Java reflection class private private variable Map and assign

import java.util.LinkedHashMap;
import java.util.Map;

public class MyObj {
    private String KEY = "NAME";

    //目标是通过反射在外部访问cache
    private Map<String, String> cache = new LinkedHashMap<>();

    public MyObj() {
        cache.put(KEY, "fly");
    }

    public void print() {
        System.out.println(cache.get(KEY));
    }
}

import java.lang.reflect.Field;
import java.util.Map;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        MyObj obj = new MyObj();
        System.out.println("反射前");
        obj.print();
        System.out.println("===");

        try {
            Field privateField = MyObj.class.getDeclaredField("cache");
            privateField.setAccessible(true);

            Map map = (Map) privateField.get(obj);

            System.out.println("-");
            Set<String> sets = map.keySet();
            Object[] keys = sets.toArray();
            for (Object k : keys) {
                System.out.println("遍历key-旧值:" + k + "->" + map.get(k.toString()));

                //对MyObj里面的cache设置新值。
                map.put(k, "phil");
            }
            System.out.println("--");


            System.out.println("反射后");
            obj.print();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}

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Java reflection class private private variable Map and assign

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