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| 1 | +package com.winterbe.java8.samples.lambda; |
| 2 | + |
| 3 | +/** |
| 4 | + * @author Benjamin Winterberg |
| 5 | + */ |
| 6 | +public class LambdaToInterface { |
| 7 | + |
| 8 | + @FunctionalInterface |
| 9 | + public static interface Converter<F, T> { |
| 10 | + T convert(F from); |
| 11 | + } |
| 12 | + |
| 13 | + static class Something { |
| 14 | + String startsWith(String s) { |
| 15 | + return String.valueOf(s.charAt(0)); |
| 16 | + } |
| 17 | + } |
| 18 | + |
| 19 | + interface PersonFactory<P extends Person> { |
| 20 | + P create(String firstName, String lastName); |
| 21 | + } |
| 22 | + |
| 23 | + public static void main(String[] args) { |
| 24 | + Converter<String, Integer> integerConverter1 = (from) -> Integer.valueOf(from); |
| 25 | + Integer converted1 = integerConverter1.convert("123"); |
| 26 | + System.out.println(converted1); // result: 123 |
| 27 | + |
| 28 | + // method reference |
| 29 | + Converter<String, Integer> integerConverter2 = Integer::valueOf; |
| 30 | + Integer converted2 = integerConverter2.convert("123"); |
| 31 | + System.out.println(converted2); // result: 123 |
| 32 | + |
| 33 | + Something something = new Something(); |
| 34 | + |
| 35 | + Converter<String, String> stringConverter = something::startsWith; |
| 36 | + String converted3 = stringConverter.convert("Java"); |
| 37 | + System.out.println(converted3); // result J |
| 38 | + |
| 39 | + // constructor reference |
| 40 | + PersonFactory<Person> personFactory = Person::new; |
| 41 | + Person person = personFactory.create("Peter", "Parker"); |
| 42 | + System.out.println(person); // return Person [firstName=Peter,lastName=Parker] |
| 43 | + } |
| 44 | +} |
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