请帮我修改我的代码!
问题很可能出现在 getValues 方法中。
每次我输入 2 个值并单击计算按钮时，都会出现很多错误。
我使用 NetBeans 对其进行了编程，这就是代码看起来不精简的原因。
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* @author cshames
*/
import java.text.DecimalFormat;
import java.lang.Math.*;
public class EnergyForm extends javax.swing.JFrame {
public static DecimalFormat hundred = new DecimalFormat("0.00");
public static double voltageValue;
public static double currentValue;
public static double resistanceValue;
public static double powerValue;
/**
* Creates new form EnergyForm
*/
public EnergyForm() {
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() {
voltageBox = new javax.swing.JTextField();
currentBox = new javax.swing.JTextField();
resistanceBox = new javax.swing.JTextField();
powerBox = new javax.swing.JTextField();
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();
calculateButton = new javax.swing.JButton();
resetButton = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
voltageBox.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
voltageBoxActionPerformed(evt);
}
});
currentBox.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
currentBoxActionPerformed(evt);
}
});
resistanceBox.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
resistanceBoxActionPerformed(evt);
}
});
powerBox.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
powerBoxActionPerformed(evt);
}
});
jLabel1.setText("Voltage:");
jLabel2.setText("Current:");
jLabel3.setText("Resistance:");
jLabel4.setText("Power:");
jLabel5.setFont(new java.awt.Font("Comic Sans MS", 0, 14)); // NOI18N
jLabel5.setText("Ohm's Law Converter");
calculateButton.setText("Calculate");
calculateButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
calculateButtonActionPerformed(evt);
}
});
resetButton.setText("Reset");
resetButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
resetButtonActionPerformed(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()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(66, 66, 66)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel3)
.addComponent(jLabel4))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(powerBox, javax.swing.GroupLayout.DEFAULT_SIZE, 50, Short.MAX_VALUE)
.addComponent(resistanceBox))
.addGap(0, 0, Short.MAX_VALUE))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(71, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addComponent(calculateButton)
.addGap(33, 33, 33)
.addComponent(resetButton))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel1)
.addComponent(jLabel2))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(currentBox, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(voltageBox, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(170, 170, 170)))))
.addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
.addGap(98, 98, 98)
.addComponent(jLabel5, javax.swing.GroupLayout.PREFERRED_SIZE, 151, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(21, 21, 21)
.addComponent(jLabel5)
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(voltageBox, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel1))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(currentBox, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel2))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(resistanceBox, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel3))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(powerBox, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel4))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(resetButton)
.addComponent(calculateButton))
.addContainerGap(30, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void voltageBoxActionPerformed(java.awt.event.ActionEvent evt) {
getValues();
}
private void resistanceBoxActionPerformed(java.awt.event.ActionEvent evt) {
getValues();
}
private void powerBoxActionPerformed(java.awt.event.ActionEvent evt) {
getValues();
}
private void currentBoxActionPerformed(java.awt.event.ActionEvent evt) {
getValues();
}
private void calculateButtonActionPerformed(java.awt.event.ActionEvent evt) {
getValues();
}
private void resetButtonActionPerformed(java.awt.event.ActionEvent evt) {
powerBox.setText(null);
voltageBox.setText(null);
currentBox.setText(null);
resistanceBox.setText(null);
}
/**
* @param args the command line arguments
*/
//help here please!
