Dönüştürme Sorunu

 
  private void btnTCalActionPerformed(java.awt.event.ActionEvent evt) {                                         
          int TempC; 
          int TempF; 
           
          if(evt.getSource() == btnTCal){ 
              
              TempC = (int) (((((Double.parseDouble(txtCelsius.getText())*9.0 / 5.0)) +32))); 
              txtFahren.setText(TempC + " °F"); 
              txtCelsius.requestFocus(); 
              txtCelsius.selectAll(); 
              } 
          if(evt.getSource() == btnTCal){ 
               
              TempF = (int) (((((Double.parseDouble(txtFahren.getText())-32)) *5.0 / 9.0))); 
              txtCelsius.setText(TempF + " °C"); 
              txtFahren.requestFocus(); 
              txtFahren.selectAll(); 
          } 
           
      } 
  

private void TempCActionPerformed(java.awt.event.ActionEvent evt) {                                       
          //F° = (9/5) x C° + 32 
          varF = (Double.parseDouble(txtDisplay1.getText())* 9.0 / 5.0+32); 
          txtDisplay2.setText(Double.toString(varF)); 
      }                                      
   
      private void TempFActionPerformed(java.awt.event.ActionEvent evt) {                                       
          //Celsius C = (F-32)/1,8 
          varC = ((Double.parseDouble(txtDisplay1.getText())-32) / 1.8); 
          txtDisplay2.setText(Double.toString(varC)); 
      } 

     
  private void txtCKeyTyped(java.awt.event.KeyEvent evt) {                               
          txtF.setText(""); 
      }                              
   
      private void txtFKeyTyped(java.awt.event.KeyEvent evt) {                               
          txtC.setText(""); 
      }  
  

 
      private void btnTempActionPerformed(java.awt.event.ActionEvent evt) {                                         
          if(!(txtC.getText().equals(""))){ 
              double varF = (Double.parseDouble(txtC.getText())* 9.0 / 5.0+32); 
              txtF.setText(Double.toString(varF)); 
              } 
          else if (!(txtF.getText().equals(""))){ 
              double varC = ((Double.parseDouble(txtF.getText())-32) / 1.8); 
              txtC.setText(Double.toString(varC)); 
          } 
      }  
  

 
      private void txtCMouseReleased(java.awt.event.MouseEvent evt) {                                    
          txtC.setText("");  
      }                                   
   
      private void txtFMouseReleased(java.awt.event.MouseEvent evt) {                                    
          txtF.setText("");  
      }