Sybex:Java 8 OCA/OCP Practice Tests Chapter 23 question 58 typo page 559

[Vlad Alin]

Sybex: Java 8 OCA/OCP Practice Tests Chapter 23(OCP Practice Exam) question 58 typo in explanation page 414 explanation at page 559

58. C. The filter() method passes two of the three elements of the stream through to the terminal operation.
This is "redundant" since the terminal operation checks the same Predicate.

TYPO: It is NOT redundant because omitting "filter(pred)" gives false at allMatch.

import java.util.function.*;
import java.util.stream.*;


class HideAndSeek {
    public static void main(String[] args) {
        Stream<Boolean> hide = Stream.of(true, false, true);
        Predicate<Boolean> pred = b -> b;
        boolean found = hide.filter(pred).allMatch(pred);
        System.out.println(found);
        //true
    }
}

import java.util.function.*;
import java.util.stream.*;


class HideAndSeek {
    public static void main(String[] args) {
        Stream<Boolean> hide = Stream.of(true, false, true);
        Predicate<Boolean> pred = b -> b;
        boolean found = hide.allMatch(pred);
        System.out.println(found);
        //false
    }
}

by alinvlad05

[Paul Clapham]

Vlad Alin wrote:58. C. The filter() method passes two of the three elements of the stream through to the terminal operation.
This is "redundant" since the terminal operation checks the same Predicate.

Indeed, as that example shows: It's true that the two methods check the same Predicate, but they apply it to different elements of the Stream.

[Jeanne Boyarsky]

Have two cows. This error was in all three of our practice exam books (Java 8, 11, and 17) and you were the first to notice. You are absolutely right!

I recorded it in all three errata pages crediting you.