scala - Extending new instance of a class -

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hi trying understand code below scala. have class b, , has dependency class b. class c extends a. when extending class code below newing b. significant of doing this? in java can't this. 

  class b {}   class a( b:b ) {}   class c extends a( new b) {}

what b?

class b {}

this empty class. in java, write same.

what a?

class a(b: b) {}

this class 1 field. constructor of class takes 1 argument. constructor sets field argument. in java, write follows:

class {   b b   a(b b) {     this.b = b   } }

what c?

class c extends a(new b) {}

this subclass of sets field b new b. in java, write follows:

class c extends {   c() {     super(new b())   } }

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