How to make a Textboxt empty validation in Java

Question

I want to make a validation when the user clik the jbutton1 if the textboxt field empty the jlabel value will show "Input name cannot be empty". I'm beginner.

Here my false code :

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                      
        if(jTextField1.text == ""){
        jLabel1.setText("Input name cannot be empty");
        }else{
        jLabel1.setText("My name : " + jTextField1.getText() + ". Selamat datang di java .");
    }

Use `.equals` method to compare String. – Kaustubh Khare Mar 19 '18 at 05:16 — Kaustubh Khare, Mar 19 '18 at 05:16

score 1 · Answer 1 · answered Mar 19 '18 at 05:17

Use equals() instead of == as-

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                      
    if(jTextField1.equals(""){
    jLabel1.setText("Input name cannot be empty");
    }else{
    jLabel1.setText("My name : " + jTextField1.getText() + ". Selamat datang di java .");
}

score 1 · Answer 2 · edited Mar 19 '18 at 13:45

1

Avoid using == as it is not correct. isEmpty() method will do the trick. Make sure to trim(); for removing any white spaces beforehand. Try to use this :

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                      
    if(jTextField1.getText().trim().isEmpty()){
        jLabel1.setText("Input name cannot be empty");
    } else {
        jLabel1.setText("My name : " + jTextField1.getText() + ". Selamat datang di java .");
    }
}

edited Mar 19 '18 at 13:45

GGO

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answered Mar 19 '18 at 05:19

Kevin

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1

Sure will do. Thanks GGO for informing. – Kevin Mar 19 '18 at 08:57

Kaustubh Khare · Answer 3 · 2018-03-19T05:27:56.867

Use .equals() method of String instead of ==. To get Text from jTextField1 use getText() method.

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                      
    if(jTextField1.getText().equals(""){
    jLabel1.setText("Input name cannot be empty");
    }else{
    jLabel1.setText("My name : " + jTextField1.getText() + ". Selamat datang di java .");
}

Check this What is the difference between == vs equals() in Java?

score 0 · Answer 4 · answered Mar 19 '18 at 05:24

First, you need to replace all whitespace to check if the input has any characters and then compare the length or using .equals():

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {  
    String text = jTextField1.getText().replaceAll("\\s+","");
    if(text.length() <= 0){
    jLabel1.setText("Input name cannot be empty");
    }else{
    jLabel1.setText("My name : " + jTextField1.getText() + ". Selamat datang di java .");
}

How to make a Textboxt empty validation in Java

4 Answers4