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#554: Subclass Sandbox pattern (#998)

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* Fix issue #761: ThreadSafeDoubleCheckLocking.java: Instantiating by Reflection call will be successful if you do that firstly

* Create leader election module

* Create Interface of Instance and MessageManager

* Create implementations with token ring algorithm

* Change package structure.
Create basic message system.

* Implement heartbeat and heartbeat invoking message system

* Implement election message handler

* Add leader message handler

* Add main entry point

* Add comments

* Update README.md

* Fix checkstyle issue

* Add Unit Tests

* Add Unit Tests

* Add bully leader selection

* Change System.out to log print.
Add MIT license in each file.

* Add More java doc comments

* Add unit test

* Add unit tests

* Add subclass-sandbox

* Add Unit Test

* Add Unit Test

* Fix Typo

* Move dependency into parent pom.xml

* Change local valuable reference to be var
This commit is contained in:
Azureyjt
2019-10-16 23:21:06 +08:00
committed by Ilkka Seppälä
parent 27c131c2cb
commit a5646b63c1
10 changed files with 517 additions and 1 deletions
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9
pom.xml
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@@ -60,6 +60,7 @@
<jaxb-api.version>2.3.1</jaxb-api.version>
<jaxb-impl.version>2.3.2</jaxb-impl.version>
<annotation-api.version>1.3.2</annotation-api.version>
<system-rules.version>1.19.0</system-rules.version>
</properties>
<modules>
<module>abstract-factory</module>
@@ -180,8 +181,8 @@
<module>bytecode</module>
<module>leader-election</module>
<module>data-locality</module>
<module>subclass-sandbox</module>
<module>circuit-breaker</module>
</modules>
<repositories>
@@ -317,6 +318,12 @@
<artifactId>javassist</artifactId>
<version>3.25.0-GA</version>
</dependency>
<dependency>
<groupId>com.github.stefanbirkner</groupId>
<artifactId>system-rules</artifactId>
<version>${system-rules.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
</dependencyManagement>

29
subclass-sandbox/README.md Normal file
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@@ -0,0 +1,29 @@
---
layout: pattern
title: Subclass Sandbox
folder: subclass-sandbox
permalink: /patterns/subclass-sandbox/
categories: Other
tags:
- Java
- Difficulty-Beginner
---
## Intent
The subclass sandbox pattern describes a basic idea, while not having a lot of detailed mechanics. You will need the pattern when you have several similar subclasses. If you have to make a tiny change, then change the base class, while all subclasses shouldn't have to be touched. So the base class has to be able to provide all of the operations a derived class needs to perform.
## Applicability
The Subclass Sandbox pattern is a very simple, common pattern lurking in lots of codebases, even outside of games. If you have a non-virtual protected method laying around, you’re probably already using something like this. Subclass Sandbox is a good fit when:
- You have a base class with a number of derived classes.
- The base class is able to provide all of the operations that a derived class may need to perform.
- There is behavioral overlap in the subclasses and you want to make it easier to share code between them.
- You want to minimize coupling between those derived classes and the rest of the program.
## Credits
* [Game Programming Patterns - Subclass Sandbox]([http://gameprogrammingpatterns.com/subclass-sandbox.html](http://gameprogrammingpatterns.com/subclass-sandbox.html))

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subclass-sandbox/pom.xml Normal file
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<?xml version="1.0" encoding="UTF-8"?>
<!--
The MIT License
Copyright ? 2014 Ilkka Sepp?l?
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 xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>java-design-patterns</artifactId>
<groupId>com.iluwatar</groupId>
<version>1.22.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>subclass-sandbox</artifactId>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>
<dependency>
<groupId>com.github.stefanbirkner</groupId>
<artifactId>system-rules</artifactId>
</dependency>
</dependencies>
</project>

53
subclass-sandbox/src/main/java/com/iluwatar/subclasssandbox/App.java Normal file
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@@ -0,0 +1,53 @@
/**
* The MIT License
* Copyright (c) 2014-2016 Ilkka Seppälä
* <p>
* 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:
* <p>
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* <p>
* 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.subclasssandbox;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* The subclass sandbox pattern describes a basic idea, while not having a lot
* of detailed mechanics. You will need the pattern when you have several similar
* subclasses. If you have to make a tiny change, then change the base class,
* while all subclasses shouldn't have to be touched. So the base class has to be
* able to provide all of the operations a derived class needs to perform.
*/
public class App {
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
/**
* Entry point of the main program.
* @param args Program runtime arguments.
*/
public static void main(String[] args) {
LOGGER.info("Use superpower: sky launch");
var skyLaunch = new SkyLaunch();
skyLaunch.activate();
LOGGER.info("Use superpower: ground dive");
var groundDive = new GroundDive();
groundDive.activate();
}
}

