重写Map.get方法

import java.util.HashMap;
import java.util.Map;

public class CustomMap<K, V> extends HashMap<K, V> {

    @Override
    public V get(Object key) {
        // 在获取值之前进行一些额外的操作
        System.out.println("Performing additional operations before getting the value.");

        // 调用父类的get方法获取值
        V value = super.get(key);

        // 在获取值之后进行一些额外的操作
        System.out.println("Performing additional operations after getting the value.");

        return value;
    }

    public static void main(String[] args) {
        CustomMap<String, Integer> map = new CustomMap<>();
        map.put("key1", 1);
        map.put("key2", 2);

        // 调用重写的get方法
        Integer value = map.get("key1");
        System.out.println("Value: " + value);
    }
}