03 fastjason solves circular references

FastJson Solve circular references

The reasons causing In the object to be converted There are two references with the same address

Code display ：

public static void main(String[] args) {
    
        ArrayList<Object> list = new ArrayList<>();
        Object o = new Object();
        list.add(o);
        list.add(o);
    	//  Output length 
        System.out.println(list.size());
    	//  convert to json Result of character 
        System.out.println(JSONObject.toJSONString(list));
    	
}

The results show that , Converted json String is not what we want , The general reason for the problem is fastjson During the conversion , It is found that there is already a reference to this location , So the later one points to the previous reference , So how to solve this problem ？

//  Solve circular references 
System.out.println(JSONObject.toJSONString(list,SerializerFeature.DisableCircularReferenceDetect));
   

You can see Now we have successfully solved the problem of circular reference