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#1638 Add Parameter Object pattern (#1650)

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* #1638 Add Parameter Object pattern

* #1638 Fix comments and formatting for Parameter Object pattern

* #1638 Fix formatting, commenting, remove string concatenation in Parameter Object pattern

* #1638 Fix readme formatting and log parameter object
This commit is contained in:
Martel Richard
2021-02-28 15:12:48 +05:30
committed by GitHub
parent 03bc4a6b9a
commit 846d05672a
12 changed files with 693 additions and 0 deletions
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62
parameter-object/src/main/java/com/iluwatar/parameter/object/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.parameter.object;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* The syntax of Java language doesn’t allow you to declare a method with a predefined value
* for a parameter. Probably the best option to achieve default method parameters in Java is
* by using the method overloading. Method overloading allows you to declare several methods
* with the same name but with a different number of parameters. But the main problem with
* method overloading as a solution for default parameter values reveals itself when a method
* accepts multiple parameters. Creating an overloaded method for each possible combination of
* parameters might be cumbersome. To deal with this issue, the Parameter Object pattern is used.
* The Parameter Object is simply a wrapper object for all parameters of a method.
* It is nothing more than just a regular POJO. The advantage of the Parameter Object over a
* regular method parameter list is the fact that class fields can have default values.
* Once the wrapper class is created for the method parameter list, a corresponding builder class
* is also created. Usually it's an inner static class. The final step is to use the builder
* to construct a new parameter object. For those parameters that are skipped,
* their default values are going to be used.
*/
public class App {
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
/**
* Program entry point.
*
* @param args command line args
*/
public static void main(String[] args) {
ParameterObject params = ParameterObject.newBuilder()
.withType("sneakers")
.sortBy("brand")
.build();
LOGGER.info(params.toString());
LOGGER.info(new SearchService().search(params));
}
}

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parameter-object/src/main/java/com/iluwatar/parameter/object/ParameterObject.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.parameter.object;
public class ParameterObject {
/**
* Default values are defined here.
*/
public static final String DEFAULT_SORT_BY = "price";
public static final SortOrder DEFAULT_SORT_ORDER = SortOrder.ASC;
private String type;
/**
* Default values are assigned here.
*/
private String sortBy = DEFAULT_SORT_BY;
private SortOrder sortOrder = DEFAULT_SORT_ORDER;
/**
* Overriding default values on object creation only when builder object has a valid value.
*/
private ParameterObject(Builder builder) {
setType(builder.type);
setSortBy(builder.sortBy != null && !builder.sortBy.isBlank() ? builder.sortBy : sortBy);
setSortOrder(builder.sortOrder != null ? builder.sortOrder : sortOrder);
}
public static Builder newBuilder() {
return new Builder();
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getSortBy() {
return sortBy;
}
public void setSortBy(String sortBy) {
this.sortBy = sortBy;
}
public SortOrder getSortOrder() {
return sortOrder;
}
public void setSortOrder(SortOrder sortOrder) {
this.sortOrder = sortOrder;
}
@Override
public String toString() {
return String.format("ParameterObject[type='%s', sortBy='%s', sortOrder='%s']",
type, sortBy, sortOrder);
}
public static final class Builder {
private String type;
private String sortBy;
private SortOrder sortOrder;
private Builder() {
}
public Builder withType(String type) {
this.type = type;
return this;
}
public Builder sortBy(String sortBy) {
this.sortBy = sortBy;
return this;
}
public Builder sortOrder(SortOrder sortOrder) {
this.sortOrder = sortOrder;
return this;
}
public ParameterObject build() {
return new ParameterObject(this);
}
}
}

