Question

How to convert the below JavaScript example to corresponding code in Java 8 with lambda. I am trying to get the Java 8 lambda.
Made up example.

// js
var isFlag = true,
    name = (function () {
        if (isFlag) return "A";
        else return "B";
    })();
console.log(name);

//outputs: A

I have tried writing it in Java 8, but the syntax or something is wrong. See the below code.

// LambdaTest.java
class LambdaTest {
    public LambdaTest() {
        boolean isFlag = true;
        String name = () -> { //I know this is wrong. It is not an IIFE. But how to write one?
            if (isFlag) return "A";
            else return "B";
        };
        System.out.println(name);
    }
    public static void main(String... args) {
        LambdaTest lt = new LambdaTest();
    }
}

// outputs:
// LambdaTest.java:4: error: incompatible types: String is not a functional interface
//        String name = () -> {
//                      ^
// 1 error

Thanks.

Answer 1

I am not java programmer but seems that something like this do the trick:

import java.util.concurrent.Callable;
import java.lang.String;

class LambdaTest {
    public LambdaTest() {
        boolean isFlag = true;
        Callable<String> name = () -> {
            if (isFlag) return "A";
            else return "B";
        };  
        try {
            System.out.println(name.call());
        } catch (Exception e) {
            //cause call can throw exception so we need to handle that
        }   
    }   
    public static void main(String... args) {
        LambdaTest lt = new LambdaTest();
    }   
}