按下按钮后如何检查是否填充了 TextField

Question

I believe my question is pretty simple but i am not really sure if i have the solution to it. The closest i've found to it is something like:

if (exampleTextField.getText().trim().isEmpty()){ ... }

All in all, i want to know how to filter the objects that are created based on that specific fact.

As an example (i'll just say something random, hope it makes sence): I have 2 types of student classes, a class named "UGStudent" for UnderGraduate Students and a class named "PGStudent" for Post Graduate Students. Let's suppose i have a JFrame with some TextFields and one single JButton "Add Student". Let's also suppose that the TextFields i have are 4 : "Last Name", "Full Name", "GPA" and "Graduation Year". When the button is pressed a new object is created and added into a respective ArrayList. So as you'd probably guess, if the field "Graduation Year" is filled we'd like a "PGStudent" to be created, otherwise we'd like a "UGStudent" to be created.

Any suggested solutions?

Answer 1

Not sure of your exact question, but if you're wanting to listen for whether a JTextField's text has been modified, for instance to know whether or not to enable a JButton or its Action, then use a DocumentListener.

Swing, as with most event-driven GUI libraries, has many listener types that will enable you to listen to the state of the components of your GUI.