44
subclass-sandbox/src/main/java/com/iluwatar/subclasssandbox/GroundDive.java Normal file
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@@ -0,0 +1,44 @@
/**
* The MIT License
* Copyright (c) 2014-2016 Ilkka Seppälä
* <p>
* 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:
* <p>
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* <p>
* 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.subclasssandbox;
import org.slf4j.LoggerFactory;
/**
* GroundDive superpower.
*/
public class GroundDive extends Superpower {
public GroundDive() {
super();
logger = LoggerFactory.getLogger(GroundDive.class);
}
@Override
protected void activate() {
move(0, 0, -20);
playSound("GROUNDDIVE_SOUND", 5);
spawnParticles("GROUNDDIVE_PARTICLE", 20);
}
}

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subclass-sandbox/src/main/java/com/iluwatar/subclasssandbox/SkyLaunch.java Normal file
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@@ -0,0 +1,44 @@
/**
* The MIT License
* Copyright (c) 2014-2016 Ilkka Seppälä
* <p>
* 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:
* <p>
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* <p>
* 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.subclasssandbox;
import org.slf4j.LoggerFactory;
/**
* SkyLaunch superpower.
*/
public class SkyLaunch extends Superpower {
public SkyLaunch() {
super();
logger = LoggerFactory.getLogger(SkyLaunch.class);
}
@Override
protected void activate() {
move(0, 0, 20);
playSound("SKYLAUNCH_SOUND", 1);
spawnParticles("SKYLAUNCH_PARTICLE", 100);
}
}

69
subclass-sandbox/src/main/java/com/iluwatar/subclasssandbox/Superpower.java Normal file
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@@ -0,0 +1,69 @@
/**
* The MIT License
* Copyright (c) 2014-2016 Ilkka Seppälä
* <p>
* 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:
* <p>
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* <p>
* 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.subclasssandbox;
import org.slf4j.Logger;
/**
* Superpower abstract class. In this class the basic operations of all types of
* superpowers are provided as protected methods.
*/
public abstract class Superpower {
protected Logger logger;
/**
* Subclass of superpower should implement this sandbox method by calling the
* methods provided in this super class.
*/
protected abstract void activate();
/**
* Move to (x, y, z).
* @param x X coordinate.
* @param y Y coordinate.
* @param z Z coordinate.
*/
protected void move(double x, double y, double z) {
logger.info("Move to ( " + x + ", " + y + ", " + z + " )");
}
/**
* Play sound effect for the superpower.
* @param soundName Sound name.
* @param volumn Value of volumn.
*/
protected void playSound(String soundName, int volumn) {
logger.info("Play " + soundName + " with volumn " + volumn);
}
/**
* Spawn particles for the superpower.
* @param particleType Particle type.
* @param count Count of particles to be spawned.
*/
protected void spawnParticles(String particleType, int count) {
logger.info("Spawn " + count + " particle with type " + particleType);
}
}

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subclass-sandbox/src/test/java/com/iluwatar/subclasssandbox/AppTest.java Normal file
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@@ -0,0 +1,38 @@
/**
* The MIT License
* Copyright (c) 2014-2016 Ilkka Seppälä
* <p>
* 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:
* <p>
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* <p>
* 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.subclasssandbox;
import org.junit.Test;
/**
* App unit tests.
*/
public class AppTest {
@Test
public void testMain() {
String[] args = {};
App.main(args);
}
}

