hello how do I call a method taking an interface as a parameter from the main ? The code in the main is an example of what I want to achieve but by calling the method map now
What do I write in my map method and how do I call it in the main ? Thank you
What I want to achieve :
StringTransformation addBlah = (e) -> {
e += "boo";
return e;
};
System.out.println(addBlah.transf("Hello")); // prints Helloboo
public class Main{
public static void main(String[] args) {
String a = hello;
// How do I modify the string a by calling map ?
}
void map(StringTransformation t) {
// What do I write ??
}
}
public interface StringTransformation {
String transf(String s);
}
You cannot call map
inside the static
main
method. You must make map
a static method as well if you want to do that. Also we can't help you with what to put inside your map
function if you don't tell us what it should do.
public static void main(String[] args) {
String string = "Hello";
// you can call `mapBoo` like normal here
string = mapBoo(string);
System.out.println(string);
List<String> strings = Arrays.asList("Hello", "this", "is", "a", "test");
// or you can pass mapBoo into the stream.map method since map fits the method signature
List<String> mappedStrings = strings.stream().map(Main::mapBoo)
.collect(Collectors.toList());
for (String mappedString : mappedStrings)
System.out.println(mappedString);
}
static String mapBoo(String s) {
return s + "boo";
}
You want to modify a String
with a given StringTransformation
so you need to pass both of them to the map
method. Also you can turn addBlah
in a more simple lambda :
public static void main(String[] args) {
StringTransformation addBlah = (e) -> e + "boo";
String str = "Hello";
System.out.println(str); // Hello
str = map(addBlah, str);
System.out.println(str); // Helloboo
}
static String map(StringTransformation t, String argument) {
return t.transf(argument);
}
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