<div>과제중인데.. 막히는부분이있어서 질문드립니다</div> <div><br></div> <div>볼드부분이 질문의 부분인데요</div> <div><br></div> <div>텍스트 필드를 비우고는 연산이안되서 </div> <div>java.lang.NumberFormatException: empty String</div> <div><br></div> <div>이런에러가나오고</div> <div><br></div> <div>저렇게 텍스트 필드를 숫자로지정해놓고하면 다른숫자를 넣어도 저 200000의 숫자로 돌아갑니다</div> <div><br></div> <div>텍스트필드에 원하는 숫자를 넣고 그걸로 연산을 할수있는방법을 알고싶습니다 도와주세요</div> <div>/*</div> <div> * To change this license header, choose License Headers in Project Properties.</div> <div> * To change this template file, choose Tools | Templates</div> <div> * and open the template in the editor.</div> <div> */</div> <div>package Assignment09;</div> <div><br></div> <div>import javax.swing.*;</div> <div>import java.awt.*;</div> <div>import java.awt.event.*;</div> <div><br></div> <div>/**</div> <div> *</div> <div> * @author </div> <div> */</div> <div>public class Assignment09 extends JFrame implements ItemListener{</div> <div><br></div> <div>    JComboBox RnT = new JComboBox();</div> <div>    FlowLayout flow = new FlowLayout();</div> <div>    JLabel Rnt = new JLabel("Rate and Term");</div> <div>    JLabel princi = new JLabel("Principal");</div> <div>    JTextField principal = new JTextField(15);</div> <div>    JTextField monthlyPayment = new JTextField(15);</div> <div>    double[] Rate = {5.35, 5.5,5.75};</div> <div>    double[] Term = {7, 15, 30};</div> <div>    double mp = 0.0;</div> <div>    </div> <div>    double rate, term, pri;</div> <div>   </div> <div>    String output;</div> <div>    </div> <div>    public Assignment09()</div> <div>    {</div> <div>        super("calculate monthly payment");</div> <div>        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);</div> <div>        JPanel pane = new JPanel();</div> <div>        pane.setLayout(flow);</div> <div>        RnT.addItemListener(this);</div> <div>        pane.add(Rnt);</div> <div>        RnT.addItem("7 years, 5.35 % rate");</div> <div>        RnT.addItem("15 years, 5.5% rate");</div> <div>        RnT.addItem("30 years 5.75% rate");</div> <div>        pane.add(RnT);</div> <div>        pane.add(princi);</div> <div>        pane.add(principal);</div> <div>        </div> <div>        pane.add(monthlyPayment);</div> <div>        setContentPane(pane);</div> <div>    }</div> <div>    public static void main(String[] args)</div> <div>    {</div> <div>        JFrame Frame = new Assignment09();</div> <div>        Frame.setSize(500,500);</div> <div>        Frame.setVisible(true);</div> <div>        </div> <div>    }</div> <div>    </div> <div>    public void itemStateChanged(ItemEvent list) {</div> <div>        </div> <div>        int num;</div> <div>        </div> <div><b>        Object source = list.getSource(); </b></div> <div><b>        principal.setText("200000");</b></div> <div><b>        String p = principal.getText();</b></div> <div><b>        double prin = Double.parseDouble(p);</b></div> <div><b>        </b></div> <div>        if( source == RnT)</div> <div>        {</div> <div>          </div> <div>            num = RnT.getSelectedIndex();</div> <div>            </div> <div>            rate = Rate[num] /1200;</div> <div>            term = Term[num] * 12;</div> <div>            pri = prin*rate/(1.0-(Math.pow(rate+1, -term)));</div> <div>            </div> <div>            output = Double.toString(pri);</div> <div>            </div> <div>            monthlyPayment.setText(output);</div> <div>               </div> <div>        }</div> <div>        //throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.</div> <div>    }</div> <div>    </div> <div>}</div> <div><br></div>