CODEWITHSUNDEEP
java-8
AbhiN
AbhiN

Reputation: 650

Lambda expression quiz

I have defined a functional interface StringFormatter as below

public interface StringFormatter{
    String format(String s1, String s2);
}

How can I write main class which creates lambda expression for above interface and defines format() for below 2 results?

Upvotes: 3

Views: 1075

Answers (4)

Snigdhadeb Chatterjee
Snigdhadeb Chatterjee

Reputation: 31

    StringFormatter formatter = (str1,str2) -> str1 + str2;
    StringFormatter formatter1 = (str1,str2) -> str1 + "-" + str2;

    String formatedString = formatter.format("Hello", "World");
    String formatedString1 = formatter1.format("Hello", "World");

    System.out.println("Formated String (Type 1) : "+formatedString);
    System.out.println("Formated String (Type 2) : "+formatedString1);

Upvotes: 0

Szymon Stepniak
Szymon Stepniak

Reputation: 42174

In this case you can easily initialize two variables holding lambda expressions like:

StringFormatter formatter1 = (s1,s2) -> s1 + s2;
StringFormatter formatter2 = (s1,s2) -> s1 + "-" + s2;

Then you can call formatter1.format(s1,s2) and formatter2.format(s1,s2).

Following example:

public class Test {

    public interface StringFormatter{
        String format(String s1, String s2);
    }

    public static void main(String[] args) {
        final StringFormatter formatter1 = (s1,s2) -> s1 + s2;
        final StringFormatter formatter2 = (s1,s2) -> s1 + "-" + s2;

        System.out.println(formatter1.format("lorem", "ipsum"));
        System.out.println(formatter2.format("lorem", "ipsum"));
    }
}

produces output:

loremipsum
lorem-ipsum

Upvotes: 3

Ousmane D.
Ousmane D.

Reputation: 56393

We can use a Functional interface as a target type like this:

StringFormatter func = (s1, s2) -> s1 + s2;

in which case you can call it like:

String result = func.format("first","second");

you can also put the logic into a method as such:

static String formatter(StringFormatter func, String s1, String s2){
       return func.format(s1, s2);
}

then call it:

String result = formatter((s1, s2) -> s1 + s2, "first", "second");
String anotherResult = formatter((s1, s2) -> s1 +"-"+ s2, "first", "second");

in which case you simply pass the behaviour directly without having to create different inline functions for each scenario.

Upvotes: 3

fps
fps

Reputation: 34450

You might write something like this:

StringFormatter formatter1 = (s1, s2) -> s1 + s2;

StringFormatter formatter2 = (s1, s2) -> s1 + "-" + s2;

Usage:

String result1 = formatter1.format("a", "b"); // ab

String result2 = formatter2.format("a", "b"); // a-b

Upvotes: 2

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