I’m trying to write an app that helps you manage your finances. I’m using an EditText Field where the user can specify an amount of money. I set the inputType to numberDecimal which works fine, except that this allows people to enter numbers such as 123.122 which is not perfect for money. Is there…
ResultSetMetaData getScale returns 0
I have a table called RATE_HISTORY with a field called RATE. The RATE field has scale 18. I am using ResultsetMetaData to get meta-data of columns in this table on Oracle 11.2. I execute the following …
What is the most efficient way to access particular elements in a SortedSet?
I want to use a collection that is sorted, but one in which I can access elements by index, i.e. I want something that has characteristics of both a Set and a List. Java.util.TreeSet comes real close to what I need, but doesn’t permit access via an index. I can think of several options: I could iterate …
What is the simplest way to draw in Java?
What is the simplest way to draw in Java? This doesn’t work and I have no idea how to get anything to appear. Answer Easiest way: You simply need to extend JPanel and override the paintComponent method of the panel. I’d like to reiterate that you should not be overriding the paint method. Here is …
Intersection and union of ArrayLists in Java
Are there any methods to do so? I was looking but couldn’t find any. Another question: I need these methods so I can filter files. Some are AND filters and some are OR filters (like in set theory), so I need to filter according to all files and the unite/intersects ArrayLists that holds those files. Sho…
How does Hibernate detect dirty state of an entity object?
Is it using some kind of byte codes modification to the original classes? Or, maybe Hibernate get the dirty state by compare the given object with previously persisted version? I’m having a problem with hashCode() and equals() methods for complicated objects. I feel it would be very slow to compute hash…
What is better: multiple “if” statements or one “if” with multiple conditions?
For my work I have to develop a small Java application that parses very large XML files (~300k lines) to select very specific data (using Pattern), so I’m trying to optimize it a little. I was wondering what was better between these 2 snippets: OR Other details: These if statements are executed on each …
Hibernate : How override an attribute from mapped super class
The generic entity, super class: The pojo: I try to use thoses annotations : @AttributeOverride, @Id, … but It doesn’t work. Can you help me? I want to override the attribute “id” to specify another column name and a sequence by pojo/table. What is the best way to do that? Answer Try t…
Adding whitespace in Java
There is a class trim() to remove white spaces, how about adding/padding? Note: ” ” is not the solution. Answer I think you are talking about padding strings with spaces. One way to do this is with string format codes. For example, if you want to pad a string to a certain length with spaces, use s…
Set running time limit on a method in java
I have a method that returns a String. Is it possible that after a certain time, if threshold is excedeed for that method, to return some specific string? Answer The Guava library has a very nice TimeLimiter that lets you do this on any method that’s defined by an interface. It can generate a proxy for …