使用自定义类作为HashMap中的键，但无法搜索键

public class CustomKey {
    private String key;

    public CustomKey(String key) {
        this.key = key;
    }

    // 重写hashCode()方法
    @Override
    public int hashCode() {
        return key.hashCode();
    }

    // 重写equals()方法
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null || getClass() != obj.getClass()) {
            return false;
        }
        CustomKey other = (CustomKey) obj;
        return key.equals(other.key);
    }
}

public class Main {
    public static void main(String[] args) {
        HashMap<CustomKey, String> map = new HashMap<>();
        CustomKey key1 = new CustomKey("key1");
        CustomKey key2 = new CustomKey("key2");

        map.put(key1, "value1");
        map.put(key2, "value2");

        // 通过键搜索值
        String value1 = map.get(key1);
        String value2 = map.get(key2);

        System.out.println(value1);  // 输出：value1
        System.out.println(value2);  // 输出：value2
    }
}