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

/**
 * 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.mockito.Mockito.doThrow;
import static org.mockito.Mockito.mock;

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 = null;
    try {
      connection = openConnection();
      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() throws SQLException {
    Connection mockedConnection = mock(Connection.class);
    doThrow(SQLException.class).when(mockedConnection).close();
    return mockedConnection;
  }
}