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eliminate all warnings of checkstyle.

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This commit is contained in:
zafarella 2015-09-24 13:29:39 -04:00
parent 36809537d9
commit 60f9b71278
6 changed files with 121 additions and 124 deletions
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85
singleton/src/main/java/com/iluwatar/singleton/App.java
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@ -1,58 +1,63 @@
/**
* Singleton pattern.
*/
package com.iluwatar.singleton;
/**
*
* Singleton pattern ensures that the class ({@link IvoryTower}) can have only one
* existing instance per Java classloader instance and provides global access to it.
* <p>
* existing instance per Java classloader instance and provides global access to it.
* <p/>
* http://stackoverflow.com/questions/70689/what-is-an-efficient-way-to-implement-a-singleton-pattern-in-java
*<p>
* The risk of this pattern is that bugs resulting from setting a singleton up in a distributed environment can
* be tricky to debug, since it will work fine if you debug with a single classloader. Additionally, these
* problems can crop up a while after the implementation of a singleton, since they may start out synchronous and
* only become async with time, so you it may not be clear why you are seeing certain changes in behaviour.
* <p>
* <p/>
* The risk of this pattern is that bugs resulting from setting a singleton up in
* a distributed environment can be tricky to debug, since it will work fine if you
* debug with a single classloader. Additionally, these problems can crop up a while
* after the implementation of a singleton, since they may start out synchronous and
* only become async with time, so you it may not be clear why you are seeing certain
* changes in behaviour.
* <p/>
* http://stackoverflow.com/questions/17721263/singleton-across-jvm-or-application-instance-or-tomcat-instance
*/
public class App {
/**
* Program entry point
* @param args command line args
*/
public static void main(String[] args) {
/**
* Program entry point.
*
* @param args command line args
*/
public static void main(String[] args) {
// eagerly initialized singleton
IvoryTower ivoryTower1 = IvoryTower.getInstance();
IvoryTower ivoryTower2 = IvoryTower.getInstance();
System.out.println("ivoryTower1=" + ivoryTower1);
System.out.println("ivoryTower2=" + ivoryTower2);
// eagerly initialized singleton
IvoryTower ivoryTower1 = IvoryTower.getInstance();
IvoryTower ivoryTower2 = IvoryTower.getInstance();
System.out.println("ivoryTower1=" + ivoryTower1);
System.out.println("ivoryTower2=" + ivoryTower2);
// lazily initialized singleton
ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower1 = ThreadSafeLazyLoadedIvoryTower
.getInstance();
ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower2 = ThreadSafeLazyLoadedIvoryTower
.getInstance();
System.out.println("threadSafeIvoryTower1=" + threadSafeIvoryTower1);
System.out.println("threadSafeIvoryTower2=" + threadSafeIvoryTower2);
// lazily initialized singleton
ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower1 = ThreadSafeLazyLoadedIvoryTower
.getInstance();
ThreadSafeLazyLoadedIvoryTower threadSafeIvoryTower2 = ThreadSafeLazyLoadedIvoryTower
.getInstance();
System.out.println("threadSafeIvoryTower1=" + threadSafeIvoryTower1);
System.out.println("threadSafeIvoryTower2=" + threadSafeIvoryTower2);
// enum singleton
EnumIvoryTower enumIvoryTower1 = EnumIvoryTower.INSTANCE;
EnumIvoryTower enumIvoryTower2 = EnumIvoryTower.INSTANCE;
System.out.println("enumIvoryTower1=" + enumIvoryTower1);
System.out.println("enumIvoryTower2=" + enumIvoryTower2);
// enum singleton
EnumIvoryTower enumIvoryTower1 = EnumIvoryTower.INSTANCE;
EnumIvoryTower enumIvoryTower2 = EnumIvoryTower.INSTANCE;
System.out.println("enumIvoryTower1=" + enumIvoryTower1);
System.out.println("enumIvoryTower2=" + enumIvoryTower2);
InitializingOnDemandHolderIdiom demandHolderIdiom = InitializingOnDemandHolderIdiom.getInstance();
System.out.println(demandHolderIdiom);
InitializingOnDemandHolderIdiom demandHolderIdiom2 = InitializingOnDemandHolderIdiom.getInstance();
System.out.println(demandHolderIdiom2);
InitializingOnDemandHolderIdiom demandHolderIdiom =
InitializingOnDemandHolderIdiom.getInstance();
System.out.println(demandHolderIdiom);
InitializingOnDemandHolderIdiom demandHolderIdiom2 =
InitializingOnDemandHolderIdiom.getInstance();
System.out.println(demandHolderIdiom2);
ThreadSafeDoubleCheckLocking dcl1 = ThreadSafeDoubleCheckLocking.getInstance();
System.out.println(dcl1);
ThreadSafeDoubleCheckLocking dcl2 = ThreadSafeDoubleCheckLocking.getInstance();
System.out.println(dcl2);
}
ThreadSafeDoubleCheckLocking dcl1 = ThreadSafeDoubleCheckLocking.getInstance();
System.out.println(dcl1);
ThreadSafeDoubleCheckLocking dcl2 = ThreadSafeDoubleCheckLocking.getInstance();
System.out.println(dcl2);
}
}

15
singleton/src/main/java/com/iluwatar/singleton/EnumIvoryTower.java
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@ -1,18 +1,15 @@
/**
* Enum Singleton class.
* Effective Java 2nd Edition (Joshua Bloch) p. 18
*/
package com.iluwatar.singleton;
/**
* Enum based singleton implementation.
* Effective Java 2nd Edition (Joshua Bloch) p. 18
*/
public enum EnumIvoryTower {
INSTANCE;
INSTANCE;
@Override
public String toString() {
return getDeclaringClass().getCanonicalName() + "@" + hashCode();
}
@Override
public String toString() {
return getDeclaringClass().getCanonicalName() + "@" + hashCode();
}
}

