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

mute-idiom/src/main/java/com/iluwatar/mute/App.java

@@ -0,0 +1,77 @@
+/**
+ * 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;
+  }
+}

mute-idiom/src/main/java/com/iluwatar/mute/CheckedRunnable.java

@@ -0,0 +1,36 @@
+/**
+ * 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;
+}

mute-idiom/src/main/java/com/iluwatar/mute/Mute.java

@@ -0,0 +1,65 @@
+/**
+ * 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();
+    }
+  }
+}

mute-idiom/src/test/java/com/iluwatar/mute/AppTest.java

@@ -0,0 +1,15 @@
+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);
+  }
+}

mute-idiom/src/test/java/com/iluwatar/mute/MuteTest.java

@@ -0,0 +1,62 @@
+/**
+ * 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));
+  }
+}