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JTextField numbers only but can set non-numbers by setText

Restricting JTextField input to IntegersJava JTextField with input hintWhy can't I draw an ellipse with this code?how to perform mouse on click action using threadsDrag and Drop nodes in JTreeJtextField with data validation and BeansbindingGridBagLayout not working correctlyJTextField not clearing after setText(“”)JLabel and JTextField setText is not updateJTextField setText() expensiveConverting String input to Integer from JTextField with Integer.parseInt but still receiving error messageTrying to only allow for numbers to be entered into JTextField and non-numbers be set as 0

0

I want to limit the JTextField to only enter numbers, but I can set the text to non-numbers via setText function.

Because I want to hint when there is no character in the JTextField.
This is the effect I want：When the JTextField does not get the focus, it has a hint text.

This is my code

import javax.swing.*;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
import java.awt.*;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

public class InputFieldFrame extends JFrame implements FocusListener 
 public static void main(String[] args) 
 new InputFieldFrame();
 

 JTextField input = new JTextField(12);

 public InputFieldFrame() 
 //input.setDocument(new NumberFilter()); // Remove the comment can just enter the number, but the hint function will fail.
 //input.setText("Hint Text"); // This will not take effect
 input.addFocusListener(this);
 add(input);
 setSize(new Dimension(200, 200));
 setDefaultCloseOperation(EXIT_ON_CLOSE);
 setVisible(true);
 

 @Override
 public void focusGained(FocusEvent e) 
 if (input.getText().equals("Hint"))
 input.setText("");
 

 @Override
 public void focusLost(FocusEvent e) 
 if (input.getText().equals(""))
 input.setText("Hint");
 

 class NumberFilter extends PlainDocument 
 @Override
 public void insertString(int offs, String str, AttributeSet a) throws BadLocationException 
 if (str.charAt(0) >= '0' && str.charAt(0) <= '9') 
 System.out.println(str);
 super.insertString(offs, str, a);
 
 
 

java swing jtextfield

share|improve this question

edited Mar 7 at 9:12

Grapes

asked Mar 7 at 8:55

GrapesGrapes

175

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  How about you implement an FocusListener which set/unsets the document?
  
  – XtremeBaumer
  Mar 7 at 9:01
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  i update the code that implement the hint function
  
  – Grapes
  Mar 7 at 9:13
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Please refer to stackoverflow.com/questions/1738966/…
  
  – Miller Cy Chan
  Mar 7 at 9:21
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @MillerCyChan Sorry, the way I set the hint is to learn from it, but this reference does not solve my problem (without introducing an external framework)
  
  – Grapes
  Mar 7 at 9:28
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Try this, stackoverflow.com/questions/11093326/…
  
  – Tech Guy
  Mar 7 at 10:52
  

  
  
  
  

 | 
show 2 more comments

0

I want to limit the JTextField to only enter numbers, but I can set the text to non-numbers via setText function.

Because I want to hint when there is no character in the JTextField.
This is the effect I want：When the JTextField does not get the focus, it has a hint text.

This is my code

import javax.swing.*;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
import java.awt.*;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

public class InputFieldFrame extends JFrame implements FocusListener 
 public static void main(String[] args) 
 new InputFieldFrame();
 

 JTextField input = new JTextField(12);

 public InputFieldFrame() 
 //input.setDocument(new NumberFilter()); // Remove the comment can just enter the number, but the hint function will fail.
 //input.setText("Hint Text"); // This will not take effect
 input.addFocusListener(this);
 add(input);
 setSize(new Dimension(200, 200));
 setDefaultCloseOperation(EXIT_ON_CLOSE);
 setVisible(true);
 

 @Override
 public void focusGained(FocusEvent e) 
 if (input.getText().equals("Hint"))
 input.setText("");
 

 @Override
 public void focusLost(FocusEvent e) 
 if (input.getText().equals(""))
 input.setText("Hint");
 

 class NumberFilter extends PlainDocument 
 @Override
 public void insertString(int offs, String str, AttributeSet a) throws BadLocationException 
 if (str.charAt(0) >= '0' && str.charAt(0) <= '9') 
 System.out.println(str);
 super.insertString(offs, str, a);
 
 
 

java swing jtextfield

share|improve this question

edited Mar 7 at 9:12

Grapes

asked Mar 7 at 8:55

GrapesGrapes

175

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  How about you implement an FocusListener which set/unsets the document?
  
