Programmer Think

Scala variables and data types First of all, the basic data type of Scala is the same as that of Java notes Scala annotations are used exactly like Java Annotation is a good programming habit that a programmer must have. First sort out your thoughts through comments, and then reflect them in code. Basic language method Sin ...

The complete code is at the end. You can jump through the directory 1, Background Assuming that the return value of an HTTP interface is as follows, how can we parse the result using Gson in scala? { "code":0, "message":"OK", "result":[ { "originalityId":7, "conversionType":10011, ...

1. Structural sequence Give the following categories and characteristics as examples trait AA { println("A...") } trait BB extends AA { println("B....") } trait CC extends BB { println("C....") } trait DD extends BB { println("D....") } class EE { println("E...") } class FF extends EE with CC with DD { println("F....") } cla ...

catalogue 1, Variables and constants 2, Identifier Note: scala keyword 3, String 4, Keyboard input 5, Data type  1. Integer type 2. Floating point type 3. Character type 4. Boolean type 5.Unit type, Null type and Nothing type 6, Type conversion 1. Automatic conversion of value type 2. Cast type  3. Conversion between nu ...

About Scala Scala is developed on the basis of Java and runs on the Java virtual machine The syntax structure of Scala is similar to the combination of Java and python If there is only one statement in a line, the semicolon can not be added at the end of the lineUnlike Java, Scala can define global functions independently of classes ...

Scala name passing parameter and value passing parameter Call by name parameterCall by value parameter In Scala, when a parameter calls a function by passing a value, it evaluates the passed in expression or parameter value once before calling the function. However, when calling a function by name, the value of the passed in expression will b ...

Scala package Three functions of Scala package (same as Java) (1) Distinguish between classes with the same name (2) When there are many classes, you can manage classes well (3) Control access scope   It shows that Scala has two package management styles, One method is the same as the package management style of Java. Each source file has a pac ...

Scala is a static type programming language that takes Java virtual machine (JVM) as the running environment and combines the best features of object-oriented and functional programming (static languages need to be compiled in advance, such as Java, c, c + +, and dynamic languages such as js). 1) Scala is a multi paradigm programming language. ...

Idiosyncrasy summary: Sometimes, we will encounter some specific needs, that is, to strengthen the functions of some classes (or objects) without affecting the current inheritance system. For example, there are monkeys and elephants. They all have names, ages and eating functions, but some monkeys learn to ride unicycles after circus tr ...

catalogue Requirements: query a given number of tables, several of which are used in the code Transformation concept: given key Word, several hits in the log file Type selection: Spark parsing keyword list rdd1;Spark parses file directory data rdd2; rdd1 join rdd2(broadcast) Upper Code: Step 1: create SparkContext Step 2: read the file ...