java - 我输入了一个数字，但它给了我错误

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所以我有这些问题，它不会检测 jtextfield 的值。有人可以帮助我吗？

run:
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)

at java.lang.Integer.parseInt(Integer.java:592)
at java.lang.Integer.parseInt(Integer.java:615)
at mypackage.temp_conv.ConvertActionPerformed(temp_conv.java:133)
at mypackage.temp_conv.access$000(temp_conv.java:12)
at mypackage.temp_conv$1.actionPerformed(temp_conv.java:47)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6539)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6304)
at java.awt.Container.processEvent(Container.java:2239)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2297)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4904)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4535)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4476)
at java.awt.Container.dispatchEventImpl(Container.java:2283)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
at java.awt.EventQueue$4.run(EventQueue.java:733)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

构建成功(总时间:5秒)

这是我的代码。

private void ConvertActionPerformed(java.awt.event.ActionEvent evt) {                                        
    // TODO add your handling code here:
    double celsius = Integer.parseInt(cfield.getText());
    double fahren = Integer.parseInt(ffield.getText());
    if(celsius >= 0){
    total = (9/5) * celsius + 32;
    ffield.setText("" + total);
    }
    else if(fahren >= 0){
    total = (5/9) * fahren - 32;
    ffield.setText("" + total);
    }
    cfield.setEditable(false);
    ffield.setEditable(false);

}                                       

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:
    cfield.setText("");
    ffield.setText("");
    cfield.setEditable(true);
    ffield.setEditable(true);

}                 

Answer 1

try {
    double celsius = Double.valueOf(cfield.getText());
    double fahren = Double.valueOf(ffield.getText());
    // do calculations

} catch (NumberFormatException ex) {
    // report the error with a logger
    // or fix the error
    // or escape out 
}