CODEWITHSUNDEEP
javaswingjbuttonjtextfielddocumentlistener
ColdStormy
ColdStormy

Reputation: 572

Java - Check if JTextField is empty or not

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);
    }

Upvotes: 34

Views: 256146

Answers (13)

Xaice
Xaice

Reputation: 1

You can use

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

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

`

Upvotes: 0

xulo
xulo

Reputation: 540

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

name.getText().isEmpty();

Upvotes: 22

elgijo421
elgijo421

Reputation: 1

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("");
    }
}

Upvotes: 0

Harindu Lakshan
Harindu Lakshan

Reputation: 25

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");
    }
}

Upvotes: -1

Juan-Kabbali
Juan-Kabbali

Reputation: 2414

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();

Upvotes: 2

darijan
darijan

Reputation: 9775

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?

Upvotes: 3

Sijo Jose
Sijo Jose

Reputation: 363

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

Upvotes: 0

user3148337
user3148337

Reputation: 29

use the following code :

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

Upvotes: 2

user3369245
user3369245

Reputation: 71

To Check JTextFiled is empty or not condition:

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

Upvotes: 4

Aneeq Anwar
Aneeq Anwar

Reputation: 1332

Try this

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

Upvotes: 0

sanbhat
sanbhat

Reputation: 17622

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);
    }

  }
});

Upvotes: 39

Nikos
Nikos

Reputation: 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) {
        }

    });

Upvotes: -1

Eng.Fouad
Eng.Fouad

Reputation: 117587

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

Upvotes: 4

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