|
| 1 | +package com.inbravo.jdk7; |
| 2 | + |
| 3 | +import java.util.ArrayList; |
| 4 | +import java.util.List; |
| 5 | + |
| 6 | +/** |
| 7 | + * This class demonstrates the purpose of '@SafeVarargs' |
| 8 | + * |
| 9 | + * @author amit.dixit |
| 10 | + */ |
| 11 | +public final class SafeVarargsAnnotationTest { |
| 12 | + |
| 13 | + public static void main(final String... args) { |
| 14 | + |
| 15 | + /* A list of integers */ |
| 16 | + final List<Integer> listOfIntegers = new ArrayList<>(); |
| 17 | + listOfIntegers.add(1); |
| 18 | + listOfIntegers.add(2); |
| 19 | + listOfIntegers.add(3); |
| 20 | + listOfIntegers.add(4); |
| 21 | + |
| 22 | + /* A list of floats */ |
| 23 | + final List<Float> listOfFloats = new ArrayList<>(); |
| 24 | + listOfFloats.add(3.0f); |
| 25 | + listOfFloats.add(1.0f); |
| 26 | + listOfFloats.add(2.0f); |
| 27 | + listOfFloats.add(3.2f); |
| 28 | + |
| 29 | + /* Scenario 1 - prior to Java 7, usage of code without '@SafeVarargs' */ |
| 30 | + withoutSafeVarargsAnnotation(listOfIntegers, listOfFloats); |
| 31 | + |
| 32 | + /* Scenario 2 - post Java 7, usage of code with '@SafeVarargs' */ |
| 33 | + withSafeVarargsAnnotation(listOfIntegers, listOfFloats); |
| 34 | + } |
| 35 | + |
| 36 | + /** |
| 37 | + * Method without '@SafeVarargs' |
| 38 | + */ |
| 39 | + @SuppressWarnings("unchecked") |
| 40 | + private static void withoutSafeVarargsAnnotation(final List<Integer> listOfIntegers, final List<Float> listOfFloats) { |
| 41 | + |
| 42 | + /* Calling method without '@SafeVarargs' : It generates a warning */ |
| 43 | + displayWithoutSafeVarargs(listOfIntegers, listOfFloats); |
| 44 | + } |
| 45 | + |
| 46 | + /** |
| 47 | + * Method without '@SafeVarargs' |
| 48 | + * |
| 49 | + * Will show a warning to add '@SafeVarargs' |
| 50 | + */ |
| 51 | + private static void withSafeVarargsAnnotation(final List<Integer> listOfIntegers, final List<Float> listOfFloats) { |
| 52 | + |
| 53 | + displayWithSafeVarargs(listOfIntegers, listOfFloats); |
| 54 | + } |
| 55 | + |
| 56 | + /* Without '@SafeVarargs' shows warning */ |
| 57 | + /* Warning 'Type safety: Potential heap pollution via 'varargs' parameter lists' */ |
| 58 | + @SuppressWarnings("unchecked") |
| 59 | + private static <T> void displayWithoutSafeVarargs(final T... lists) { |
| 60 | + |
| 61 | + /* Iterate on list */ |
| 62 | + for (T element : lists) { |
| 63 | + |
| 64 | + System.out.println("Display of elements without @SafeVarargs Annotation"); |
| 65 | + System.out.println(element.getClass().getName() + ": " + element); |
| 66 | + } |
| 67 | + } |
| 68 | + |
| 69 | + /* With usage of @SafeVarargs the Type Safety warning has been suppressed */ |
| 70 | + @SafeVarargs |
| 71 | + private static <T> void displayWithSafeVarargs(final T... lists) { |
| 72 | + |
| 73 | + /* Iterate on list */ |
| 74 | + for (T element : lists) { |
| 75 | + |
| 76 | + System.out.println("Display of elements with @SafeVarargs Annotation"); |
| 77 | + System.out.println(element.getClass().getName() + ": " + element); |
| 78 | + } |
| 79 | + } |
| 80 | +} |
0 commit comments