As a quick note, here’s the source code for a Java “approximately equal” function that I use in an Android application:
After working with Scala for a long time, I had to come back to Java for a while to work on an Android app. Right away I missed a lot of things from the Scala world, including all of the built-in Scala collection methods, and other things as simple as the Scala
If you haven’t used them before, a Scala
Tuple class lets you write code like this:
Tuple<String, Integer> t = new Tuple<>("age", 41);
If you’re comfortable with generics, the Java implementation of a
Tuple class like this is simple:
This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 4.15, “How to define an
equals method (object equality) in Scala.”
You want to define an equals method for a Scala class so you can compare object instances to each other.
This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 4.14, “How to generate boilerplate code with Scala case classes.”
Scala FAQ: How do I find the unique items in a
Vector, or other Scala sequence?
Solution: Use the
Here's a simple example using a
List of integers:
scala> val x = List(1,1,1,2,2,3,3) x: List[Int] = List(1, 1, 1, 2, 2, 3, 3) scala> x.distinct res0: List[Int] = List(1, 2, 3)
As you can see,
res0 now contains only the unique elements in the list.
Java String comparison FAQ: Can you share some examples of how to compare strings in Java?
If you’re like me, when I first started using Java, I wanted to use the
== operator to test whether two
String instances were equal, but that’s not the correct way to do it in Java.
Scala String FAQ: How do you compare string equality in Scala?
In Scala you compare two Strings with the
== operator. This is different than Java, where you compare two Strings with the
For example, given these strings:
While working with various "Java instanceof" tests recently, my curiosity was piqued, and I thought I'd take a look at how the instanceof operator works when testing against a Java array.
You might think that when the Java
instanceof operator is used to test a
null reference, such as a
null reference to a String,
instanceof would realize that even though the reference is currently
null, it is a reference to a
String, so you might expect
instanceof to return
true ... but it doesn't.
Perl equality FAQ: Can you share a list of the Perl equality operators?
Sure. Here's a convenient list of the Perl comparison operators (also known as Perl equality operators, equal, or not equal operators).
The Perl comparison operators are different for numeric and string comparison tests, as you can see in the following table: