package org.example.testmap;

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

public class Main {

    public static void main(String[] args) {

        Param p = new Param();

        // 异常
        int o1 = p.get("1");

        // 正常
        Integer o2 = p.get("2");
        System.out.println(o2); // null
    }

    static class Param {
        private final Map<String, Object> m = new HashMap<>();

        public <K> K get(String key) {
            return (K) m.get(key);
        }
    }
}