kalkulator sederhana

operasiMatematika.java

   private void btnTambahActionPerformed(java.awt.event.ActionEvent evt) {                                          
        // TODO add your handling code here:
        operation = 0;
        lblOperasi.setText("+");
        hasChooseAnOperation =true;  
    }                                         

    private void btnKurangActionPerformed(java.awt.event.ActionEvent evt) {                                          
        // TODO add your handling code here:
        operation = 1;
        lblOperasi.setText("-");
        hasChooseAnOperation =true;
    }                                         

    private void btnKaliActionPerformed(java.awt.event.ActionEvent evt) {                                        
        // TODO add your handling code here:
        operation = 2;
        lblOperasi.setText("*");
        hasChooseAnOperation =true;
    }                                       

    private void btnBagiActionPerformed(java.awt.event.ActionEvent evt) {                                        
        // TODO add your handling code here:
        operation = 3;
        lblOperasi.setText("/");
        hasChooseAnOperation =tr
    }