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

User · Answer

if name getText   hashCode      0       JOptionPane showMessageDialog null   not empty      else      JOptionPane showMessageDialog null   empty

User · Answer

use the following code    if name getText   equals        loginbt disable

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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    gt   1                    button setEnabled true                 else                   button setEnabled false                                     Override         public void keyReleased KeyEvent e

User · Answer

To Check JTextFiled is empty or not condition   if   billnotf getText   length    0    billtabtf getText   length    0

User · Answer

Try this  if name getText      null  amp  amp  name getText   equals                loginbt setEnabled false     else           loginbt setEnabled true

User · Answer

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

User · Answer

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

[java] Java - Check if JTextField is empty or not

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