CODEWITHSUNDEEP
javaswing
Juan
Juan

Reputation: 532

Deleting all buttons dynamically

I used this answer to add buttons to my GUI dynamically and expected to be able to remove all of them too. To my understanding I am getting all the keys in the HashMap (strings) and then I am doing a for loop over the keys, and deleting them from the hashmap (getting the object back which I will delete). Problem is that after deleting the first button from the hashmap, the loop doesn't continue and my application crashes. 

HashMap<String, JButton> buttonCache = new HashMap<>();
Set<String> names = buttonCache.keySet();
    /*
     * Checking which buttons exist in the hashmap
    */
    for (String name0 : names) {
        System.out.println("Name0: " + name0);
    }

    for (String name1 : names) {
        System.out.println("before removing: " + name1);
        buttonCache.containsKey(name1); //making sure its in it.
        JButton b = buttonCache.remove(name1);
        System.out.println("after removing: " + name1);
        //visualUI.remove(b); //not tested yet
    }
    //visualUI.invalidate();  //not tested yet
    //visualUI.repaint();     //not tested yet

The output is:

Name0: Cancel
Name0: Continue
2
before removing: Cancel
true
after removing: Cancel

Upvotes: 1

Views: 148

Answers (2)

Romain Hippeau
Romain Hippeau

Reputation: 24375

If you want to delete from a HashMap you need to delete with the help of the iterator.
See Calling remove in foreach loop in Java.

EDIT: As per OP... 

Iterator<String> it = names.iterator(); 
while(it.hasNext()) { 
  System.out.println(names); 
  String buttonName = it.next(); 
  JButton b = buttonCache.get(buttonName); 
  it.remove(); 
} 
System.out.println(names);

Upvotes: 1

Phil
Phil

Reputation: 320

Just a guess. When you remove the button from the Hashmap it maybe still be found in UI and doesn't have any reference anymore. Maybe thats one Problem. I see commented lines that should take care of removing the buttons from the UI in your snippit - I guess you should let them do that and see what happens then.

Upvotes: 0

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