java Object 与String、Boolean、List、Date、Number类型相互转换

 应用场景：创建一个类这个类有个Map 属性，但是Object类型只能指定String、Boolean、List、Date、Number

代码如下：

  public static class Builder {
        private Map propertyMap = new HashMap();
       
        private Builder() {
        }

        public EventRecord build(){
         
            return new EventRecord(propertyMap);
        }


        public EventRecord.Builder addProperty(String key, String property) {
            addPropertyObject(key, property);
            return this;
        }

        public EventRecord.Builder addProperty(String key, boolean property) {
            addPropertyObject(key, property);
            return this;
        }

        public EventRecord.Builder addProperty(String key, Number property) {
            addPropertyObject(key, property);
            return this;
        }

        public EventRecord.Builder addProperty(String key, Date property) {
            addPropertyObject(key, property);
            return this;
        }

        public EventRecord.Builder addProperty(String key, List property) {
            addPropertyObject(key, property);
            return this;
        }

        private void addPropertyObject(String key, Object property) {
            if (key != null) {
                propertyMap.put(key, property);
            }
        }
    }

此类不允许外部创建只能build出对象，参数不允许set,只能调用addProperty()初始化相应的类型 

//        Object value = "asdhgashga";
//        Object value = new Date();
//        Object value = true;
//        Object value = 1241235132461l;
        Object value = new ArrayList(){{
            add("1");
            add("4");
            add("5");
        }};
        if(value instanceof String){
            System.out.println((String)value);
        }else if(value instanceof Boolean){
            System.out.println((Boolean)value);
        }else if(value instanceof Number){
            System.out.println((Number)value);
        }else if(value instanceof Date){
            System.out.println((Date)value);
        }else if(value instanceof ArrayList){
            List result = new ArrayList<>();
            for (Object o : (List) value) {
                result.add(String.class.cast(o));
            }
            System.out.println(result);
        }