Java - Check if JTextField is empty or not

Question

So I got know this is a popular question and already found the solution. But when I try this it doesn't work properly.

My JTextField is empty and the button isn't enabled. When I write something in my textfield the button doesn't get enabled.

So my program should check this field every second whether it's empty or not. As soon as someone writes something into the textfield the button should be enabled.^^

loginbt = new JButton("Login");
    loginbt.addActionListener(new loginHandler());
    add(loginbt);

    if(name.getText().equals("")) {
        loginbt.setEnabled(false);
    }else {
        loginbt.setEnabled(true);
    }

BTW, I'll use `loginbt.setEnabled(name.getText().length()!=0);` — johnchen902, Jun 16 '13 at 10:52

score 38 · Accepted Answer · edited May 23 '17 at 10:29

38

For that you need to add change listener (a DocumentListener which reacts for change in the text) for your JTextField, and within actionPerformed(), you need to update the loginButton to enabled/disabled depending on the whether the JTextfield is empty or not.

Below is what I found from this thread.

yourJTextField.getDocument().addDocumentListener(new DocumentListener() {
  public void changedUpdate(DocumentEvent e) {
    changed();
  }
  public void removeUpdate(DocumentEvent e) {
    changed();
  }
  public void insertUpdate(DocumentEvent e) {
    changed();
  }

  public void changed() {
     if (yourJTextField.getText().equals("")){
       loginButton.setEnabled(false);
     }
     else {
       loginButton.setEnabled(true);
    }

  }
});

edited May 23 '17 at 10:29

Community

1
1

answered Jun 16 '13 at 10:47

sanbhat

17,522
6
48
64

I wanted to ask whether the procedure changes if the button were to depend on more than 1 text field. Would I use the same logic to define the action or is there some other way with less code? Thanks for your time!! – boxed__l Jan 13 '14 at 22:27
Then you create one `DocumentListener` implementation which handles that button and add them as listeners to all the textboxes? – sanbhat Jan 14 '14 at 05:15
yes..thanks..forgot basic stuff: [how to write document listener](http://docs.oracle.com/javase/tutorial/uiswing/events/documentlistener.html) – boxed__l Jan 14 '14 at 12:11

score 22 · Answer 2 · edited Jun 01 '22 at 19:35

22

The following will return true if the JTextField name does not contain text:

name.getText().isEmpty();

edited Jun 01 '22 at 19:35

loggeek

123
1
9

answered Feb 01 '15 at 08:24

xulo

440
3
9

score 4 · Answer 3 · answered Jun 16 '13 at 10:48

4

What you need is something called Document Listener. See How to Write a Document Listener.

answered Jun 16 '13 at 10:48

Eng.Fouad

115,165
71
313
417

score 4 · Answer 4 · edited Mar 01 '14 at 20:45

4

To Check JTextFiled is empty or not condition:

if( (billnotf.getText().length()==0)||(billtabtf.getText().length()==0))

edited Mar 01 '14 at 20:45

László Papp

51,870
39
111
135

answered Mar 01 '14 at 20:23

user3369245

71
2

Nice. I like this. – Boris Karloff Jan 04 '21 at 20:22

darijan · Answer 5 · 2016-10-15T17:30:15.863

3

Well, the code that renders the button enabled/disabled:

if(name.getText().equals("")) {
    loginbt.setEnabled(false);
}else {
    loginbt.setEnabled(true);
}

must be written in javax.swing.event.ChangeListener and attached to the field (see here). A change in field's value should trigger the listener to reevaluate the object state. What did you expect?

edited Oct 15 '16 at 17:30

answered Jun 16 '13 at 10:48

darijan

9,725
25
38

score 2 · Answer 6 · answered Nov 10 '14 at 03:10

2

use the following code :

if(name.getText().equals(""))
{
loginbt.disable();
}

answered Nov 10 '14 at 03:10

user3148337

29
3

score 2 · Answer 7 · answered Oct 29 '19 at 19:20

you can use isEmpty() or isBlank() methods regarding what you need.

