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Work on #385, created project and provided two mute methods

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This commit is contained in:
Narendra Pathai 2016-03-01 17:28:28 +05:30
parent 35d6a54831
commit adb94044ff
6 changed files with 302 additions and 0 deletions
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47
mute-idiom/pom.xml Normal file
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<?xml version="1.0"?>
<!--
The MIT License
Copyright (c) 2014 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.
-->
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.iluwatar</groupId>
<artifactId>java-design-patterns</artifactId>
<version>1.11.0-SNAPSHOT</version>
</parent>
<artifactId>mute-idiom</artifactId>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</project>

77
mute-idiom/src/main/java/com/iluwatar/mute/App.java Normal file
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/**
* The MIT License
* Copyright (c) 2014 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.mute;
import java.io.ByteArrayOutputStream;
import java.sql.Connection;
import java.sql.SQLException;
public class App {
public static void main(String[] args) {
useOfLoggedMute();
useOfMute();
}
/*
* Typically used when the API declares some exception but cannot do so. Usually a signature mistake.
* In this example out is not supposed to throw exception as it is a ByteArrayOutputStream. So we
* utilize mute, which will throw AssertionError if unexpected exception occurs.
*/
private static void useOfMute() {
ByteArrayOutputStream out = new ByteArrayOutputStream();
Mute.mute(() -> out.write("Hello".getBytes()));
}
private static void useOfLoggedMute() {
Connection connection = openConnection();
try {
readStuff(connection);
} catch (SQLException ex) {
ex.printStackTrace();
} finally {
closeConnection(connection);
}
}
/*
* All we can do while failed close of connection is to log it.
*/
private static void closeConnection(Connection connection) {
if (connection != null) {
Mute.loggedMute(() -> connection.close());
}
}
private static void readStuff(Connection connection) throws SQLException {
if (connection != null) {
connection.createStatement();
}
}
private static Connection openConnection() {
return null;
}
}

36
mute-idiom/src/main/java/com/iluwatar/mute/CheckedRunnable.java Normal file
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/**
* The MIT License
* Copyright (c) 2014 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.mute;
/**
* A runnable which may throw exception on execution.
*
*/
@FunctionalInterface
public interface CheckedRunnable {
/**
* Same as {@link Runnable#run()} with a possibility of exception in execution.
* @throws Exception if any exception occurs.
*/
public void run() throws Exception;
}

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mute-idiom/src/main/java/com/iluwatar/mute/Mute.java Normal file
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/**
* The MIT License
* Copyright (c) 2014 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.mute;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
/**
* A utility class that allows you to utilize mute idiom.
*/
public final class Mute {
/**
* Executes the <code>runnable</code> and throws the exception occurred within a {@link AssertionError}.
* This method should be utilized to mute the operations that are guaranteed not to throw an exception.
* For instance {@link ByteArrayOutputStream#write(byte[])} declares in it's signature that it can throw
* an {@link IOException}, but in reality it cannot. This is because the bulk write method is not overridden
* in {@link ByteArrayOutputStream}.
*
* @param runnable a runnable that should never throw an exception on execution.
*/
public static void mute(CheckedRunnable runnable) {
try {
runnable.run();
} catch (Exception e) {
throw new AssertionError(e);
}
}
/**
* Executes the <code>runnable</code> and logs the exception occurred on {@link System#err}.
* This method should be utilized to mute the operations about which most you can do is log.
* For instance while closing a connection to database, all you can do is log the exception
* occurred.
*
* @param runnable a runnable that may throw an exception on execution.
*/
public static void loggedMute(CheckedRunnable runnable) {
try {
runnable.run();
} catch (Exception e) {
e.printStackTrace();
}
}
}

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mute-idiom/src/test/java/com/iluwatar/mute/AppTest.java Normal file
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package com.iluwatar.mute;
import org.junit.Test;
/**
* Tests that Mute idiom example runs without errors.
*
*/
public class AppTest {
@Test
public void test() {
App.main(null);
}
}

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mute-idiom/src/test/java/com/iluwatar/mute/MuteTest.java Normal file
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/**
* The MIT License
* Copyright (c) 2014 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.mute;
import static org.junit.Assert.assertTrue;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;
public class MuteTest {
private static final String MESSAGE = "should not occur";
@Rule public ExpectedException exception = ExpectedException.none();
@Test
public void muteShouldRethrowUnexpectedExceptionAsAssertionError() throws Exception {
exception.expect(AssertionError.class);
exception.expectMessage(MESSAGE);
Mute.mute(() -> methodThrowingException());
}
private void methodThrowingException() throws Exception {
throw new Exception(MESSAGE);
}
@Test
public void loggedMuteShouldLogExceptionTraceBeforeSwallowingIt() throws IOException {
ByteArrayOutputStream stream = new ByteArrayOutputStream();
System.setErr(new PrintStream(stream));
Mute.loggedMute(() -> methodThrowingException());
assertTrue(new String(stream.toByteArray()).contains(MESSAGE));
}
}