如何检测JTextField是否为空？

Question

I have made a chat client application and I am stuck on the login dialog. Basically, I want the register button event to detect whether the user entered anything into the field box. This code isn't working.

 public class RegButtonListener implements ActionListener { public void actionPerformed(ActionEvent event) { if(userBox.getText() != null) { System.out.println("Lol"); } } } 

Answer 1

TRy this code

public class RegButtonListener implements ActionListener
{
    public void actionPerformed(ActionEvent event)
    {
        if(event.getSource == userBox) {
           if(!userBox.getText().isEmpty())
           {
            System.out.println("Lol");
           }
        }
    }
}

Answer 2

You can check if it's empty (in this case, not empty) in two ways: using isEmpty( ) or equals("")

if (!userBox.getText().isEmpty()){
    //code
}

or

if (!userBox.getText().equals("")){
    //code
}

Answer 3

Try this..

 if(!userBox.getText().equals("")) { System.out.println("ABC"); }