Aquileo | Scala | Trait Mixins

We can extend several number of scala traits with a class or an abstract class that is known to be trait Mixins. It is worth knowing that only traits or blend of traits and class or blend of traits and abstract class can be extended by us. It is even compulsory here to maintain the sequence of trait Mixins or else the compiler will throw an error. Note:

The Mixins traits are utilized in composing a class.
A Class can hardly have a single super-class, but it can have numerous trait Mixins. The super-class and the trait Mixins might have identical super-types.

Now, lets see some examples.

Extending abstract class with trait Example :

Scala

// Scala program of trait Mixins

// Trait structure
trait Display
{ 

    def Display() 
} 

// An abstract class structure
abstract class Show
{ 
    def Show() 
} 

// Extending abstract class with
// trait
class CS extends Show with Display
{
    
    // Defining abstract class
    // method
    def Display()
    {     
        // Displays output
        println("GeeksforGeeks") 
    } 
    
    // Defining trait method
    def Show()
    {                                     
        // Displays output 
        println("CS_portal") 
    } 
}

// Creating object
object GfG
{ 
    // Main method
    def main(args:Array[String])
    { 
        
        // Creating object of class CS
        val x = new CS() 
        
        // Calling abstract method
        x.Display() 
        
        // Calling trait method
        x.Show() 
    } 
}

Output:

GeeksforGeeks
CS_portal

Here, the correct order of Mixins is that, we need to extend any class or abstract class first and then extend any trait by using a keyword with.

Extending abstract class without trait Example :

Scala

// Scala program of trait Mixins

// Trait structure
trait Text
{ 
    def txt() 
}

// An abstract class structure
abstract class LowerCase
{ 
    def lowerCase() 
} 

// Extending abstract class 
// without trait
class Myclass extends LowerCase
{
    
    // Defining abstract class
    // method
    def lowerCase()
    { 
        val y = "GEEKSFORGEEKS"
        
        // Displays output
        println(y.toLowerCase()) 
    } 
    
    // Defining trait method
    def txt()
    {                                     
    
        // Displays output 
        println("I like GeeksforGeeks") 
    } 
} 

// Creating object
object GfG
{ 
    // Main method
    def main(args:Array[String])
    { 
        
        // Creating object of 'Myclass'
        // with trait 'Text'
        val x = new Myclass() with Text
        
        // Calling abstract method
        x.lowerCase() 
        
        // Calling trait method
        x.txt() 
    } 
}

Output:

geeksforgeeks
I like GeeksforGeeks

Thus, from this example we can say that the trait can even be extended while creating object. Note: If we extend a trait first and then the abstract class then the compiler will throw an error, as that is not the correct order of trait Mixins.

Scala | Trait Mixins

Explore