Scala | Trait Mixins

Last Updated : 15 Apr, 2019

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 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
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 :
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.