
            }
        });

        jTextField8.setText("               ");
        jTextField8.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField8ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(24, 24, 24)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(47, 47, 47)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                .addGap(90, 90, 90)
                                .addComponent(jButton4)
                                .addGap(142, 142, 142)
                                .addComponent(jButton5)
                                .addGap(0, 0, Short.MAX_VALUE))
                            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                                .addGap(0, 40, Short.MAX_VALUE)
                                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                                        .addComponent(jTextField1)
                                        .addComponent(jTextField5))
                                    .addComponent(jLabel3))
                                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                    .addGroup(layout.createSequentialGroup()
                                        .addGap(39, 39, 39)
                                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                            .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                                            .addComponent(jTextField6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                                        .addGap(58, 58, 58)
                                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                            .addComponent(jTextField7, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                                            .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                                        .addGap(67, 67, 67)
                                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                                            .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                                            .addComponent(jTextField8, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                                    .addGroup(layout.createSequentialGroup()
                                        .addGap(44, 44, 44)
                                        .addComponent(jLabel4)
                                        .addGap(27, 27, 27)
                                        .addComponent(jLabel5)
                                        .addGap(32, 32, 32)
                                        .addComponent(jLabel6)))
                                .addGap(137, 137, 137))))
                    .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel2)
                            .addComponent(jLabel1))
                        .addContainerGap())
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jButton1)
                        .addGap(148, 148, 148)
                        .addComponent(jButton3)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addComponent(jButton2)
                        .addGap(75, 75, 75))))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(20, 20, 20)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1)
                    .addComponent(jButton3)
                    .addComponent(jButton2))
                .addGap(26, 26, 26)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton4)
                    .addComponent(jButton5))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 73, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel3)
                    .addComponent(jLabel4)
                    .addComponent(jLabel5)
                    .addComponent(jLabel6))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jTextField8, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jTextField7, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jLabel2)
                    .addComponent(jTextField5, javax.swing.GroupLayout.PREFERRED_SIZE, 20, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jTextField6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(43, 43, 43))
        );

        pack();
    }// </editor-fold>                        

    private void jTextField7ActionPerformed(java.awt.event.ActionEvent evt) {                                            
            ybl = Integer.parseInt(jTextField7.getText());    }                                           

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
            type =1;
        // TODO add your handling code here:
    }                                        

    private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                         
            type =2;
// TODO add your handling code here:
    }                                        

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
            type =3;

    }                                        

    private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {                                         
            type =4;
            // TODO add your handling code here:
    }                                        

    private void jButton5ActionPerformed(java.awt.event.ActionEvent evt) {                                         
            type =5;
        // TODO add your handling code here:
    }                                        

    private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                            
            xtl = Integer.parseInt(jTextField1.getText());

    }                                           

    private void jTextField5ActionPerformed(java.awt.event.ActionEvent evt) {                                            
            ytl = Integer.parseInt(jTextField5.getText());

    }                                           

    private void jTextField3ActionPerformed(java.awt.event.ActionEvent evt) {                                            
            xtr = Integer.parseInt(jTextField3.getText());
    }                                           

    private void jTextField6ActionPerformed(java.awt.event.ActionEvent evt) {                                            
            ytr = Integer.parseInt(jTextField6.getText());
    }                                           

    private void jTextField4ActionPerformed(java.awt.event.ActionEvent evt) {                                            
            xbl = Integer.parseInt(jTextField4.getText());
    }                                           

    private void jTextField2ActionPerformed(java.awt.event.ActionEvent evt) {                                            
            xbr = Integer.parseInt(jTextField2.getText());
    }                                           

    private void jTextField8ActionPerformed(java.awt.event.ActionEvent evt) {                                            
            ybr = Integer.parseInt(jTextField8.getText());                                               
    }                                           
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {

        if (type==1){
       System.out.println("Qoordinates of Quadrilateral are");
        }
       if (type==2){
       System.out.println("Text2");
        }


        /* 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(design.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(design.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(design.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(design.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() {
                System.out.println("Hello World");
                new design().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JButton jButton3;
    private javax.swing.JButton jButton4;
    private javax.swing.JButton jButton5;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JLabel jLabel6;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JTextField jTextField2;
    private javax.swing.JTextField jTextField3;
    private javax.swing.JTextField jTextField4;
    private javax.swing.JTextField jTextField5;
    private javax.swing.JTextField jTextField6;
    private javax.swing.JTextField jTextField7;
    private javax.swing.JTextField jTextField8;
    // End of variables declaration                   
}
MadProgrammer
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  • Have a look at [Understanding Class Members](https://docs.oracle.com/javase/tutorial/java/javaOO/classvars.html) and [Variables](https://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html) – MadProgrammer Sep 24 '15 at 00:12

1 Answers1

0

(Style nit: your design class should be named Design.)

In your main method, you hadn't created a new Design object yet. You can only access type for a Design instance.

C. K. Young
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