Scala default parameters
In Scala when sometimes we call certain functions, we do not want to give specific values of the parameters, and want to use their own parameter default values, then you use the definition of default parameters when defining the function.
def sayHello(firstName: String, middleName: String = "William", lastName: String = "Croft") = firstName + " " + middleName + " " + lastName
If the parameter is not given, it will make the right turn from the application parameters
Scala and Java realize the difference between the default parameters
Java：
public void sayHello(String name, int age) {
if(name == null) {
name = "defaultName"
}
if(age == 0) {
age = 18
}
}
sayHello(null, 0)
Scala：
def sayHello(name: String, age: Int = 20) {
print("Hello, " + name + ", your age is " + age)
}
sayHello("leo")
With name parameter
When calling the function, or may not function in accordance with the order defined by the parameters to pass parameters to pass but with use of the parameter name.
sayHello(firstName = "Mick", lastName = "Nina", middleName = "Jack")
You may be mixed with an un-named parameter names and parameters, but not named parameter must be in the front row with parameter name .
sayHello("Mick", lastName = "Nina", middleName = "Jack")