Component (JList<? extends E> list, E value, int index, boolean isSelected, boolean cellHasFocus) { if (index == -1 && value instanceof String stringValue && !isValid()) { int minLength = getMinLength(); if (getSize().width == 0) { if (stringValue.length() > minLength) { @SuppressWarnings("unchecked") E e = (E)stringValue.substring(0, minLength); value = e; } } } return delegate.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus); }