Answers for "what is void in java"

java doreturn void

doNothing().when(yourMock).yourMockedMethod();

void method java

int a = 20;
int b = 20;
public static void sum(){ // Void Method
  System.out.println(a + b);
}
public static int sum(){ // Return Function
  return a + b;
}

what is void in java

Difference between void and return method
Void Method:
The "void" return type means that this
method doesn't have a return type.
It is mostly used for printing result 
to console