JFrame Text field - Reset if value doesnt equal int?

[FadedAura]

Am programming my GUI and need to reset the text field if the user enters a string.

Part of my current code:

private void diameterTextActionPerformed(java.awt.event.ActionEvent evt) {                                             
        // TODO add your handling code here:
    }

private void DiamFocus(java.awt.event.FocusEvent evt) {
        int d = Integer.parseInt(diameterText.getText());
        if (d >= 1 && d <= 20) {
        } else if (d >= 21 || d <= 0) {
            diameterText.setText("0");
        }
    }

How can I setText back to 0 if user enters anything apart from numbers 1-20.

Thanks.

[Norm]

What happens when you execute your code and try it with different values?

[FadedAura]

If i enter a string, i get:

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "sdfsdf"
at java.lang.NumberFormatException.forInputString(Num berFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:449)
at java.lang.Integer.parseInt(Integer.java:499)
at pipesrus.GUI.LengthFocus(GUI.java:300)
at pipesrus.GUI.access$400(GUI.java:17)
at pipesrus.GUI$5.focusLost(GUI.java:144)
at java.awt.AWTEventMulticaster.focusLost(AWTEventMul ticaster.java:213)
at java.awt.Component.processFocusEvent(Component.jav a:6181)
at java.awt.Component.processEvent(Component.java:604 5)
at java.awt.Container.processEvent(Container.java:204 1)
at java.awt.Component.dispatchEventImpl(Component.jav a:4652)
at java.awt.Container.dispatchEventImpl(Container.jav a:2099)
at java.awt.Component.dispatchEvent(Component.java:44 82)
at java.awt.KeyboardFocusManager.redispatchEvent(Keyb oardFocusManager.java:1850)
at java.awt.DefaultKeyboardFocusManager.typeAheadAsse rtions(DefaultKeyboardFocusManager.java:910)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent (DefaultKeyboardFocusManager.java:568)
at java.awt.Component.dispatchEventImpl(Component.jav a:4524)
at java.awt.Container.dispatchEventImpl(Container.jav a:2099)
at java.awt.Component.dispatchEvent(Component.java:44 82)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.j ava:644)
at java.awt.EventQueue.access$000(EventQueue.java:85)
at java.awt.EventQueue$1.run(EventQueue.java:603)
at java.awt.EventQueue$1.run(EventQueue.java:601)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:87)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:98)
at java.awt.EventQueue$2.run(EventQueue.java:617)
at java.awt.EventQueue$2.run(EventQueue.java:615)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 614)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:122)

I get the code if i enter most symbols however if i enter ; or > for example, the symbol remains. I only want to allow for ints.

[Norm]

xception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "sdfsdf"
at java.lang.NumberFormatException.forInputString(Num berFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:449)
at java.lang.Integer.parseInt(Integer.java:499)
at pipesrus.GUI.LengthFocus(GUI.java:300)

At line 300 in GUI.java you call the parseInt() method with the String: "sdfsdf"
The parseInt method does not think that String is a valid number and throws the NumberFormatException

If you want to handle the case where a user enters bad data, you need to put the parseInt() method inside of a try{} catch block that catches the exception, tells the user about the problem and continues waiting for the user to enter good data.

[DarrylBurke]

First off, for integer input from 1 to 20 I would use a JSpinner. If you absolutely have to accept input in a text component, you could use a JFormattedTextField or a DocumentFilter on a JTextField's Document.

db

[FadedAura]

At line 300 in GUI.java you call the parseInt() method with the String: "sdfsdf"
The parseInt method does not think that String is a valid number and throws the NumberFormatException

If you want to handle the case where a user enters bad data, you need to put the parseInt() method inside of a try{} catch block that catches the exception, tells the user about the problem and continues waiting for the user to enter good data.

Thanks. Just 1 more issue. How can i limit the user to 1 decimal place?

Current code:

private void lengthFocus(java.awt.event.FocusEvent evt) {
        try {
            l = Double.parseDouble(lengthText.getText());
            if (l >= 1 && l <= 20) {
            } else if (l >= 21 || l <= 0) {
                lengthText.setText("0");
            }
        } catch (NumberFormatException ex) {
            lengthText.setText("0");
        }
    }

First off, for integer input from 1 to 20 I would use a JSpinner. If you absolutely have to accept input in a text component, you could use a JFormattedTextField or a DocumentFilter on a JTextField's Document.

db

I would use the JSpinner however i need to allow for users to enter decimals. However i could implement for users Quantity input however is there a way to limit the Spinners values? I only want 1-99 to be selectable.

[Fubarable]

I would use the JSpinner however i need to allow for users to enter decimals. However i could implement for users Quantity input however is there a way to limit the Spinners values? I only want 1-99 to be selectable.

Use a SpinnerNumberModel set with the appropriate parameters:

import javax.swing.*;

public class TestSpinner {
   private static void createAndShowGui() {
      SpinnerNumberModel spinModel = new SpinnerNumberModel(0.0, 0.0, 20.0, 0.1);
      JSpinner spinner = new JSpinner(spinModel);
      
      JPanel mainPanel = new JPanel();
      mainPanel.add(spinner);

      JFrame frame = new JFrame("TestSpinner");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}