java

That method, removeElement(…) is part of the DefaultListModel, not the JList. You need to first call getModel() on the JList, cast it to the DefaultListModel (after first checking that it is this type) and then call the method. e.g., ListModel model = list.getModel(); if (model instanceof DefaultListModel && list.getSelectedValue() != null) { ((DefaultListModel) model).removeElement(list.getSelectedValue()); } … Read more

Strictly speaking, this is a compiler warning (not an error). It’s technically “legal” to have variables you don’t actually use, but the compiler’s telling you that it’s probably a mistake. In this case, as others have indicated, you assign a value to amount but you never actually do anything with it. As a general tip, … Read more

Create an array: String[] colors = {“red”, “blue”, “white”}; Generate a random number between 0 and 2: Random rand = new Random(); int random = rand.nextInt((2 – 0) + 1); Get the random color: String randomColor = colors[random]; solved Random colour generation

You can nest JMenu within other instances of JMenu, and you can add a JMenuItem to a JMenu, but you can’t add a JMenuItem to another JMenuItem. Think about that… what did you expect that to do? A leaf, for example, grows from a branch, not from another leaf. JMenu menu = new JMenu(“Main Menu”); … Read more