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parameter-object/src/main/java/com/iluwatar/parameter/object/SearchService.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.parameter.object;
public class SearchService {
/**
* Below two methods of name `search` is overloaded so that we can send a default value for
* one of the criteria and call the final api. A default SortOrder is sent in the first method
* and a default SortBy is sent in the second method. So two separate method definitions are
* needed for having default values for one argument in each case. Hence multiple overloaded
* methods are needed as the number of argument increases.
*/
public String search(String type, String sortBy) {
return getQuerySummary(type, sortBy, SortOrder.ASC);
}
public String search(String type, SortOrder sortOrder) {
return getQuerySummary(type, "price", sortOrder);
}
/**
* The need for multiple method definitions can be avoided by the Parameter Object pattern.
* Below is the example where only one method is required and all the logic for having default
* values are abstracted into the Parameter Object at the time of object creation.
*/
public String search(ParameterObject parameterObject) {
return getQuerySummary(parameterObject.getType(), parameterObject.getSortBy(),
parameterObject.getSortOrder());
}
private String getQuerySummary(String type, String sortBy, SortOrder sortOrder) {
return String.format("Requesting shoes of type \"%s\" sorted by \"%s\" in \"%sending\" order..",
type,
sortBy,
sortOrder.getValue());
}
}

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parameter-object/src/main/java/com/iluwatar/parameter/object/SortOrder.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.parameter.object;
public enum SortOrder {
ASC("asc"),
DESC("desc");
private String value;
SortOrder(String value) {
this.value = value;
}
public String getValue() {
return value;
}
}

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parameter-object/src/test/java/com/iluwatar/parameter/object/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.parameter.object;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Application test
*/
class AppTest {
private static final Logger LOGGER = LoggerFactory.getLogger(AppTest.class);
@Test
void shouldExecuteApplicationWithoutException() {
App.main(new String[]{});
LOGGER.info("Executed successfully without exception.");
}
}

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parameter-object/src/test/java/com/iluwatar/parameter/object/ParameterObjectTest.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.parameter.object;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static org.junit.jupiter.api.Assertions.assertEquals;
class ParameterObjectTest {
private static final Logger LOGGER = LoggerFactory.getLogger(ParameterObjectTest.class);
@Test
public void testForDefaultSortBy() {
//Creating parameter object with default value for SortBy set
ParameterObject params = ParameterObject.newBuilder()
.withType("sneakers")
.sortOrder(SortOrder.DESC)
.build();
assertEquals(ParameterObject.DEFAULT_SORT_BY, params.getSortBy(),
"Default SortBy is not set.");
LOGGER.info("{} Default parameter value is set during object creation as no value is passed."
, "SortBy");
}
@Test
public void testForDefaultSortOrder() {
//Creating parameter object with default value for SortOrder set
ParameterObject params = ParameterObject.newBuilder()
.withType("sneakers")
.sortBy("brand")
.build();
assertEquals(ParameterObject.DEFAULT_SORT_ORDER, params.getSortOrder(),
"Default SortOrder is not set.");
LOGGER.info("{} Default parameter value is set during object creation as no value is passed."
, "SortOrder");
}
}

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parameter-object/src/test/java/com/iluwatar/parameter/object/SearchServiceTest.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.parameter.object;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static org.junit.jupiter.api.Assertions.assertEquals;
class SearchServiceTest {
private static final Logger LOGGER = LoggerFactory.getLogger(SearchServiceTest.class);
private ParameterObject parameterObject;
private SearchService searchService;
@BeforeEach
public void setUp() {
//Creating parameter object with default values set
parameterObject = ParameterObject.newBuilder()
.withType("sneakers")
.build();
searchService = new SearchService();
}
/**
* Testing parameter object against the overloaded method to verify if the behaviour is same.
*/
@Test
public void testDefaultParametersMatch() {
assertEquals(searchService.search(parameterObject), searchService.search("sneakers",
SortOrder.ASC), "Default Parameter values do not not match.");
LOGGER.info("SortBy Default parameter value matches.");
assertEquals(searchService.search(parameterObject), searchService.search("sneakers",
"price"), "Default Parameter values do not not match.");
LOGGER.info("SortOrder Default parameter value matches.");
LOGGER.info("testDefaultParametersMatch executed successfully without errors.");
}
}