I was facing two different stack traces (see below) when trying to serialize my ESRBRating object which is a JPA entity. I am using Spring Data JPA. The controller called the service, service called the repository. I was able to resolve the issue by adding @Proxy(lazy = false) on my ESRBRating object. My main…
Tag: java
Ignoring upper case and lower case in Java
I want to know how to make whatever the user inputs to ignore case in my method: Answer You have to use the String method .toLowerCase() or .toUpperCase() on both the input and the string you are trying to match it with. Example:
How to get Cartesian product from multiple lists?
Say I have several List<T>s, I will put them into another list or other collections, so I don’t know how many list<T> I have until I call List<List<T>>.size() Take below List<Integer> as an example: How can I get the result of list1*list2*list3*…listn as a Cartesian p…
Switching between different JDK versions in Windows
I’m working on few projects and some of them are using different JDK. Switching between JDK versions is not comfortable. So I was wondering if there is any easy way to change it? I found 2 ways, which should solve this problem, but it doesn’t work. First solution is creating a bat files like this:…
Fragments inside LinearLayout – Android
I’m new with fragments and I try to use these. My xml from activity is: And I want to change the fragment inside of LinearLayout, my class of mainActivity is: And my PlaceHolderFunctions are: Why doesn’t work when I press the button? What do I doing bad? Srry for my english and thanks in advance! …
Java, comparing a Linked List to an Array
Working on a Java program that will read in two different passages, convert both strings to arrays of strings for each word, and then String One to a linked list, which will promptly be sorted into alphabetical order. After the list has been sorted, I get confused. I have a for loop written to get the length …
What state is a sleeping thread in?
I’m looking for verification/arguments on the following: A thread is in exactly one of the 5 (+1 — 2 for WAITING) states at any point of time. Suppose a thread T calls Thread.sleep(3000); and thus puts itself into sleep for 3 secs. Which state is it in during those 3 secs? It’s clearly start…
Convert Java object to XML string
Yes, yes I know that lots of questions were asked about this topic. But I still cannot find the solution to my problem. I have a property annotated Java object. For example Customer, like in this example. And I want a String representation of it. Google reccomends using JAXB for such purposes. But in all exam…
Multiple assignment at once in java
In python you can do this: Is there an equivalent in java? Answer tl;dr: No, there isn’t such a thing in Java. You can assign initial values to variables like this: But if your want (1, 2, 3) to be the result of a method call, this is not possible in Java. Java does not allow returning multiple values. …
Using WatchService in JAVA. Can I watch subdirectory at the same time?
In JAVA I will watch directory by using WatchService. For example if I watch /users/monitor, WatchService can watch only one directory. But I wanna watch every subdirectory ‘at the same time’ How can I code? T_T —————————code——̵…