Returns true if, and only if, length() is 0.

this.name.getText().isEmpty();

Returns true if the string is empty or contains only white space codepoints, otherwise false

this.name.getText().isBlank();

score 0 · Answer 8 · answered Jun 16 '13 at 11:05

0

Try this

if(name.getText() != null && name.getText().equals(""))
{
        loginbt.setEnabled(false);
}
else
{
        loginbt.setEnabled(true);
}

answered Jun 16 '13 at 11:05

Aneeq Anwar

1,282
7
20

score 0 · Answer 9 · edited Apr 09 '15 at 20:23

0

if(name.getText().hashCode() != 0){
    JOptionPane.showMessageDialog(null, "not empty");
}
else{
    JOptionPane.showMessageDialog(null, "empty");
}

edited Apr 09 '15 at 20:23

mathielo

6,725
7
50
63

answered Apr 09 '15 at 19:42

Sijo Jose

363
1
3
10

Cold you please explain why you think that this is a solution? – Trinimon Apr 09 '15 at 20:06

score 0 · Answer 10 · answered May 30 '22 at 08:56

Try this one and change booleans statements around.

String text = name.getText(); 
if(!text.isEmpty()) {
    loginbt.setEnabled(true);
}else {
    loginbt.setEnabled(false);
}

In my action method it worked fine.

public void actionPerformed(ActionEvent e){
    String inputText = e.getActionCommand();
    String itext = text1.getText();
    if(inputText.equals("Submit") && !itext.isEmpty()){
        label1.setText(text1.getText());
        text1.setText("");
    }
}

score -1 · Answer 11 · answered Jun 16 '13 at 10:58

-1

Try with keyListener in your textfield

jTextField.addKeyListener(new KeyListener() {

        @Override
        public void keyTyped(KeyEvent e) {
        }

        @Override
        public void keyPressed(KeyEvent e) {
            if (text.getText().length() >= 1) {
                button.setEnabled(true);
            } else {
                button.setEnabled(false);
            }
        }

        @Override
        public void keyReleased(KeyEvent e) {
        }

    });

answered Jun 16 '13 at 10:58

Nikos

1

1

-1 A DocumentListener is the preferred approach. There is rarely a reason to use a KeyListener. That is old design when using AWT. Also the code would not work anyway because no text has been added to the Document when the keyPressed event is generated, so the length will still be 0 when the first event is fired. – camickr Jun 16 '13 at 16:39
1

Thanks for the correction,i will see the DocumentListener in the future – Nikos Jun 16 '13 at 19:47

score -1 · Answer 12 · edited Dec 21 '19 at 12:47

-1

private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // Submit Button        

    String Fname = jTextField1.getText();
    String Lname = jTextField2.getText();
    String Desig = jTextField3.getText();
    String Nic = jTextField4.getText();
    String Phone = jTextField5.getText();
    String Add = jTextArea1.getText();
    String Dob = jTextField6.getText();
    // String Gender;
    // Image

    if (Fname.hashCode() == 0 || Lname.hashCode() == 0 || Desig.hashCode() == 0 || Nic.hashCode() == 0 || Phone.hashCode() == 0 || Add.hashCode() == 0)
    {
        JOptionPane.showMessageDialog(null, "Some fields are empty!");
    }
    else
    {
        JOptionPane.showMessageDialog(null, "OK");
    }
}

edited Dec 21 '19 at 12:47

סטנלי גרונן

2,917
23
46
68

answered Dec 21 '19 at 12:17

Harindu Lakshan

25
3

Hi @HarinduLakshan, please consider adding more information to improve the quality of the answer. – Tiago Martins Peres Dec 21 '19 at 12:43
This answer has multiple issues. It doesn't clearly address the question, the variable names don't adhere to Java conventions, and it uses hashCode() rather than isEmpty() to check for missing values. It also contains unnecessary comments. – Greg Brown Nov 27 '22 at 14:04

Java - Check if JTextField is empty or not

12 Answers12

Linked

Related