public static void getValues() {
voltageValue = Float.parseFloat(voltageBox.getText());
resistanceValue = Float.parseFloat(resistanceBox.getText());
currentValue = Float.parseFloat(currentBox.getText());
powerValue = Float.parseFloat(powerBox.getText());
//if(current==true&&voltage==true){//finds resistance & power
if(currentBox.getText() != null && voltageBox.getText() != null) {
resistanceValue=voltageValue/currentValue;
powerValue=voltageValue*currentValue;
String resistanceValueString = hundred.format(resistanceValue);
String powerValueString = hundred.format(powerValue);
resistanceBox.setText(resistanceValueString);
powerBox.setText(powerValueString);
}
else if(currentBox.getText() != null && resistanceBox.getText() != null){//finds voltage & power
voltageValue=resistanceValue*currentValue;
powerValue=(currentValue*currentValue)*resistanceValue;
String voltageValueString = hundred.format(voltageValue);
String powerValueString = hundred.format(powerValue);
voltageBox.setText(voltageValueString);
powerBox.setText(powerValueString);
}
else if(resistanceBox.getText() != null && voltageBox.getText() != null){//finds current & power
currentValue=voltageValue/resistanceValue;
powerValue=(voltageValue*voltageValue)/resistanceValue;
String currentValueString = hundred.format(currentValue);
String powerValueString = hundred.format(powerValue);
currentBox.setText(currentValueString);
powerBox.setText(powerValueString);
}
else if(powerBox.getText() != null && voltageBox.getText() != null){//finds current & resistance
currentValue=powerValue/voltageValue;
resistanceValue=(voltageValue*voltageValue)/powerValue;
String currentValueString = hundred.format(currentValue);
String resistanceValueString = hundred.format(resistanceValue);
resistanceBox.setText(resistanceValueString);
currentBox.setText(currentValueString);
}
else if(currentBox.getText() != null && powerBox.getText() != null){//finds voltage & resistance
voltageValue=powerValue/currentValue;
resistanceValue=powerValue/(currentValue*currentValue);
String resistanceValueString = hundred.format(resistanceValue);
String voltageValueString = hundred.format(voltageValue);
resistanceBox.setText(resistanceValueString);
voltageBox.setText(voltageValueString);
}
else if(resistanceBox.getText() != null && powerBox.getText() != null){//finds voltage & current
voltageValue=Math.sqrt((powerValue*resistanceValue));
currentValue=Math.sqrt(powerValue/resistanceValue);
String currentValueString = hundred.format(currentValue);
String voltageValueString = hundred.format(voltageValue);
currentBox.setText(currentValueString);
voltageBox.setText(voltageValueString);
}
}
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(EnergyForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(EnergyForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(EnergyForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(EnergyForm.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 EnergyForm().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton calculateButton;
private static javax.swing.JTextField currentBox;
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 static javax.swing.JTextField powerBox;
private javax.swing.JButton resetButton;
private static javax.swing.JTextField resistanceBox;
private static javax.swing.JTextField voltageBox;
// End of variables declaration
}
/**
* if(textfield.getText()!=null&&othertextfield.getText()!=null){
*
* }
*/
错误消息:
run: Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1011) at java.lang.Float.parseFloat(Float.java:452) at EnergyForm.getValues(EnergyForm.java:201) at EnergyForm.currentBoxActionPerformed(EnergyForm.java:182) at EnergyForm.access$100(EnergyForm.java:12) at EnergyForm$2.actionPerformed(EnergyForm.java:59) at javax.swing.JTextField.fireActionPerformed(JTextField.java:508) at javax.swing.JTextField.postActionEvent(JTextField.java:721) at javax.swing.JTextField$NotifyAction.actionPerformed(JTextField.java:836) at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1664) at javax.swing.JComponent.processKeyBinding(JComponent.java:2879) at javax.swing.JComponent.processKeyBindings(JComponent.java:2926) at javax.swing.JComponent.processKeyEvent(JComponent.java:2842) at java.awt.Component.processEvent(Component.java:6282) at java.awt.Container.processEvent(Container.java:2229) at java.awt.Component.dispatchEventImpl(Component.java:4861) at java.awt.Container.dispatchEventImpl(Container.java:2287) at java.awt.Component.dispatchEvent(Component.java:4687) at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1895) at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:762) at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1027) at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:899) at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:727) at java.awt.Component.dispatchEventImpl(Component.java:4731) at java.awt.Container.dispatchEventImpl(Container.java:2287) at java.awt.Window.dispatchEventImpl(Window.java:2719) at java.awt.Component.dispatchEvent(Component.java:4687) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729) at java.awt.EventQueue.access$200(EventQueue.java:103) at java.awt.EventQueue$3.run(EventQueue.java:688) at java.awt.EventQueue$3.run(EventQueue.java:686) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87) at java.awt.EventQueue$4.run(EventQueue.java:702) at java.awt.EventQueue$4.run(EventQueue.java:700) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.awt.EventQueue.dispatchEvent(EventQueue.java:699) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138) at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
非常感谢您的帮助!谢谢。
最佳答案
getValues 的前四行都尝试将文本字段中的值转换为 float 。除非所有四个文本字段都有数据，否则至少其中一行将抛出 NumberFormatException。您应该 (1) 在尝试解析 float 之前检查特定文本字段是否不为空，以及 (2) 捕获 NumberFormatExceptions 以处理用户输入无效数据的情况。
关于java - Energy Converter 应用程序无法工作，问题可能出在 getValues 方法中，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15318651/