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The code below keeps giving a java.lang.NumberFormatException: empty String:
private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {
double AText = Double.parseDouble(angleAField.getText());
double BText = Double.parseDouble(angleBField.getText());
double CText = Double.parseDouble(angleCField.getText());
double aText = Double.parseDouble(sideaField.getText());
double bText = Double.parseDouble(sidebField.getText());
double cText = Double.parseDouble(sidecField.getText());
if (getMissing(angleAField.getText()) == false && getMissing(angleCField.getText()) == false) { //doesnt have angle C ,find Angle A
double angleA = Math.round(Math.asin((Math.sin(BText) / bText) * aText));
angleAField.setText("" + angleA);
}
}
public boolean getMissing(String Field) {
try {
if (Field.equals("")) {
return false; // has number
}
} catch (NumberFormatException e) {}
return true;
}
Error:
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1011)
at java.lang.Double.parseDouble(Double.java:540)
at sowhatstrig.trigFrame.jButton4ActionPerformed(trigFrame.java:520)
at sowhatstrig.trigFrame.access$300(trigFrame.java:20)
at sowhatstrig.trigFrame$4.actionPerformed(trigFrame.java:353)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
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:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
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.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:723)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:682)
at java.awt.EventQueue$3.run(EventQueue.java:680)
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:696)
at java.awt.EventQueue$4.run(EventQueue.java:694)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:693)
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)
622
NumberFormatException: For input string: "null" is specifically saying that the String you receive for parsing is not numeric and it's true, "null" is not numeric. Many Java methods which convert String to numeric type like Integer. parseInt() which convert String to int, Double.
The NumberFormatException is an unchecked exception in Java that occurs when an attempt is made to convert a string with an incorrect format to a numeric value. Therefore, this exception is thrown when it is not possible to convert a string to a numeric type (e.g. int, float).
There are three ways to convert a String to double value in Java, Double. parseDouble() method, Double. valueOf() method and by using new Double() constructor and then storing the resulting object into a primitive double field, autoboxing in Java will convert a Double object to the double primitive in no time.
The NumberFormatException occurs when an attempt is made to convert a string with improper format into a numeric value. That means, when it is not possible to convert a string in any numeric type (float, int, etc), this exception is thrown. It is a Runtime Exception (Unchecked Exception) in Java.
You should check your field before parse double:
private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {
double AText = ParseDouble(angleAField.getText());
double BText = ParseDouble(angleBField.getText());
double CText = ParseDouble(angleCField.getText());
double aText = ParseDouble(sideaField.getText());
double bText = ParseDouble(sidebField.getText());
double cText = ParseDouble(sidecField.getText());
// other code here same
}
double ParseDouble(String strNumber) {
if (strNumber != null && strNumber.length() > 0) {
try {
return Double.parseDouble(strNumber);
} catch(Exception e) {
return -1; // or some value to mark this field is wrong. or make a function validates field first ...
}
}
else return 0;
}
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