How do i assign value to a variable with a result of block of codes containing multiple if's in java8 using lamda expression

Question

I am moving from scala to java8 and looking for examples on how to assign value to a variable by computing block of code with multiple if's.

Given Scala code for reference.

Below works in Scala

object HelloWorld {
    def main(args: Array[String]) = {
        val x = if(condition1) {
                    ....
                    ....
                    ....
                    if(condition2){
                     ....
                     ....
                      "something1"
                    }else
                      "something2"
                  }
                 else
                   "mydefault"
        println(x)
    }

Is there any style of coding other than below inline function example.

String x = (args.length > 0)? args[0]:"default";

But, how to write the same in Java8 programming style ?

@dima snippet i shared is in scala style. i am looking for equivalent java8 style. Hope this explains!! — Jai, Sep 26 '17 at 17:47
@DmytroMitin the original question was "how to write this in java 8 with lambdas". — Dima, Sep 26 '17 at 18:33

score 1 · Answer 1 · answered Sep 26 '17 at 17:50

Scala is an expression-oriented language, so the if block there has a return value. Java does not have this. The equivalent is either to:

final String x = (args.length > 0) ? args[0] : "default";

or make a function that has the logic hidden inside if it's more complex than a simple check.

final String x = getXFromArgs(args);

I use final here because that's the effect of the scala val, in contrast to var

Dmytro Mitin · Accepted Answer · 2017-09-26T18:03:31.387

1

Actually this is in Java 8 (as well as Java 7 etc.):

public class HelloWorld {
    public static void main(String[] args) {
        final String x = (args.length > 0) ? args[0] : "mydefault";
        System.out.println(x);
    }
}

final String x = (args.length > 0)? args[0]:"default"; is pretty functional since it's expression-oriented, side-effects free and immutable.

If you insist on "functional Java 8" you can do also

public class HelloWorld {
    public static void main(String[] args) {
        final String x = Stream.of(args).findFirst().orElse("mydefault");
        final Consumer<String> cons = System.out::println;
        cons.accept(x);
    }
}

but I guess this would be overkill.

edited Sep 26 '17 at 18:03

answered Sep 26 '17 at 17:52

Dmytro Mitin

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@Dmyto Thanks for the "functional java 8" code.I got the style and i understood its overkill for this simple case. – Jai Sep 27 '17 at 14:08
@Jai You're welcome. The "most functional" would be to [emulate](https://stackoverflow.com/questions/876948/higher-kinded-generics-in-java) [higher-kinded](https://medium.com/@johnmcclean/simulating-higher-kinded-types-in-java-b52a18b72c74) generics and encapsulate side effects (like printing to console) in [monad](https://stackoverflow.com/questions/44965/what-is-a-monad/) [IO](https://stackoverflow.com/questions/19687470/scala-io-monad-whats-the-point). But this would be an overkill squared (at least squared). – Dmytro Mitin Sep 27 '17 at 14:31

How do i assign value to a variable with a result of block of codes containing multiple if's in java8 using lamda expression

2 Answers2