Java 8 lambda predicate chaining?

Question

I can\'t get it to compile, is it even possible to chain predicate lambdas?

Arrays.asList(\"1\",\"2\",\"3\").stream().filter( (e -> e==\"1\" ).or(e-> e         


        

Answer 1

I was working on a similar problem of predicate chaining and came up with the following

public static  Predicate chain (Function> mapFn, T[]args) {
    return Arrays.asList(args)
        .stream()
        .map(x->mapFn.apply(x))
        .reduce(p->false, Predicate::or);
}

The first parameter to chain is a lambda (Function) that returns a lambda (Predicate) so it needs a couple of arrows

public static void yourExample() {
    String[] filterVals = { "1", "2" };

    Arrays.asList("1","2","3")
        .stream()
        .filter(chain(x-> (y-> y.equals(x)), filterVals))
        .count();
}

For comparison, here is what I was trying to achieve...

public static void myExample() {
    String[] suffixes = { ".png", ".bmp" };
    Predicate p = chain (x-> y-> y.endsWith(x), suffixes);
    File[] graphics = new File("D:/TEMP").listFiles((dir,name)->p.test(name));
    Arrays.asList(graphics).forEach(System.out::println);
}