92
subclass-sandbox/src/test/java/com/iluwatar/subclasssandbox/GroundDiveTest.java Normal file
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@@ -0,0 +1,92 @@
/**
* The MIT License
* Copyright (c) 2014-2016 Ilkka Seppälä
* <p>
* 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:
* <p>
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* <p>
* 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.subclasssandbox;
import org.junit.Assert;
import org.junit.Rule;
import org.junit.Test;
import org.junit.contrib.java.lang.system.SystemOutRule;
/**
* GroundDive unit tests.
*/
public class GroundDiveTest {
@Rule
public SystemOutRule log = new SystemOutRule().enableLog();
@Test
public void testMove() {
log.clearLog();
var groundDive = new GroundDive();
groundDive.move(1.0, 1.0, 1.0);
var outputLog = getLogContent(log.getLog());
var expectedLog = "Move to ( 1.0, 1.0, 1.0 )";
Assert.assertEquals(outputLog, expectedLog);
}
@Test
public void testPlaySound() {
log.clearLog();
var groundDive = new GroundDive();
groundDive.playSound("SOUND_NAME", 1);
var outputLog = getLogContent(log.getLog());
var expectedLog = "Play SOUND_NAME with volumn 1";
Assert.assertEquals(outputLog, expectedLog);
}
@Test
public void testSpawnParticles() {
log.clearLog();
var groundDive = new GroundDive();
groundDive.spawnParticles("PARTICLE_TYPE", 100);
final var outputLog = getLogContent(log.getLog());
final var expectedLog = "Spawn 100 particle with type PARTICLE_TYPE";
Assert.assertEquals(outputLog, expectedLog);
}
@Test
public void testActivate() {
log.clearLog();
var groundDive = new GroundDive();
groundDive.activate();;
String[] logs = log.getLog().split("\n");
final var expectedSize = 3;
final var log1 = logs[0].split("-")[1].trim() + " -" + logs[0].split("-")[2].trim();
final var expectedLog1 = "Move to ( 0.0, 0.0, -20.0 )";
final var log2 = getLogContent(logs[1]);
final var expectedLog2 = "Play GROUNDDIVE_SOUND with volumn 5";
final var log3 = getLogContent(logs[2]);
final var expectedLog3 = "Spawn 20 particle with type GROUNDDIVE_PARTICLE";
Assert.assertEquals(logs.length, expectedSize);
Assert.assertEquals(log1, expectedLog1);
Assert.assertEquals(log2, expectedLog2);
Assert.assertEquals(log3, expectedLog3);
}
private String getLogContent(String log) {
return log.split("-")[1].trim();
}
}

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subclass-sandbox/src/test/java/com/iluwatar/subclasssandbox/SkyLaunchTest.java Normal file
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@@ -0,0 +1,91 @@
/**
* The MIT License
* Copyright (c) 2014-2016 Ilkka Seppälä
* <p>
* 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:
* <p>
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* <p>
* 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.subclasssandbox;
import org.junit.Assert;
import org.junit.Rule;
import org.junit.Test;
import org.junit.contrib.java.lang.system.SystemOutRule;
/**
* SkyLaunch unit tests.
*/
public class SkyLaunchTest {
@Rule
public SystemOutRule log = new SystemOutRule().enableLog();
@Test
public void testMove() {
log.clearLog();
var skyLaunch = new SkyLaunch();
skyLaunch.move(1.0, 1.0, 1.0);
var outputLog = getLogContent(log.getLog());
var expectedLog = "Move to ( 1.0, 1.0, 1.0 )";
Assert.assertEquals(outputLog, expectedLog);
}
@Test
public void testPlaySound() {
log.clearLog();
var skyLaunch = new SkyLaunch();
skyLaunch.playSound("SOUND_NAME", 1);
var outputLog = getLogContent(log.getLog());
var expectedLog = "Play SOUND_NAME with volumn 1";
Assert.assertEquals(outputLog, expectedLog);
}
@Test
public void testSpawnParticles() {
log.clearLog();
var skyLaunch = new SkyLaunch();
skyLaunch.spawnParticles("PARTICLE_TYPE", 100);
var outputLog = getLogContent(log.getLog());
var expectedLog = "Spawn 100 particle with type PARTICLE_TYPE";
Assert.assertEquals(outputLog, expectedLog);
}
@Test
public void testActivate() {
log.clearLog();
var skyLaunch = new SkyLaunch();
skyLaunch.activate();;
String[] logs = log.getLog().split("\n");
final var expectedSize = 3;
final var log1 = getLogContent(logs[0]);
final var expectedLog1 = "Move to ( 0.0, 0.0, 20.0 )";
final var log2 = getLogContent(logs[1]);
final var expectedLog2 = "Play SKYLAUNCH_SOUND with volumn 1";
final var log3 = getLogContent(logs[2]);
final var expectedLog3 = "Spawn 100 particle with type SKYLAUNCH_PARTICLE";
Assert.assertEquals(logs.length, expectedSize);
Assert.assertEquals(log1, expectedLog1);
Assert.assertEquals(log2, expectedLog2);
Assert.assertEquals(log3, expectedLog3);
}
private String getLogContent(String log) {
return log.split("-")[1].trim();
}
}