java/w8/Pair.java

public class Pair<K, V> {
    private K key;
    private V value;

    public Pair(K key, V value) {
        this.key = key;
        this.value = value;
    }

    public K getKey() {
        return key;
    }

    public V getValue() {
        return value;
    }

    public void setKey(K key) {
        this.key = key;
    }

    public void setValue(V value) {
        this.value = value;
    }

    public static <K, V> Pair<V, K> swap(Pair<K, V> pair) {
        return new Pair<>(pair.getValue(), pair.getKey());
    }

    @Override
    public String toString() {
        return "Pair{" + "key=" + key + ", value=" + value + '}';
    }

    public static void main(String[] args) {
        Pair<String, Integer> original = new Pair<>("age", 25);
        System.out.println("Original: " + original);
        
        Pair<Integer, String> swapped = Pair.swap(original);
        System.out.println("Swapped: " + swapped);
    }
}