Why does the Spring Core project use Spring Boot (STS)?

I'm using Spring Tool Suite and learning Spring. I've created a Spring Start Project. The project wizard ask for the version of Boot. I'm just practicing Spring and doing output to the console. Why do I need Spring Boot? There's not way to create a s

Path to Firebase admin key in the Java servlet

I keep getting a FileNotFoundException when trying to initialize my app with Firebase saying it cannot find my adminsdk.json service key. This is a specific error as I am trying to initialize Firebase in an Android Module Servlet. Here is what my mod

Java table - (parallel table)

I am struggling with Arrays (java) Since this is the first time to learn about java in my life, I have no idea how to start it. I have just learned how to declare arrays and so on. However, this is too complicated for me. I think I can get guidelines

Java global variables can not be modified android studio

I don't know if I'm doing this correctly, I made a java file var.java public class var { public static boolean u = true ; } in the main activity I have buUn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //var

singletons faster than static classes in Java?

I need to heavily optimize a piece of java code to the point that I'm wondering if I should use local variables in methods, singletons with private variables or "static classes with all static variables. NOTE: I never read these variables, I initiali

NullPointerException from empty table cells

Using Java and no IDE, but rather the command line, I'm supposed to write a basic-ish phone book program focusing around arrays in which the user has three options: search for a name in an array and print the name and phone number if the name is foun

Private methods or internal class

I am working on a class which needs couple of helper methods. This methods are going to be used only by this class. So I am wondering which will be best practice i.e. whether declaring these helper methods as private methods or group them and put ins

Second servlet in the project does not work

I am new to Servlets. I made a simple project with 2 jsp files. and two Servlers jsp1, jsp2, servlet1 and servlet2. When the code in both jsps' body tags is this (Both points to servlet1 ) <form method="post" action="servlet1"> &

Deserializing objects with a pointer

I am trying to deserialize the 9 objects of the class Planet which are stored on the planetobject.txt file: But it gives me error that says: java.io.InvalidClassException: Planet; local class incompatible: stream classdesc serialVersionUID = -1020679

java.lang.NoSuchMethodException when running jar in code

I've got a problem when trying to execute specific jar files in code. My objective was to create GUI application (wizard) in which user selects various xml files, selects a jar file to execute and provide it with input xml. To execute jar, I use this

Javax.el, ELResolver: Solving Dependencies Between Variables

iam building a small application to work with variables. The first step is to resolve simple dependencies between variables. I can not get things to run properly. I can resolve very simple declarations like a=10, but it always fails if it gets a litt

call to the primitive JPA method throws WrongClassException

public static UserDetail UserDetail.findUserDetail(Long id) { if (id == null) return null; return entityManager().find(UserDetail.class, id); } We are using spring Roo. Above is Roo generated finder method. Partial stack trace is as follows: Caused b

add items from the list to the string array

I have a String array like, String[] abc= new String[]{}; and my List has some values. I iterate the list and add each list element to string array. for(int i=0; i<errList.size(); i++) { abc[i] = errList.get(i).getSrceCd(); } errList.size() has 6 val

The program compiles but does not work

This is an assignment i have to complete. Can someone lead me in the right direction? The program compiles but wont run correctly. The error is InputMissmatch exception.Your problem is that you are entering a letter into a float field. In your progra

How can System.out.format prevent blocking?

I've found that including a call to System.out.format in the classic Java Deadlock Tutorial will prevent deadlock from occurring, and I can't figure out why. The code below is the same as that of the tutorial, with the addition to main of System.out.

Comparison of existing files not as expected

I am trying to compare the contents of a file with a String object. But even though the contents are same, it is telling that the contents are different and adding the same contents again and again. For every run of this code, same content is rewritt

Random number generator to cover all the numbers in the set

I am writing an Android app and I want to generate random numbers. But, Java's RandomGenerator gives me only pseudo random numbers. The numbers repeat and not all the numbers are covered. I want something that will give me non-repeating numbers and w

Replacement for huge case reports

I'm trying to improve a Java project which uses a lot of large case statements. In cases where the case statement is used, it is used to handle an event which has an attribute associated to it. For example: public void jumpOverWall(int wallID) { swit

Generic viewer for paged SELECT sql queries

I am creating a web page where user can select datasource and execute select statements and see the paginated results in table. Now for pagination i am wrapping queries to get total row count and rownum to fetch a particular block of rows. As we add

Java: Merging InputStreams

My goal is to create (or use existing) an InputStream implementation (say, MergeInputStream) that will try to read from a multiple InputStreams and return the first result. After that it will release lock and stop reading from all InputStreams until

JPA or Hibernate with Oracle table partitions?

I need to use an Entity framework with my application, and I have used table - partitions in Oracle database. With simple JDBC, I am able to select data from a specific partition. But I don't know whether I can do the same with hibernate or Eclipse l