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Refactor Discounter examples

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This commit is contained in:
pivovarit 2017-02-06 08:07:05 +01:00
parent daf7af813c
commit 77f1a97e8f
4 changed files with 41 additions and 12 deletions
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3
core-java/src/main/java/com/baeldung/strategy/ChristmasDiscounter.java
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@ -3,8 +3,9 @@ package com.baeldung.strategy;
import java.math.BigDecimal; import java.math.BigDecimal;
public class ChristmasDiscounter implements Discounter { public class ChristmasDiscounter implements Discounter {
@Override @Override
public BigDecimal applyDiscount(final BigDecimal amount) { public BigDecimal apply(BigDecimal amount) {
return amount.multiply(BigDecimal.valueOf(0.9)); return amount.multiply(BigDecimal.valueOf(0.9));
} }
} }

16
core-java/src/main/java/com/baeldung/strategy/Discounter.java
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@ -1,7 +1,19 @@
package com.baeldung.strategy; package com.baeldung.strategy;
import java.math.BigDecimal; import java.math.BigDecimal;
import java.util.function.UnaryOperator;
public interface Discounter { public interface Discounter extends UnaryOperator<BigDecimal> {
BigDecimal applyDiscount(BigDecimal amount);
static Discounter christmas() {
return (amount) -> amount.multiply(BigDecimal.valueOf(0.9));
}
static Discounter newYear() {
return (amount) -> amount.multiply(BigDecimal.valueOf(0.8));
}
static Discounter easter() {
return (amount) -> amount.multiply(BigDecimal.valueOf(0.5));
}
} }

3
core-java/src/main/java/com/baeldung/strategy/EasterDiscounter.java
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@ -3,8 +3,9 @@ package com.baeldung.strategy;
import java.math.BigDecimal; import java.math.BigDecimal;
public class EasterDiscounter implements Discounter { public class EasterDiscounter implements Discounter {
@Override @Override
public BigDecimal applyDiscount(final BigDecimal amount) { public BigDecimal apply(BigDecimal amount) {
return amount.multiply(BigDecimal.valueOf(0.5)); return amount.multiply(BigDecimal.valueOf(0.5));
} }
} }

31
core-java/src/test/java/com/baeldung/strategy/StrategyDesignPatternUnitTest.java
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@ -3,10 +3,12 @@ package com.baeldung.strategy;
import org.junit.Test; import org.junit.Test;
import java.math.BigDecimal; import java.math.BigDecimal;
import java.util.Arrays;
import java.util.List; import java.util.List;
import java.util.function.Function;
import static com.baeldung.strategy.Discounter.*;
import static org.assertj.core.api.Assertions.assertThat; import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.util.Lists.newArrayList;
public class StrategyDesignPatternUnitTest { public class StrategyDesignPatternUnitTest {
@Test @Test
@ -14,7 +16,7 @@ public class StrategyDesignPatternUnitTest {
Discounter staffDiscounter = new EasterDiscounter(); Discounter staffDiscounter = new EasterDiscounter();
final BigDecimal discountedValue = staffDiscounter final BigDecimal discountedValue = staffDiscounter
.applyDiscount(BigDecimal.valueOf(100)); .apply(BigDecimal.valueOf(100));
assertThat(discountedValue) assertThat(discountedValue)
.isEqualByComparingTo(BigDecimal.valueOf(50)); .isEqualByComparingTo(BigDecimal.valueOf(50));
@ -24,13 +26,13 @@ public class StrategyDesignPatternUnitTest {
public void shouldDivideByTwo_WhenApplyingStaffDiscounterWithAnonyousTypes() { public void shouldDivideByTwo_WhenApplyingStaffDiscounterWithAnonyousTypes() {
Discounter staffDiscounter = new Discounter() { Discounter staffDiscounter = new Discounter() {
@Override @Override
public BigDecimal applyDiscount(final BigDecimal amount) { public BigDecimal apply( BigDecimal amount) {
return amount.multiply(BigDecimal.valueOf(0.5)); return amount.multiply(BigDecimal.valueOf(0.5));
} }
}; };
final BigDecimal discountedValue = staffDiscounter final BigDecimal discountedValue = staffDiscounter
.applyDiscount(BigDecimal.valueOf(100)); .apply(BigDecimal.valueOf(100));
assertThat(discountedValue) assertThat(discountedValue)
.isEqualByComparingTo(BigDecimal.valueOf(50)); .isEqualByComparingTo(BigDecimal.valueOf(50));
@ -41,18 +43,31 @@ public class StrategyDesignPatternUnitTest {
Discounter staffDiscounter = amount -> amount.multiply(BigDecimal.valueOf(0.5)); Discounter staffDiscounter = amount -> amount.multiply(BigDecimal.valueOf(0.5));
final BigDecimal discountedValue = staffDiscounter final BigDecimal discountedValue = staffDiscounter
.applyDiscount(BigDecimal.valueOf(100)); .apply(BigDecimal.valueOf(100));
assertThat(discountedValue) assertThat(discountedValue)
.isEqualByComparingTo(BigDecimal.valueOf(50)); .isEqualByComparingTo(BigDecimal.valueOf(50));
} }
@Test @Test
public void shouldApplyListOfDiscounts() { public void shouldApplyAllDiscounts() {
List<Discounter> discounters = newArrayList(); List<Discounter> discounters = Arrays.asList(christmas(), newYear(), easter());
BigDecimal amount = BigDecimal.valueOf(100); BigDecimal amount = BigDecimal.valueOf(100);
discounters.forEach((d) -> d.applyDiscount(amount)); final Discounter combinedDiscounter = discounters
.stream()
.reduce(v -> v, (d1, d2) -> (Discounter) d1.andThen(d2));
combinedDiscounter.apply(amount);
}
@Test
public void shouldChainDiscounters() {
final Function<BigDecimal, BigDecimal> combinedDiscounters = Discounter
.christmas()
.andThen(newYear());
combinedDiscounters.apply(BigDecimal.valueOf(100));
} }
} }