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 void setKey(K key) {
        this.key = key;
    }
    public V getValue() {
        return value;
    }
    public void setValue(V value) {
        this.value = value;
    }
    public Pair<V, K> swap() {
        return new Pair<>(this.value, this.key);
    }
    @Override
    public String toString() {
        return "(" + key + ", " + value + ")";
    }
    public static void main(String[] args) {
        Pair<String, Integer> original = new Pair<>("Age", 25);
        System.out.println("原始 Pair: " + original);

        // 调用 swap 方法
        Pair<Integer, String> swapped = original.swap();
        System.out.println("交换后 Pair: " + swapped);
    }
}