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#1313 Add Separated Interface design pattern

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swarajsaaj
2020-09-10 02:57:56 +05:30
parent ef326ee77e
commit f6942cf18d
13 changed files with 527 additions and 0 deletions
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61
separated-interface/src/main/java/com/iluwatar/separatedinterface/App.java Normal file
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/*
* The MIT License
* Copyright © 2014-2019 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.separatedinterface;
import com.iluwatar.separatedinterface.invoice.InvoiceGenerator;
import com.iluwatar.separatedinterface.taxes.DomesticTax;
import com.iluwatar.separatedinterface.taxes.ForeignTax;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* <p>The Strategy pattern (also known as the policy pattern) is a software design pattern that
* enables an algorithm's behavior to be selected at runtime.</p>
*
* <p>Before Java 8 the Strategies needed to be separate classes forcing the developer
* to write lots of boilerplate code. With modern Java it is easy to pass behavior with method
* references and lambdas making the code shorter and more readable.</p>
*
*/
public class App {
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
public static final double PRODUCT_COST = 50.0;
/**
* Program entry point.
*
* @param args command line args
*/
public static void main(String[] args) {
//Create the invoice generator with product cost as 50 and foreign product tax
var internationalProductInvoice = new InvoiceGenerator(PRODUCT_COST, new ForeignTax());
LOGGER.info("Foreign Tax applied: {}", "" + internationalProductInvoice.getAmountWithTax());
//Create the invoice generator with product cost as 50 and domestic product tax
var domesticProductInvoice = new InvoiceGenerator(PRODUCT_COST, new DomesticTax());
LOGGER.info("Domestic Tax applied: {}", "" + domesticProductInvoice.getAmountWithTax());
}
}

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separated-interface/src/main/java/com/iluwatar/separatedinterface/invoice/InvoiceGenerator.java Normal file
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package com.iluwatar.separatedinterface.invoice;
/**
* InvoiceGenerator class generates an invoice, accepting the product cost and calculating the total
* price payable inclusive tax (calculated by {@link TaxCalculator})
*/
public class InvoiceGenerator {
/**
* The TaxCalculator interface to calculate the payable tax.
*/
private final TaxCalculator taxCalculator;
/**
* The base product amount without tax.
*/
private final double amount;
public InvoiceGenerator(double amount, TaxCalculator taxCalculator) {
this.amount = amount;
this.taxCalculator = taxCalculator;
}
public double getAmountWithTax() {
return amount + taxCalculator.calculate(amount);
}
}

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separated-interface/src/main/java/com/iluwatar/separatedinterface/invoice/TaxCalculator.java Normal file
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/*
* The MIT License
* Copyright © 2014-2019 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.separatedinterface.invoice;
public interface TaxCalculator {
double calculate(double amount);
}

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separated-interface/src/main/java/com/iluwatar/separatedinterface/taxes/DomesticTax.java Normal file
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/*
* The MIT License
* Copyright © 2014-2019 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.separatedinterface.taxes;
import com.iluwatar.separatedinterface.invoice.TaxCalculator;
/**
* TaxCalculator for Domestic goods with 20% tax.
*/
public class DomesticTax implements TaxCalculator {
public static final double TAX_PERCENTAGE = 20;
@Override
public double calculate(double amount) {
return amount * TAX_PERCENTAGE / 100.0;
}
}

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separated-interface/src/main/java/com/iluwatar/separatedinterface/taxes/ForeignTax.java Normal file
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/*
* The MIT License
* Copyright © 2014-2019 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.separatedinterface.taxes;
import com.iluwatar.separatedinterface.invoice.TaxCalculator;
/**
* TaxCalculator for foreign goods with 60% tax.
*/
public class ForeignTax implements TaxCalculator {
public static final double TAX_PERCENTAGE = 60;
@Override
public double calculate(double amount) {
return amount * TAX_PERCENTAGE / 100.0;
}
}

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separated-interface/src/test/java/com/iluwatar/separatedinterface/AppTest.java Normal file
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/*
* The MIT License
* Copyright © 2014-2019 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.iluwatar.separatedinterface;
import org.junit.jupiter.api.Test;
import com.iluwatar.separatedinterface.App;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
/**
* Application test.
*/
class AppTest {
@Test
void shouldExecuteWithoutException() {
assertDoesNotThrow(() -> App.main(new String[]{}));
}
}

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separated-interface/src/test/java/com/iluwatar/separatedinterface/invoice/InvoiceGeneratorTest.java Normal file
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package com.iluwatar.separatedinterface.invoice;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import static org.mockito.Mockito.*;
public class InvoiceGeneratorTest {
private InvoiceGenerator target;
@Test
public void testGenerateTax() {
var productCost = 50.0;
var tax = 10.0;
TaxCalculator taxCalculatorMock = mock(TaxCalculator.class);
doReturn(tax).when(taxCalculatorMock).calculate(productCost);
target = new InvoiceGenerator(productCost, taxCalculatorMock);
Assertions.assertEquals(target.getAmountWithTax(), productCost + tax);
verify(taxCalculatorMock, times(1)).calculate(productCost);
}
}

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separated-interface/src/test/java/com/iluwatar/separatedinterface/taxes/DomesticTaxTest.java Normal file
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package com.iluwatar.separatedinterface.taxes;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
public class DomesticTaxTest {
private DomesticTax target;
@Test
public void testTaxCaluclation(){
target = new DomesticTax();
var tax=target.calculate(100.0);
Assertions.assertEquals(tax,20.0);
}
}

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separated-interface/src/test/java/com/iluwatar/separatedinterface/taxes/ForeignTaxTest.java Normal file
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package com.iluwatar.separatedinterface.taxes;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
public class ForeignTaxTest {
private ForeignTax target;
@Test
public void testTaxCaluclation(){
target = new ForeignTax();
var tax=target.calculate(100.0);
Assertions.assertEquals(tax,60.0);
}
}