28
singleton/src/main/java/com/iluwatar/singleton/InitializingOnDemandHolderIdiom.java
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@ -1,6 +1,3 @@
/**
* Singleton pattern.
*/
package com.iluwatar.singleton;
import java.io.Serializable;
@ -18,21 +15,22 @@ import java.io.Serializable;
*/
public class InitializingOnDemandHolderIdiom implements Serializable {
private static final long serialVersionUID = 1L;
private static final long serialVersionUID = 1L;
private InitializingOnDemandHolderIdiom() {
}
private InitializingOnDemandHolderIdiom() {
}
public static InitializingOnDemandHolderIdiom getInstance() {
return HelperHolder.INSTANCE;
}
public static InitializingOnDemandHolderIdiom getInstance() {
return HelperHolder.INSTANCE;
}
protected Object readResolve() {
return getInstance();
}
protected Object readResolve() {
return getInstance();
}
private static class HelperHolder {
public static final InitializingOnDemandHolderIdiom INSTANCE = new InitializingOnDemandHolderIdiom();
}
private static class HelperHolder {
public static final InitializingOnDemandHolderIdiom INSTANCE =
new InitializingOnDemandHolderIdiom();
}
}

39
singleton/src/main/java/com/iluwatar/singleton/IvoryTower.java
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@ -1,6 +1,3 @@
/**
* Singleton pattern.
*/
package com.iluwatar.singleton;
/**
@ -10,24 +7,24 @@ package com.iluwatar.singleton;
*/
public final class IvoryTower {
/**
* Static to class instance of the class.
*/
private static IvoryTower instance = new IvoryTower();
/**
* Static to class instance of the class.
*/
private static IvoryTower instance = new IvoryTower();
/**
* Private constructor so nobody can instantiate the class.
*/
private IvoryTower() {
}
/**
* Private constructor so nobody can instantiate the class.
*/
private IvoryTower() {
}
/**
* To be called by user to
* obtain instance of the class.
*
* @return instance of the singleton.
*/
public static IvoryTower getInstance() {
return instance;
}
/**
* To be called by user to
* obtain instance of the class.
*
* @return instance of the singleton.
*/
public static IvoryTower getInstance() {
return instance;
}
}

48
singleton/src/main/java/com/iluwatar/singleton/ThreadSafeDoubleCheckLocking.java
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@ -1,7 +1,3 @@
/**
* Singleton pattern.
*
*/
package com.iluwatar.singleton;
/**
@ -15,29 +11,35 @@ package com.iluwatar.singleton;
*/
public class ThreadSafeDoubleCheckLocking {
private static volatile ThreadSafeDoubleCheckLocking INSTANCE;
private static volatile ThreadSafeDoubleCheckLocking INSTANCE;
/**
* private constructor to prevent client from instantiating.
*/
private ThreadSafeDoubleCheckLocking() {
//to prevent instantiating by Reflection call
if (INSTANCE != null)
throw new IllegalStateException("Already initialized.");
/**
* private constructor to prevent client from instantiating.
*/
private ThreadSafeDoubleCheckLocking() {
//to prevent instantiating by Reflection call
if (INSTANCE != null) {
throw new IllegalStateException("Already initialized.");
}
}
public static ThreadSafeDoubleCheckLocking getInstance() {
//local variable increases performance by 25 percent
//Joshua Bloch "Effective Java, Second Edition", p. 283-284
ThreadSafeDoubleCheckLocking result = INSTANCE;
/**
* Public accessor.
*
* @return an instance of the class.
*/
public static ThreadSafeDoubleCheckLocking getInstance() {
//local variable increases performance by 25 percent
//Joshua Bloch "Effective Java, Second Edition", p. 283-284
ThreadSafeDoubleCheckLocking result = INSTANCE;
if (result == null) {
synchronized (ThreadSafeDoubleCheckLocking.class) {
result = INSTANCE;
if (result == null) {
synchronized (ThreadSafeDoubleCheckLocking.class) {
result = INSTANCE;
if (result == null) {
INSTANCE = result = new ThreadSafeDoubleCheckLocking();
}
}
INSTANCE = result = new ThreadSafeDoubleCheckLocking();
}
return result;
}
}
return result;
}
}

30
singleton/src/main/java/com/iluwatar/singleton/ThreadSafeLazyLoadedIvoryTower.java
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@ -1,6 +1,3 @@
/**
* Singleton pattern.
*/
package com.iluwatar.singleton;
/**
@ -10,20 +7,21 @@ package com.iluwatar.singleton;
*/
public class ThreadSafeLazyLoadedIvoryTower {
private static ThreadSafeLazyLoadedIvoryTower instance = null;
private static ThreadSafeLazyLoadedIvoryTower instance = null;
private ThreadSafeLazyLoadedIvoryTower() {
private ThreadSafeLazyLoadedIvoryTower() {
}
/**
* The instance gets created only when it is called for first time.
* Lazy-loading
*/
public synchronized static ThreadSafeLazyLoadedIvoryTower getInstance() {
if (instance == null) {
instance = new ThreadSafeLazyLoadedIvoryTower();
}
public synchronized static ThreadSafeLazyLoadedIvoryTower getInstance() {
/*
* The instance gets created only when it is called for first time.
* Lazy-loading
*/
if (instance == null) {
instance = new ThreadSafeLazyLoadedIvoryTower();
}
return instance;
}
return instance;
}
}