  – XtremeBaumer
  Mar 7 at 9:01
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  i update the code that implement the hint function
  
  – Grapes
  Mar 7 at 9:13
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Please refer to stackoverflow.com/questions/1738966/…
  
  – Miller Cy Chan
  Mar 7 at 9:21
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @MillerCyChan Sorry, the way I set the hint is to learn from it, but this reference does not solve my problem (without introducing an external framework)
  
  – Grapes
  Mar 7 at 9:28
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Try this, stackoverflow.com/questions/11093326/…
  
  – Tech Guy
  Mar 7 at 10:52
  

  
  
  
  

 | 
show 2 more comments

I want to limit the JTextField to only enter numbers, but I can set the text to non-numbers via setText function.

Because I want to hint when there is no character in the JTextField.
This is the effect I want：When the JTextField does not get the focus, it has a hint text.

This is my code

import javax.swing.*;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
import java.awt.*;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

public class InputFieldFrame extends JFrame implements FocusListener 
 public static void main(String[] args) 
 new InputFieldFrame();
 

 JTextField input = new JTextField(12);

 public InputFieldFrame() 
 //input.setDocument(new NumberFilter()); // Remove the comment can just enter the number, but the hint function will fail.
 //input.setText("Hint Text"); // This will not take effect
 input.addFocusListener(this);
 add(input);
 setSize(new Dimension(200, 200));
 setDefaultCloseOperation(EXIT_ON_CLOSE);
 setVisible(true);
 

 @Override
 public void focusGained(FocusEvent e) 
 if (input.getText().equals("Hint"))
 input.setText("");
 

 @Override
 public void focusLost(FocusEvent e) 
 if (input.getText().equals(""))
 input.setText("Hint");
 

 class NumberFilter extends PlainDocument 
 @Override
 public void insertString(int offs, String str, AttributeSet a) throws BadLocationException 
 if (str.charAt(0) >= '0' && str.charAt(0) <= '9') 
 System.out.println(str);
 super.insertString(offs, str, a);
 
 
 

java swing jtextfield

share|improve this question

edited Mar 7 at 9:12

Grapes

asked Mar 7 at 8:55

GrapesGrapes

175

import javax.swing.*;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
import java.awt.*;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

public class InputFieldFrame extends JFrame implements FocusListener 
 public static void main(String[] args) 
 new InputFieldFrame();
 

 JTextField input = new JTextField(12);

 public InputFieldFrame() 
 //input.setDocument(new NumberFilter()); // Remove the comment can just enter the number, but the hint function will fail.
 //input.setText("Hint Text"); // This will not take effect
 input.addFocusListener(this);
 add(input);
 setSize(new Dimension(200, 200));
 setDefaultCloseOperation(EXIT_ON_CLOSE);
 setVisible(true);
 

 @Override
 public void focusGained(FocusEvent e) 
 if (input.getText().equals("Hint"))
 input.setText("");
 

 @Override
 public void focusLost(FocusEvent e) 
 if (input.getText().equals(""))
 input.setText("Hint");
 

 class NumberFilter extends PlainDocument 
 @Override
 public void insertString(int offs, String str, AttributeSet a) throws BadLocationException 
 if (str.charAt(0) >= '0' && str.charAt(0) <= '9') 
 System.out.println(str);
 super.insertString(offs, str, a);
 
 
 

share|improve this question

edited Mar 7 at 9:12

Grapes

asked Mar 7 at 8:55

GrapesGrapes

175

share|improve this question

edited Mar 7 at 9:12

Grapes

asked Mar 7 at 8:55

GrapesGrapes

175

asked Mar 7 at 8:55

GrapesGrapes

175

asked Mar 7 at 8:55

GrapesGrapes

175