CODEWITHSUNDEEP
javaswingactionlistenerinvokeandwait
PM 77-1
PM 77-1

Reputation: 13334

How to implement a loop logic in a Swing application?

My title is somewhat cryptic but I couldn't come up with a clear one.

First, two code snippets to establish a point of reference (hopefully I have no typos):

Input with Scanner

'''
Scanner sc = new Scanner(System.in);
for (int i=0; i<10; ++ i)  {
  System.out.print("Please input a value:");
  String answer = sc.next();
  // do something with this string
}  
...

Input with JOptionPane:

...
for (int i=0; i<10; ++ i) {
   String answer = JOptionPane.showInputDialog("Please input a value");
   // do something with this string
{

So, in the above samples we're asking a user to enter a value a fixed number of times. How can I implement the same kind of functionality in a Swing application?

I have no problem creating a JFrame with JPanel (as its content pane) and adding JLabel (with prompt) and JTextField to this panel. I can also create ActionListener for the text field which ActionPerformed method to retrieve the value and process it. String processing is not a long-running task so I do not believe I will need a separate worker thread.

Since we can't really force user to do anything, I plan to use javax.swing.Timer to ensure a timely response.

What I do not understand is how to implement the loop or any other form of control to ensure that a user enters (and the program retrieves) the value the exact number of times. How do I inject such logic into an event-driven system?

Once I set-up the GUI part and submit its instance to be invoked on EDT I seem to be relinquishing all control.

Do I initially submit my text field with setEditable set to false and then create a loop that will invokeAndWait a Runnable to enable the edit (and disable it back in the ActionPerformed)?

Please point me into the right direction.

Upvotes: 1

Views: 168

Answers (1)

MadProgrammer
MadProgrammer

Reputation: 347234

Well it depends on how you want to achieve it...

You could...

Provide the required number of fields (10 in your example) and a JButton, so that until all the fields are filled out, clicking the button will simply provide the user with a message and re-focus the invalid field...

You could...

Provide the user with a single field (and label) and button. Until they fill out the field, pressing the button prompts them and re-focuses the field.

When the user fills out the required information and clicks the button, you increment a counter, reset the field and carry on until your counter reaches it's limit...

You could...

Use a JTable which has only one column and five rows...this is simplified (depending on your perspective) solution to the first solution...

Upvotes: 5

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