java 8 function supplier consumer

1@Testpublic void supplierWithOptional(){    
2  Supplier<Double> doubleSupplier = () -> Math.random();   
3  Optional<Double> optionalDouble = Optional.empty();    
4  System.out.println(optionalDouble.orElseGet(doubleSupplier));}

1@Testpublic void whenNamesPresentUseBothConsumer(){    
2  List<String> cities = Arrays.asList("Sydney", "Dhaka", "New York", "London");   
3  Consumer<List<String>> upperCaseConsumer = list -> {        
4    for(int i=0; i< list.size(); i++){            
5      list.set(i, list.get(i).toUpperCase());        
6    }    
7  };    
8  Consumer<List<String>> printConsumer = list -> list.stream().forEach(System.out::println);    
9  upperCaseConsumer.andThen(printConsumer).accept(cities);}

1@Testpublic void whenNamesPresentUseBothConsumer(){    
2  List<String> cities = Arrays.asList("Sydney", "Dhaka", "New York", "London");    
3  Consumer<List<String>> upperCaseConsumer = list -> {
4    for(int i=0; i< list.size(); i++){            
5      list.set(i, list.get(i).toUpperCase());        
6    }    
7  };    
8  Consumer<List<String>> printConsumer = list -> list.stream().forEach(System.out::println);    
9  upperCaseConsumer.andThen(printConsumer).accept(cities);}